tag:blogger.com,1999:blog-38753994618091367802024-03-19T02:13:29.202-07:00Planets AboveAlex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.comBlogger18125tag:blogger.com,1999:blog-3875399461809136780.post-90553785620149564792013-06-04T20:13:00.000-07:002013-06-04T20:13:12.014-07:00"Movie Posters" for NASA planetary missions<div class="separator" style="clear: both; text-align: left;">
In the next few years, several NASA missions to the outer solar system will be arriving at their destinations: New Horizons flies by Pluto in 2015, and Juno enters orbit around Jupiter in 2016. </div>
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These two spacecraft also have fairly distinctive silhouettes, and I thought I could highlight them and their destinations with some moody backlighting. So I made these two posters:</div>
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<b><i>New Horizons in the Pluto system</i></b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEbcwK7AEEB0UNOMC1J_sYHiA3BA4gYTl4jB8X5a2JZKmAHeQxnAkef-B0lEEfuja7mvOW7WJuwVwFeU1b6GhtJp7PZ6f6Ss2QqmDcym4CWQfcWaRgk2Bz5j5pWBrX5FS8tRBLzLJ6AqM/s1600/NH4.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEbcwK7AEEB0UNOMC1J_sYHiA3BA4gYTl4jB8X5a2JZKmAHeQxnAkef-B0lEEfuja7mvOW7WJuwVwFeU1b6GhtJp7PZ6f6Ss2QqmDcym4CWQfcWaRgk2Bz5j5pWBrX5FS8tRBLzLJ6AqM/s640/NH4.jpg" width="510" /></a></div>
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<b><i>Juno entering the Jupiter system</i></b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWrDVxYeCXXH_gVdWCp51clHjNPMczQHp7eWJ0TFHTeo0DHhX_AuNv8gYqaVWtg9s0yp0nQWiPssVbDMNH-bru62lCdpzXXSL8LbImxnydKVTl9RtODceMqvjF5In1V7le_DfHtQyog74/s1600/jupiter-crescent.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWrDVxYeCXXH_gVdWCp51clHjNPMczQHp7eWJ0TFHTeo0DHhX_AuNv8gYqaVWtg9s0yp0nQWiPssVbDMNH-bru62lCdpzXXSL8LbImxnydKVTl9RtODceMqvjF5In1V7le_DfHtQyog74/s640/jupiter-crescent.jpg" width="550" /></a></div>
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Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com2tag:blogger.com,1999:blog-3875399461809136780.post-27589093890442331482013-05-31T17:45:00.005-07:002013-06-01T17:56:53.758-07:00Our Evolving View of the Cosmic Microwave Background - Revolving!After putting together my <a href="http://planetsabove.blogspot.com/2013/05/spinning-moons.html" target="_blank"><i>Spinning Moons</i> post,</a> I didn't want my cosmologist friends to feel left out - so I constructed some spinning maps of the <a href="http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation" target="_blank">Cosmic Microwave Background</a> (CMB) from different observational eras.<br />
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The earliest comes from the<b> </b><a href="http://en.wikipedia.org/wiki/Cosmic_Background_Explorer" target="_blank"><b>COBE satellite</b>,</a> launched in 1989.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC0uykzVBzNfPqXsNvpTYkdTyLJ-u5S90ICN7W3cB9e8CK-haaFJXInGmDwV4FskxqbVIqfgqh8Cn8cqiq4yl3LMxMthXa9DOCLVnPG-fe9FeXNhJxEtR-UhwtkNWdP-R04EtsIkNEA3A/s1600/cobe2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgC0uykzVBzNfPqXsNvpTYkdTyLJ-u5S90ICN7W3cB9e8CK-haaFJXInGmDwV4FskxqbVIqfgqh8Cn8cqiq4yl3LMxMthXa9DOCLVnPG-fe9FeXNhJxEtR-UhwtkNWdP-R04EtsIkNEA3A/s320/cobe2.gif" width="320" /></a></div>
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Next came the much more detailed results from the<b> <a href="http://en.wikipedia.org/wiki/WMAP" target="_blank">WMAP satellite</a></b>, launched in 2001.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcAYu8SR-OQBaLb0HoSFGcmLtEYWgGKRfZvdgYxHCbByDnKM51KGFKjEpn0nzT-AsYIR4L4z1L2UAXnGMy_rEhdJu50jM97MdmMO2o_3oEfsvhsfVQAzBnhLcPMCPfas-n8fjNdeGQAfw/s1600/wmap2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcAYu8SR-OQBaLb0HoSFGcmLtEYWgGKRfZvdgYxHCbByDnKM51KGFKjEpn0nzT-AsYIR4L4z1L2UAXnGMy_rEhdJu50jM97MdmMO2o_3oEfsvhsfVQAzBnhLcPMCPfas-n8fjNdeGQAfw/s320/wmap2.gif" width="320" /></a></div>
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Our most recent and detailed view comes from <b>ESA's <a href="http://en.wikipedia.org/wiki/Planck_(spacecraft)" target="_blank">Planck satellite</a></b>, launched in 2009.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpyZVbEHPppHA7BkmNJYDtjjVEpg7C_YSgwmsy2SGHynAUlB9sGAROIS0zD6gCaFxLcACgOP21yqv7hguz13dHZcVvI3sz9N90qEr2wbM5OH8XNg6MtZOXabrAov-ARGyCpXJX3xNGjYc/s1600/planck2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpyZVbEHPppHA7BkmNJYDtjjVEpg7C_YSgwmsy2SGHynAUlB9sGAROIS0zD6gCaFxLcACgOP21yqv7hguz13dHZcVvI3sz9N90qEr2wbM5OH8XNg6MtZOXabrAov-ARGyCpXJX3xNGjYc/s320/planck2.gif" width="320" /></a></div>
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<b>Bonus</b>! Here's a view of the K-band (23 GHz) foreground contamination, showing the mess that is our home galaxy as seen by the WMAP satellite.<br />
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<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com18tag:blogger.com,1999:blog-3875399461809136780.post-79894602362408062952013-05-30T16:41:00.001-07:002013-05-30T17:08:12.792-07:00Moons of Minor Planets: Revisiting an old visualization<span style="font-family: inherit;">With the news that the Near-Earth Asteroid <span style="background-color: white; line-height: 19px;">1998 QE2 has a small natural satellite of its own percolating through the 'net, I thought it might be a good time to re-visit one of my first animated visualizations. During my PhD, I studied a sample of very widely-separated binary objects in the Kuiper Belt - these are like distant asteroids with moons of their own, but in many cases the moon (the 'secondary') is nearly as large is the main object (the 'primary'). </span></span><span style="font-family: inherit;"><span style="background-color: white; line-height: 19px;">One of the objects I was studying was </span><b style="line-height: 18.99305534362793px;">2006 CH69</b><span style="background-color: white; line-height: 19px;">, which at the time had a temporary designation of <b>L5c02</b>. After a series of very careful observations, I measured the orbit of the secondary of </span><b style="line-height: 18.99305534362793px;">2006 CH69</b><span style="line-height: 18.99305534362793px;"> around the primary. It turned out that the system was remarkably eccentric, with <b>e=0.90</b></span><span style="background-color: white; color: #444444; line-height: 16px;"><b>±0.02 </b></span><span style="line-height: 18.99305534362793px;">- making it the most eccentric binary minor planet with a well-measured orbit. Given the other properties of the orbit, this meant that when they were at their closest, the two bodies in the system were only separated by about 2,800 kilometers, while at the other extreme of their orbit about each other they were separated by over 52,000 kilometers. This huge swing between the two extremes takes place over half an orbital period, or </span><span style="line-height: 18.99305534362793px;">roughly 2 years.</span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 18.99305534362793px;">When I discovered this, I wondered what it would be like to stand on the surface of the primary of </span><b style="line-height: 18.99305534362793px;">2006 CH69</b><span style="line-height: 18.99305534362793px;"> and look up at the secondary over the course of their mutual orbit. Using a rough calculation of the size of the secondary body, I determined its apparent size as seen from the surface of the primary, and compared it to the apparent size of the full moon (our 'secondary') as seen from the surface of the Earth (our 'primary').</span></span><br />
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<span style="line-height: 18.99305534362793px;">At the time, I was just learning the ropes of how to make effective visualizations, but I put the following animation together:</span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 18.99305534362793px;">On the right you see the apparent size of the secondary - here referred to with its earlier designation of </span><b style="line-height: 18.99305534362793px;">L5c02b</b><span style="line-height: 18.99305534362793px;"> - as seen from the surface of the system primary. The animation starts with the system at their most widely separated, with the secondary appearing roughly 1/5th the size of the full moon. At their closest half an orbit later, </span><b style="line-height: 18.99305534362793px;">L5c02b</b><span style="line-height: 18.99305534362793px;"> grows to appear over 3 times the size of the full moon on the sky!</span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 18.99305534362793px;">I took some liberties with this animation - we don't know what the rotation period of </span><b style="line-height: 18.99305534362793px;">L5c02b</b><span style="line-height: 18.99305534362793px;"> is, nor do we know if it has any surface markings, or even if it has a round shape! Future, more detailed studies will be needed to refine our understanding of the system.</span></span><br />
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<span style="line-height: 18.99305534362793px;">I later made an animation showing the motion of six of the systems I studied, as seen from the Earth, and the observations we collected of them over the <i>course of</i></span><i><span style="line-height: 18.99305534362793px;"> a decade</span><span style="line-height: 18.99305534362793px;">.</span></i></span><br />
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<a href="http://vimeo.com/27880676">Mutual Orbits of Ultra-Wide Trans-Neptunian Binaries</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.</div>
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<span style="font-family: inherit; line-height: 18.99305534362793px;">Click through to read the details of the animation. You can also learn more about these systems in an article I wrote for the Gemini Observatory Newsletter <a href="http://www.gemini.edu/images/pio/newsletters/pdf/gf_1211.pdf" target="_blank">[pdf, page 23]</a>.</span>Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com3tag:blogger.com,1999:blog-3875399461809136780.post-17981876255266187462013-05-22T23:10:00.001-07:002013-05-24T00:42:32.510-07:00Spinning MoonsThis afternoon I was learning a few of the bells and whistles of the <a href="http://matplotlib.org/basemap/" target="_blank">matplotlib Basemap toolkit</a>. As a side product, I ended up with a script to animate a wobbling/spinning planet.<br />
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So, here's a couple moons!<br />
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Titan, largest moon of Saturn:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZPoYtk4V8BC8Toy7eOawZbwzl-7EEXjHBJFFmhfEjthb7h0ON-F-XerOjlWerj62Ta6ZTjmk0Fm_1CtCUbcw4jsiU71vFyG7asPC5X2kwWHUN_rNDSU5OpNgJlVjB7t3koJFjeIC-Y8s/s1600/anim5.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZPoYtk4V8BC8Toy7eOawZbwzl-7EEXjHBJFFmhfEjthb7h0ON-F-XerOjlWerj62Ta6ZTjmk0Fm_1CtCUbcw4jsiU71vFyG7asPC5X2kwWHUN_rNDSU5OpNgJlVjB7t3koJFjeIC-Y8s/s320/anim5.gif" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhl1BqaL-Mlsqzj-I5nQXYckQIo1209-dR9TF3M0wUUyfeT69y-8SkBX1qCq2ozBclXXlC9OUy39f3H7pTUc3DzeistRqSr2nUIU4u9HrNlYEuDxlKn5kcXasHmg4HEg4MZe-oqNUSPWQ/s1600/titan1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhl1BqaL-Mlsqzj-I5nQXYckQIo1209-dR9TF3M0wUUyfeT69y-8SkBX1qCq2ozBclXXlC9OUy39f3H7pTUc3DzeistRqSr2nUIU4u9HrNlYEuDxlKn5kcXasHmg4HEg4MZe-oqNUSPWQ/s320/titan1.gif" width="320" /></a></div>
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Source for <a href="http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4813" target="_blank">map one</a> and <a href="http://laps.noaa.gov/albers/sos/features/combined_titan_lon_zero_center.png" target="_blank">map two</a>.<br />
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Io, innermost of Jupiter's large moons and most volcanically active body in the solar system:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhw-klxOjfAjLdlarkpqdnkIXvqg-Lh-Ty1L3QsBxvuTfuP_L9wWOP8zWG7fGyuBpvpGiiAfyWwy6eozRWe0Gy8Sop7o2i69DPEN9JY_2Uwh8-JfFFJddmr22XrYMEgcvkaKVOqcRMerFE/s1600/io1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhw-klxOjfAjLdlarkpqdnkIXvqg-Lh-Ty1L3QsBxvuTfuP_L9wWOP8zWG7fGyuBpvpGiiAfyWwy6eozRWe0Gy8Sop7o2i69DPEN9JY_2Uwh8-JfFFJddmr22XrYMEgcvkaKVOqcRMerFE/s320/io1.gif" width="320" /></a></div>
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<a href="http://laps.noaa.gov/albers/sos/sos.html" target="_blank">Map source</a>.<br />
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Europa, next of Jupiter's large moons, with a skin of ice covering a sub-surface ocean:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXzy_8p7vaEdaoAAxch5kIcFU2EUk6zNzjsQJ_C3nozrh4e0s_4rwqrqMRTSKB28fbD2witrE2eeCU8fUORadeYKHPjkKCLTu-tpQsZkYclI9aJHN4ZaOdlFMeXrakkYKiBTSM2GsmdDQ/s1600/europa2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXzy_8p7vaEdaoAAxch5kIcFU2EUk6zNzjsQJ_C3nozrh4e0s_4rwqrqMRTSKB28fbD2witrE2eeCU8fUORadeYKHPjkKCLTu-tpQsZkYclI9aJHN4ZaOdlFMeXrakkYKiBTSM2GsmdDQ/s320/europa2.gif" width="320" /></a></div>
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<a href="http://www.johnstonsarchive.net/spaceart/cylmaps.html" target="_blank">Map source</a>.</div>
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Ganymede, third large moon of Jupiter, and largest moon in the solar system:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7BNNWyzPXjCk1UPToPLH3jUlwkFdY5jYGL56a2fqN1onvgmIB8fVrCGFHE9rS0CUkH73EoMRYHY9TisF6g38cVZuipZck9MwuzZ4eIyYvUvsy_Spn_4OatMy_vuk8GE8ksNYJFl1NsjY/s1600/ganymede3.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7BNNWyzPXjCk1UPToPLH3jUlwkFdY5jYGL56a2fqN1onvgmIB8fVrCGFHE9rS0CUkH73EoMRYHY9TisF6g38cVZuipZck9MwuzZ4eIyYvUvsy_Spn_4OatMy_vuk8GE8ksNYJFl1NsjY/s320/ganymede3.gif" width="320" /></a></div>
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<a href="http://www.mmedia.is/~bjj/data/ganymede/" target="_blank">Map source</a>.</div>
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Callisto, Jupiter's most distant large moon, with one of the most cratered surfaces in the solar system:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzsqULhsd6xSN4-tIbsY9awhkMn__KIWGIfrcGwhKt9WltN86XVH538qUHGE3LmhJf78RzpiDXcoaHpgocEI5jhcX5b3f5nb-6eNuQhLWzeSecaRnORwBzuBP0vGnPQi0Zcixn9cGLH7s/s1600/callisto1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzsqULhsd6xSN4-tIbsY9awhkMn__KIWGIfrcGwhKt9WltN86XVH538qUHGE3LmhJf78RzpiDXcoaHpgocEI5jhcX5b3f5nb-6eNuQhLWzeSecaRnORwBzuBP0vGnPQi0Zcixn9cGLH7s/s320/callisto1.gif" width="320" /></a></div>
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<a href="http://www.mmedia.is/~bjj/data/callisto/" target="_blank">Map source</a>.<br />
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Enjoy! If you have other moons you would like to see added, let me know and I'll see what I can do!<br />
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<a href="http://www.blogger.com/blogger.g?blogID=3875399461809136780" name="update"></a><i>Update:</i> At your request, I'll be adding some additional moons below.<br />
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<i>The</i> Moon!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhidpTzDwnrDmkx0IlsEH8UBZSI1GDtrE1BjTQz1rxlPrchB6NSLwX4tMuNzGqgLmlFBIiLXV5V4DZh9OpOcC5bqJpN_DNL02AAshbRn7P2BuKw_MYT9tK-3IAuCo7sgbIlWG5Z6aeVGKE/s1600/moon2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhidpTzDwnrDmkx0IlsEH8UBZSI1GDtrE1BjTQz1rxlPrchB6NSLwX4tMuNzGqgLmlFBIiLXV5V4DZh9OpOcC5bqJpN_DNL02AAshbRn7P2BuKw_MYT9tK-3IAuCo7sgbIlWG5Z6aeVGKE/s320/moon2.gif" width="320" /></a></div>
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Enceladus, Saturn's small but surprisingly active moon with huge space geysers!<br />
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Mimas, Saturn's "Death Star" moon (unfortunately I can't capture its geoid or topographic relief ... yet).<br />
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Iapetus, Saturn's starkly two-toned moon (this animation does not capture its equatorial ridge).<br />
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<a href="http://www.blogger.com/blogger.g?blogID=3875399461809136780" name="triton"></a>Triton, largest moon of Neptune. The map of Triton remains incomplete (our only high-resolution data is from the 1989 Voyager 2 flyby), so I focused this render on the hemisphere that was mapped. I say we go back and finish the job!<br />
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Enceladus, Mimas, Iapetus, and Triton maps all sourced from <a href="http://laps.noaa.gov/albers/sos/sos.html.050325" target="_blank">here</a>.<br />
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<a href="" name="mercury"></a>Finally, here's a moon-sized (smaller than both Ganymede and Titan) planet - Mercury! I combined a partial enhanced-color map with a more complete black-and-white map to fill in the gaps.<br />
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<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com5tag:blogger.com,1999:blog-3875399461809136780.post-9345257438493396562013-04-26T15:56:00.004-07:002013-05-01T14:54:53.384-07:002011 HM₁₀₂: A new companion for Neptune<div class="separator" style="clear: both; text-align: justify;">
This month my <a href="http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1210.4549" target="_blank">latest paper made it to print in the Astronomical Journal.</a> It's a short piece that describes a serendipitous discovery that my collaborators and I made while searching for a distant Kuiper Belt Object for the New Horizons spacecraft to visit after its 2015 Pluto flyby. Last October, at the annual American Astronomical Society Division of Planetary Sciences meeting, I gave a talk about this neat little object we discovered. Now that the paper is out, I thought it might be interesting and fun to assemble a blog post around the slides I prepared for that talk. So without further ado, I give you:</div>
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So, what kind of serendipitous discovery did we make? We found a Neptune Trojan, now called 2011 HM102! And it's not just any Neptune Trojan: it makes a list of superlatives. It's the <b><i>largest</i></b> trailing Trojan known in the <i>entire Solar System</i>, it's the <i><b>most inclined</b> </i>Neptune Trojan known, and (as of <i>right now</i>) it is the <i><b>closest known object of any kind</b></i> to the New Horizons spacecraft! Read on to learn about how we found 2011 HM102 and what we have learned about this remarkable little world.</div>
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Trojans in the Solar System</h4>
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Trojan asteroids are objects in 1:1 mean-motion resonance with a planet, meaning that they orbit with (nearly) exactly the same period as the planet. There are different semi-stable orbital configurations for objects in 1:1 mean-motion resonance, and Trojans are objects which fall into two of these configurations - namely, they lead or trail the planet in its orbit by (on average) about 60 degrees. Objects leading the planet oscillate around the planet-Sun L4 Lagrange point, while objects trailing the planet oscillate around the planet-Sun L5 Lagrange point. This kind of orbital oscillation is called "libration."</div>
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Jupiter was the first planet discovered to have a Trojan population, but over the subsequent decades planetary astronomers have turned up Trojans for Earth, Mars, Neptune, and Uranus as well. Earth and Uranus both only have one known Trojan each, while Mars has a handful.</div>
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Jupiter's population of Trojans, on the other hand, is quite large: the Minor Planet Center lists over 5000 known objects in the planet's L4 and L5 swarms, and it's estimated that the total number of objects in Jupiter's Trojan swarms is about equal to the total number of objects in the Main Asteroid Belt between Mars and Jupiter (somewhere around a million objects larger than 1 kilometer across). </div>
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The distant ice-giant Neptune has nine known stable Trojans. While at first glance it might seem that since we know of more than 5000 Trojan companions for Jupiter and only nine for Neptune, we can give Jupiter the award for <i>"biggest Trojan swarms."</i> Not so fast! Neptune is much farther away from us than Jupiter, and it is much harder to detect small objects (like Trojans) at Neptune's distance than it is at Jupiter's. Early estimates correcting for this effect indicate that Neptune's Trojan swarms may have upwards of <i><b>10 times</b></i> as many objects in them as Jupiter's swarms, or equivalently <i><b>10 times</b></i> as many objects as reside in the Main Asteroid Belt.</div>
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So Neptune is no slouch when it comes to Trojans! The trick is <i>finding</i> these distant, slow-moving, and <i>exceedingly</i> faint objects. Which brings us to...</div>
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Our search</h4>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhB6zuIp5YPi_CM_t5mDILR3YsS7N32inpOUrpa9WSF8ibUAAiGzeHjCPXeK8C9fh0BGJk7dXNN7kibEnWYRRSLlUSYG6nxXTWUN4BxGFQx9muyC2Lbf9LGoAYAUnMTDLFIo3XvX2fA1hw/s1600/DPS_Parker2012.002.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: left;"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhB6zuIp5YPi_CM_t5mDILR3YsS7N32inpOUrpa9WSF8ibUAAiGzeHjCPXeK8C9fh0BGJk7dXNN7kibEnWYRRSLlUSYG6nxXTWUN4BxGFQx9muyC2Lbf9LGoAYAUnMTDLFIo3XvX2fA1hw/s640/DPS_Parker2012.002.png" width="640" /></a></div>
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Why were we at the telescope when we found 2011 HM102? Well, we have a spacecraft in need of a world to visit!</div>
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New Horizons is currently flying out to meet Pluto at a breakneck speed of over 13 kilometers per second. In July of 2015, it will fly through the Pluto system, collecting as much data as it can with its onboard instruments, and then beam all that information back to Earth. However, there's no stopping New Horizons at Pluto. The spacecraft will continue outward into the Kuiper Belt at that incredible speed, with enough fuel left onboard for a small course change.</div>
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Our goal is to find a small Kuiper Belt Object (KBO) for New Horizons to study once it has completed its primary mission to Pluto. Because of its limited remaning fuel supply, it can only make a small course change, meaning that it can only reach a very small slice of the outer Solar System. However, the outer Solar System is filled with billions of small, icy objects, so we set out to find New Horizons the perfect candidate.</div>
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Why didn't we simply look into the catalogs of known KBOs and pick one for New Horizons to visit? Unfortunately, all the KBOs that would be accessible to New Horizons fall in an area of sky that has been very poorly searched for KBOs to-date: the Galactic plane, near the heart of Sagittarius. As any amateur astronomer knows, this area of sky is beautiful through a small telescope for precisely the same reason that it is a terrible place to search for faint moving specks like KBOs - it's absolutely <i>packed</i> with stars!</div>
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Astronomers conducting surveys for KBOs usually pick fields far away from the Galactic plane to avoid dealing with images filled to the brim with <i>boring old stars</i>. So, unfortunately, that means we had to do our own survey, and <i>we</i> got to deal with the nightmare that is dredging through these starfields for moving objects. Good thing we enjoy challenges.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhntnCMbkhNu3g4V3D1JpTAo3FOpehHJpN-P2bM_YDMh3aYe1DB1yfXdPNhiUflUugEMOs2YWem1qmeG0XwKmRRHTdDoZEMZ1OC82bRU61XekBN_rxBQhCkAiFtm_7xa6toRc5fumYBrMM/s1600/DPS_Parker2012.004.png" imageanchor="1"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhntnCMbkhNu3g4V3D1JpTAo3FOpehHJpN-P2bM_YDMh3aYe1DB1yfXdPNhiUflUugEMOs2YWem1qmeG0XwKmRRHTdDoZEMZ1OC82bRU61XekBN_rxBQhCkAiFtm_7xa6toRc5fumYBrMM/s640/DPS_Parker2012.004.png" width="640" /></a></div>
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Above is an actual image from one of our survey runs, taken at one of the twin Magellan telescopes in Chile. As you can see, the field we have to target is full of stars much brighter than our target Kuiper Belt Objects (KBOs).<br />
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So how are we managing to find our wily little specks? First off, we need a <i>lot</i> of light-collecting power, so we need some of the largest telescopes in the world. Second, we have a relatively large area of sky to search - roughly 8-10 times the size of the full moon - so we need <i>big imagers</i>.</div>
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That limits the facilities we can use to just a few; the 3.5 meter Canada-France-Hawaii telescope (CFHT) with its huge MegaPrime imager, the twin 6.5 meter Magellan telescopes with their three large-format imagers (IMACS f/2, IMACS f/4, and MegaCam), and the enormous 8.2 meter Subaru telescope with its SuprimeCam imager.</div>
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This schematic shows the relative sizes of these facilities' primary mirrors (drawn to scale with a human figure) and the relative sizes of each imagers' field-of-view (compared to the apparent size of the full moon on the sky). </div>
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Starting in 2011, we have been turning these telescopes and their giant imaging arrays toward the patch of sky were we expect to find the Kuiper Belt objects that New Horizons can reach.</div>
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Once we have collected the images, we go to work on them. We apply special techniques that remove stationary objects (like stars) and reveal moving objects (like Kuiper Belt objects). Here's an example of image data from a previous survey (from a less-crowded starfield) in three stages of this filtering process, leaving behind only one (moving) object, an asteroid:</div>
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It's hard work, but does it get the job done? Yes!</div>
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Since the beginning of our search in 2011 we have discovered nearly 30 new KBOs, many of which come exceedingly close to New Horizons' trajectory. Here's an animation I made to show these objects (as well as objects from a precursor survey performed in 2004-2005) as seen by New Horizons as it flies through the outer Solar System:</div>
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<a href="http://vimeo.com/45883622">New Horizons Mission: Kuiper Belt Fly-Through</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.</div>
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So we're turning up lots of new KBOs out beyond Pluto. But perhaps you noticed that there was one object that flew by <i>well before</i> New Horizons got to Pluto? </div>
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Discovery of 2011 HM102</h4>
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Our survey beam punches right through Neptune's trailing Trojan cloud. We did not design our survey specifically to find Neptune Trojans - though we were aware that we <i>could</i> find them. </div>
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Above is an illustration of our survey's beam through the plane of the solar system, targeting distant, encounterable Kuiper Belt Objects. This targeting coincidentally passes right through Neptune's trailing L5 Trojan cloud. White points indicate objects discovered by our survey. Also illustrated are the Pluto system, New Horizons, and 2008 LC18 (the only other known stable L5 Neptune Trojan).</div>
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During the normal search process, we spotted 2011 HM102 as fast-moving and very bright - it's the brightest object we've discovered to date by a wide margin. </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE7hIQcmjL3-KDhqaZbZSD3Tu1xjQvU-Yz8C2O6o9DZAHs1gZm6580LIx2jG5MghGKyYvZQ4MNMexVTZgaJ6ckwFCj0b6-2SkjT-CKWJuWRpnppAN2wFEY-S1cEBy85Lfq7cnwpvC9FXM/s1600/5oe7.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE7hIQcmjL3-KDhqaZbZSD3Tu1xjQvU-Yz8C2O6o9DZAHs1gZm6580LIx2jG5MghGKyYvZQ4MNMexVTZgaJ6ckwFCj0b6-2SkjT-CKWJuWRpnppAN2wFEY-S1cEBy85Lfq7cnwpvC9FXM/s400/5oe7.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Discovery images of 2011 HM102, without stars removed.</td></tr>
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We also quickly realized that it had a very high inclination of about 30 degrees. Because it was so bright, close, and highly inclined, we decided to devote a little follow-up time to it the following year. Those follow-up observations allowed us to really nail-down its orbit and determine that it was, in fact, a Neptune Trojan.</div>
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At the same time, the <a href="https://www.zooniverse.org/project/icehunters" target="_blank">Ice Hunters</a> were analyzing a subset of our data using the sheer power of thousands of human eyeballs. They easily spotted 2011 HM102 independently of us, and became co-discoverers. You can find a list of all those Ice Hunters who spotted 2011 HM102 in <a href="http://www.minorplanetcenter.net/mpec/K12/K12T05.html" target="_blank">the discovery MPEC. </a><br />
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Using the updated orbit, I ran a large number of simulations to determine how stable 2011 HM102 was, and found that for at least a billion years, 2011 HM102 happily continues to remain in its resonant configuration with Neptune.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsTeP6jloTduSZSUWW8ZX-qBYm_1dOolQqtbsAe0EQmzqQJddFep2ig4EsW95PgoMNMPOg30SyY-mUKc2SL2RicTilo6mqVeBYVc1i1SshWlqXOhqqjxGPNMAld1QVuGmFXWwl5ACpK4M/s1600/DPS_Parker2012.007.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: left;"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsTeP6jloTduSZSUWW8ZX-qBYm_1dOolQqtbsAe0EQmzqQJddFep2ig4EsW95PgoMNMPOg30SyY-mUKc2SL2RicTilo6mqVeBYVc1i1SshWlqXOhqqjxGPNMAld1QVuGmFXWwl5ACpK4M/s640/DPS_Parker2012.007.png" width="640" /></a></div>
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<span style="text-align: justify;">Since we were now confident it was a true L5 Neptune Trojan, we could compare it to the other Trojans. 2011 HM102's high inclination (29.4 degrees) is higher than any other known Neptune Trojan, and only a few percent of Jupiter's Trojans have higher inclinations. In addition, it's as bright or brighter than Jupiter's largest L5 Neptune Trojan Patroclus, which is a binary. If 2011 HM102 is a single object, and its albedo is similar to Patroclus, then it is the largest known L5 Trojan in the solar system.</span></div>
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Because 2011 HM102 is quite bright (compared to the other objects we had been finding), we could also measure it's color. This is done by collecting images of the object through various color filters, and comparing how bright it appears in one color filter versus another. This was the first measurement of the color of a trailing Neptune Trojan, and we demonstrated that it has a very similar color to the leading Neptune Trojans.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoXijpv5yxC23Q8OGD54xZBNJVI_TT7gLSL2xVPABXQVKSbv9x0iu6r6ZdNK2efqThurSDEPxzB3iqFo24RbhOrN36amD1fCuh29HFgRKj_Jdnk-FHIIw7h0LAukGdDFEYQJqUswJ9N1U/s1600/DPS_Parker2012.009.png" imageanchor="1"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoXijpv5yxC23Q8OGD54xZBNJVI_TT7gLSL2xVPABXQVKSbv9x0iu6r6ZdNK2efqThurSDEPxzB3iqFo24RbhOrN36amD1fCuh29HFgRKj_Jdnk-FHIIw7h0LAukGdDFEYQJqUswJ9N1U/s640/DPS_Parker2012.009.png" width="640" /></a></div>
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<br />
Above is a color-color diagram showing 2011 HM102. The X-axis is a "Blue" (B) minus a "Red" (R) color, with redder objects appearing on the right. The Y-axis is a "Sort of yellow" (V) minus a "Very near infrared" (I) color, with redder objects appearing toward the top. The color of the Sun falls in the lower-left, marked by the star - most outer solar system objects are redder than the Sun. 2011 HM102 and other Neptune Trojans share similar colors, and are similar to the Jupiter Trojans.<br />
<br />
We recognized one other interesting aspect about 2011 HM102: it comes fairly close to New Horizons! As of right now, it is the closest known object of any kind to New Horizons - about 2.5 AU away. In the later parts of 2013, it will pass within 1.2 AU of New Horizons, where it will be bright enough to be just detectable from New Horizons.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDcU7sr5EyS_tG-oGiP65rZeDMoqZeILRO6KlrGzn27U1KPX3Lcv4Jqcubt71CG-_4pbYJmKt2T9i_Ot7M6M3wjShTG_4bMdrX-W4aiLzQ96kLSEuhWsx1iyzTGnaDoI_mXgd1Ewfbcu0/s1600/DPS_Parker2012.010.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: left;"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDcU7sr5EyS_tG-oGiP65rZeDMoqZeILRO6KlrGzn27U1KPX3Lcv4Jqcubt71CG-_4pbYJmKt2T9i_Ot7M6M3wjShTG_4bMdrX-W4aiLzQ96kLSEuhWsx1iyzTGnaDoI_mXgd1Ewfbcu0/s640/DPS_Parker2012.010.png" width="640" /></a></div>
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While the New Horizons team decided that they would not target 2011 HM102 for observations (as the preparations for the Pluto approach take precedence), I still think 2011 HM102 represents something of a Rubicon. This is the first known, small trans-Neptunian object that New Horizons will pass, symbolically marking its entrance into trans-Neptunian space.</div>
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<br />
Finally, I leave you with an animation of the motion of 2011 HM102.<br />
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<div style="text-align: center;">
<iframe allowfullscreen="" frameborder="0" height="281" mozallowfullscreen="" src="http://player.vimeo.com/video/50662184" webkitallowfullscreen="" width="500"></iframe> </div>
<div style="text-align: center;">
<a href="http://vimeo.com/50662184">2011 HM102 - An L5 Neptune Trojan</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.</div>
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<br /></div>
<div style="text-align: justify;">
There are a few more interesting facets to 2011 HM102 and how it fits into the Neptune Trojan population as a whole... but those will have to wait until my next paper is published!</div>
Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com2tag:blogger.com,1999:blog-3875399461809136780.post-34151958581037903522013-04-18T17:49:00.002-07:002013-04-26T16:06:34.110-07:00Flying from Kepler-62 e to Kepler-62 fToday NASA announced the discovery of two potentially-habitable planets orbiting a single star. The star is designated Kepler-62, and these two planets are referred to by their place in the five-planet system - <i>e</i> is planet four and <i>f</i> is planet five (<i>a</i> is reserved for the host star).<br />
<br />
These planets are both quite small - 1.4 and 1.6 times the radius of the Earth, respectively. In addition, they're both located at relatively comfortable distances from their host star. Depending on what their atmospheres are like, they could potentially host conditions on their surfaces that are amenable to life.<br />
<br />
But <i>two</i> planets in (or near) a single star's habitable zone? That made me wonder - if a civilization arose on one of the two planets, how difficult would it be for them to visit the other planet?<br />
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<a name='more'></a><br />
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It's pretty easy to work out the change in speed needed to make the most efficient direct hop between two near-circular planetary orbits (as long as you're doing nothing fancy like gravitational assists, solar sails, or ion engines). I've illustrated what such an orbit (called a <a href="http://en.wikipedia.org/wiki/Hohmann_transfer_orbit" target="_blank">Hohmann Transfer Orbit</a>) would look like between Kepler 62 <i>e</i> and <i>f</i> - this is very similar to the trajectory that we use to send our orbiters and landers from Earth to Mars.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIGvP2cijbMP6VggfYc-ZkSEpbPCOl6RG9F9RdncZCRMxlCYywufatIFD_np8QdewPh05_EOT2EKy2KfAJWUJpgznzO68TUhpcRr0DE1dImpTknUFyP9wp7JMd3sHNfXZwHy2wtKMgwBs/s1600/fig1_kepler62.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIGvP2cijbMP6VggfYc-ZkSEpbPCOl6RG9F9RdncZCRMxlCYywufatIFD_np8QdewPh05_EOT2EKy2KfAJWUJpgznzO68TUhpcRr0DE1dImpTknUFyP9wp7JMd3sHNfXZwHy2wtKMgwBs/s640/fig1_kepler62.png" width="640" /></a></div>
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<br />
This transfer orbit's <a href="http://en.wikipedia.org/wiki/Semi-major_axis" target="_blank">semi-major axis</a> (<i style="font-weight: bold;">a</i><span style="font-size: xx-small;">ship</span>) is given by the average of the semi-major axes of the two planets (<i style="font-weight: bold;">a</i><span style="font-size: xx-small;">e </span>and <i style="font-weight: bold;">a</i><span style="font-size: xx-small;">f</span>):<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPwphW3PgEcFFvdxaIKBW7PHzzzoXLyEGNm_jtJ_3wRLNXt79M_O9-ql1dx3oTk3Zp-xppSKrM6cy4N9NzZgQGd0WI97ZsrM8VuhShd0XlFpAmPxYhtf_AlL3dyhC6oQ20DNIAMqQfMAE/s1600/Eqn1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPwphW3PgEcFFvdxaIKBW7PHzzzoXLyEGNm_jtJ_3wRLNXt79M_O9-ql1dx3oTk3Zp-xppSKrM6cy4N9NzZgQGd0WI97ZsrM8VuhShd0XlFpAmPxYhtf_AlL3dyhC6oQ20DNIAMqQfMAE/s200/Eqn1.png" width="200" /></a></div>
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Once we have that, and we know a few things about the star the planets are orbiting, we can calculate the speed that a ship leaving planet <i>e</i> would need in order to reach planet <i>f</i> via this type of orbit. To get this, we can use the <a href="http://en.wikipedia.org/wiki/Vis-viva_equation" target="_blank">vis viva equation</a> to find the orbital speed of a hypothetical ship on the transfer orbit when leaving planet <i>e</i>, then subtract off the orbital speed of planet <i>e</i> itself (since any ship launched would already be moving at the speed of the planet, and we're interested in how much <i>more</i> speed a rocket would need to give it):<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrJdzaJ4OC_7RPu6w0BkuREmNC09GfJ0jG4eDZHpCvxFeTx7XiFF0vjjhgBO1KQfhxfAI-XSyu_3tPVp1GffChcipBrSYxi97ufxWeLc-McCb8CGE72zgjR6TQoeJICsCQDwi2F5Bd3rw/s1600/Eqn2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="118" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrJdzaJ4OC_7RPu6w0BkuREmNC09GfJ0jG4eDZHpCvxFeTx7XiFF0vjjhgBO1KQfhxfAI-XSyu_3tPVp1GffChcipBrSYxi97ufxWeLc-McCb8CGE72zgjR6TQoeJICsCQDwi2F5Bd3rw/s400/Eqn2.png" width="400" /></a></div>
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Where <i style="font-weight: bold;">G</i> is the gravitational constant and <i style="font-weight: bold;">M</i><span style="font-size: xx-small;">*</span> is the mass of the host star.<br />
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From the <a href="http://www.sciencemag.org/content/early/2013/04/17/science.1234702.abstract?sid=9d84a3af-fee9-4871-916b-2e10eb5a5998" target="_blank">discovery paper</a>, we can collect the values of <i style="font-weight: bold;">a</i><span style="font-size: xx-small;">e</span>, <i style="font-weight: bold;">a</i><span style="font-size: xx-small;">f</span>, and <i style="font-weight: bold;">M</i><span style="font-size: xx-small;">*</span>:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhruseJ4YBBD6_r37ERBL1mZW5dSV3fKvIqEVLgJrafKSPgg0v6w6LWY9P2RxELSZpHkuThxpS3ZDd-Duf8pxmHerGayqrvYIzG1mmpDTMu58TTqfSUJFZYSP0C6MSpt6T-PPimhCrmSHo/s1600/Eqn3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="70" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhruseJ4YBBD6_r37ERBL1mZW5dSV3fKvIqEVLgJrafKSPgg0v6w6LWY9P2RxELSZpHkuThxpS3ZDd-Duf8pxmHerGayqrvYIzG1mmpDTMu58TTqfSUJFZYSP0C6MSpt6T-PPimhCrmSHo/s200/Eqn3.png" width="200" /></a></div>
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So if we plug in these values (and the value of <i style="font-weight: bold;">G</i> with the correct units), we find a velocity of about <a href="https://www.google.com/search?q=sqrt(+(+2%2F(0.427+AU)+-+2%2F(0.427+AU+%2B+0.718+AU)+)+*+(0.69*(+1.9891E30+kg+)+*+G+)+%3D" target="_blank">42.4 kilometers per second</a> for the first term, and about <a href="https://www.google.com/search?q=sqrt(+0.69*(+1.9891E30+kg+)+*+G+%2F+(0.427+AU)+)" target="_blank">37.9 kilometers per second</a> for the second term. Therefore, a rocket sending a ship from <b>Kepler-62 <i>e</i> to Kepler-62 <i>f</i></b> would need to impart the difference, or about <b>4.5 kilometers per second.</b><br />
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Now we need some context - is 4.5 kilometers per second a lot? Let's compare it to the speed needed for a ship leaving Earth to reach Mars by the same type of orbit: all we have to do is substitute the <a href="http://en.wikipedia.org/wiki/Solar_mass" target="_blank">Sun's mass</a> for <i style="font-weight: bold;">M</i><span style="font-size: xx-small;">*</span>, Earth's semi-major axis (1 AU) for <i style="font-weight: bold;">a</i><span style="font-size: xx-small;">e</span> and Mars' semi-major axis (1.52 AU) for <i style="font-weight: bold;">a</i><span style="font-size: xx-small;">f</span>. Plugging these in, we find about <a href="https://www.google.com/search?q=sqrt(+(+2%2F(1+AU)+-+2%2F(1+AU+%2B+1.52+AU)+)+*+(+(+1.9891E30+kg+)+*+G+)+%3D" target="_blank">32.7 kilometers per second</a> for the first term and about <a href="https://www.google.com/search?q=sqrt(+(+1.9891E30+kg+)+*+G+%2F+(1+AU)+)" target="_blank">29.8 kilometers per second</a> for the second term. So a rocket boosting a ship from <b>Earth to Mars</b> on this kind of transfer orbit would need to add about <b>2.9 kilometers per second.</b><br />
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So that means that a ship leaving Kepler-62 <i>e</i> for Kepler-62 <i>f</i> needs <b>55% more initial speed</b> than a ship leaving Earth for Mars. <b>Ouch.</b><br />
<br />
But stay positive, you hypothetical planetary explorers from Kepler-62 <i>e</i>: just because it takes more <i>oomph</i> to get from Kepler-62 <i>e</i> to Kepler-62 <i>f</i> doesn't mean it's impractical! We've explored lots of places in our solar system that required more <i>oomph</i> than getting from Earth to Mars. In fact, <a href="http://en.wikipedia.org/wiki/Dawn_(spacecraft)" target="_blank">NASA's Dawn spacecraft</a> just finished exploring the asteroid Vesta (which orbits between Mars and Jupiter), and getting from Earth to Vesta on a Hohmann transfer orbit would require almost exactly the same initial speed as getting from Kepler-62 <i>e</i> to Kepler-62 <i>f!</i> Dawn took a very different trajectory, however; it rode out on low-thrust (but extremely efficient) ion engines, and it has now lit those engines up again to fly onward to the dwarf planet Ceres.Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com1tag:blogger.com,1999:blog-3875399461809136780.post-66122502639977035072013-04-02T15:48:00.001-07:002013-04-30T20:38:14.198-07:00#NaPoWriMo<b>Day 30: Until next time.</b><br />
<u><strike><br /></strike></u>
<br />
Thirty days written:<br />
Worlds in words with friends in prose<br />
under spring skies.<br />
<br />
<u><strike> </strike></u><br />
<b><br /></b>
<b>Day 29: Challenge</b><br />
<b><br /></b>
<br />
not lost.<br />
simply unseen.<br />
out in the deep star-fields<br />
slow-plying, so come, look again:<br />
find me.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 28: Zeroth Order</b><br />
<div class="p2">
<br /></div>
<div class="p1">
scratch a few </div>
<div class="p1">
marks on a page</div>
<div class="p1">
trace the big picture</div>
<div class="p1">
in broad strokes</div>
<div class="p1">
with small lines</div>
<div class="p2">
<br /></div>
<div class="p1">
nevermind the human</div>
<div class="p1">
ephemera</div>
<div class="p1">
that fills each <i>dt</i></div>
<div class="p1">
no matter how minute</div>
<div class="p2">
<br /></div>
<div class="p1">
they fall out trivially</div>
<div class="p1">
in the end</div>
<div class="p1">
anyway.</div>
<b><br /></b>
<b></b><br />
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<b>Day 27: #fundPlanetary</b><br />
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<b>Day 26: Nine+</b><br />
<div class="p1">
<br />
<div class="p2">
So small<br />
yet so diverse<br />
defying conventions<br />
stealing our planet-centric hearts<br />
away.</div>
</div>
<br />
<u><strike> </strike></u><br />
<br />
<b>Day 25: Eight</b><br />
<div class="p1">
<br />
<div class="p2">
Cold king</div>
<div class="p2">
Of distant fields.</div>
<div class="p2">
Do your subjects love you</div>
<div class="p2">
Or do they fear your powerful,</div>
<div class="p2">
Harsh hand?</div>
<br /></div>
<u><strike> </strike></u><br />
<b><br /></b>
<b>Day 24: Seven</b><br />
<div class="p1">
<br />
Your stance:<br />
<div>
<div class="p1">
Unorthodox,</div>
<div class="p1">
Yet bold, brash, and daring.</div>
<div class="p1">
But does it match your character's</div>
<div class="p1">
Content?</div>
</div>
</div>
<br />
<u><strike> </strike></u><br />
<br />
<div class="p1">
<b>Day 23: Six</b></div>
<br />
<div class="p1">
Don't judge.</div>
<div class="p1">
We know we're not</div>
<div class="p1">
Dressed for this neighborhood.</div>
<div class="p1">
But we just can't afford the rings</div>
<div class="p1">
You flaunt.</div>
<br />
<div class="p1">
</div>
<u><strike> </strike></u><br />
<br />
<div class="p1">
<b>Day 22: Five</b></div>
<br />
<div class="p1">
Anger</div>
<div class="p1">
Is evident</div>
<div class="p1">
On your storm-shrouded brow.</div>
<div class="p1">
Did our grand envoy's final plunge</div>
<div class="p1">
Offend?</div>
<div class="p1">
<br /></div>
<div class="p1">
</div>
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<br />
<div class="p1">
<b>Day 21: Four</b></div>
<br />
<div class="p1">
So small</div>
<div class="p1">
For such mountains,</div>
<div class="p1">
Flood-valleys, and war scars.</div>
<div class="p1">
You must have such stories; will you</div>
<div class="p1">
Share them?</div>
<br />
<div class="p1">
</div>
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<br />
<div class="p1">
<b>Day 20: Three</b></div>
<br />
<div class="p1">
Blue-green,</div>
<div class="p1">
Dappled with white.</div>
<div class="p1">
Turning with your ash-pale</div>
<div class="p1">
Companion and your wine-dark seas;</div>
<div class="p1">
Just right.<br />
<br /></div>
<div class="p1">
</div>
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<br />
<div class="p1">
<b>Day 19: Two</b></div>
<br />
<div class="p1">
You look</div>
<div class="p1">
A lot like us</div>
<div class="p1">
At first glance, but hot like</div>
<div class="p1">
Countless scattered stars, though none burn</div>
<div class="p1">
So bright.</div>
<div class="p1">
<br /></div>
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<br />
<div class="p1">
<b>Day 18: One</b></div>
<div class="p1">
<b><br /></b></div>
<div class="p1">
Fleeting</div>
<div class="p1">
At dawn and dusk;</div>
<div class="p1">
impermanence defined.</div>
<div class="p1">
Stone, fire, and gravity assault;</div>
<div class="p1">
you hold.</div>
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 17: Delivery</b><br />
<br />
Oceans -<br />
brought frozen<br />
in countless tiny shards,<br />
infused with exotic flavors.<br />
Aged to perfection<br />
with silt and salt<br />
and life.<br />
<br />
<div class="p1">
</div>
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 16: Fine Petals </b><br />
<br />
<div class="p1">
There's a rare nocturnal flower </div>
<div class="p1">
that's most oft found high and dry;</div>
<div class="p1">
their fine petals open nightly, </div>
<div class="p1">
and they look up to the sky.<br />
<br /></div>
<div class="p1">
They await some distant pollen, </div>
<div class="p1">
carried cross a dark abyss</div>
<div class="p1">
in the gentle winds of starlight, </div>
<div class="p1">
that alight here like a kiss.</div>
<div class="p1">
<br />
As the dawn arrives they shyly </div>
<div class="p1">
close their petals once again.</div>
<div class="p1">
They turn modest in the sun's glare,</div>
<div class="p1">
and conceal what they contain.</div>
<div class="p1">
<br />
These rare nocturnal flowers</div>
<div class="p1">
have roots that span the world</div>
<div class="p1">
that share what they've collected</div>
<div class="p1">
while their petals were unfurled.</div>
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 15: Plight of the Observer, Me</b><br />
<div>
<b><br /></b></div>
<div class="p1">
Bias, flat, dark, exposure;</div>
<div class="p1">
I've come to collect some faint starlight</div>
<div class="p1">
from within the dome enclosure.</div>
<div class="p2">
<br /></div>
<div class="p1">
It's getting late and I lose composure</div>
<div class="p1">
my scripts have failed to take the right</div>
<div class="p1">
Bias, flat, dark, exposure.</div>
<div class="p2">
<br /></div>
<div class="p1">
The sky has not yet clouded over,</div>
<div class="p1">
but I've not collected a useful byte</div>
<div class="p1">
from within the dome enclosure.</div>
<div class="p2">
<br /></div>
<div class="p1">
I re-read the manual, cover to cover,</div>
<div class="p1">
and hope I can resume tonight:</div>
<div class="p1">
Bias, flat, dark, exposure.</div>
<div class="p2">
<br /></div>
<div class="p1">
... but I might more easily land a rover</div>
<div class="p1">
on Mars than make this instrument recite</div>
<div class="p1">
"Bias, flat, dark, exposure"</div>
<div class="p1">
from within the dome enclosure.</div>
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 14: Recycled </b><br />
<br />
Little<br />
unused exists.<br />
Worlds are built in decay;<br />
shadows are haunted by countless<br />
dead stars.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 13: (Birthday) Haiku Saturday</b><br />
<br />
Two-score and twelve π<br />
radians around the sun;<br />
I'm not dizzy yet!<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 12: Yuri's Night</b><br />
<br />
<span style="font-family: inherit;">Five Vostok engines </span><br />
<span style="font-family: inherit;"> burning bright,</span><br />
<span style="font-family: inherit;"><br />
bellowing intent, </span><br />
<span style="font-family: inherit;"> begin their flight.</span><br />
<span style="font-family: inherit;"><br />
One hundred eight minutes, </span><br />
<span style="font-family: inherit;"> with ground commanding,</span><br />
<span style="font-family: inherit;"><br />
from <i>"Poehali!"</i></span><br />
<span style="font-family: inherit;"> to Sharik's landing.</span><br />
<span style="font-family: inherit;"><br />
Now a line is crossed, </span><br />
<span style="font-family: inherit;"> however time goes by;</span><br />
<span style="font-family: inherit;"><br />
There will never be a human race </span><br />
<span style="font-family: inherit;"> that did not breach the sky.</span><br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 11: </b><br />
<div style="text-align: center;">
<b>The Dark</b></div>
<b><br /></b>
<br />
<div style="text-align: center;">
Content at night</div>
<div style="text-align: center;">
the dark areas agree</div>
<div style="text-align: center;">
a symbiosis</div>
<div style="text-align: center;">
in cold resistance</div>
<div style="text-align: center;">
to different forms,</div>
<div style="text-align: center;">
different conditions,</div>
<div style="text-align: center;">
<br /></div>
<div style="text-align: center;">
to prevail</div>
<div style="text-align: center;">
<br /></div>
<div style="text-align: center;">
in the dark.</div>
<div style="text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnRmbXm3HkM-wBZM6_IVlaeLX3fnKZx6HMZDq-h8YsC_Ox9bblkQxcxcdUPixcLwZzd8gBeFp9LpFKWsYc1Aci68JTBPr3U3od1y1XNBiot6RVOOsCeVCyW-Ix1In_1v9Yj6optsqoASI/s1600/redact2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnRmbXm3HkM-wBZM6_IVlaeLX3fnKZx6HMZDq-h8YsC_Ox9bblkQxcxcdUPixcLwZzd8gBeFp9LpFKWsYc1Aci68JTBPr3U3od1y1XNBiot6RVOOsCeVCyW-Ix1In_1v9Yj6optsqoASI/s640/redact2.jpg" width="419" /></a></div>
<br />
<i>Page 267 from "The Physics of the Planet Mars" by Gerard de Vaucouleurs, 1953.</i><br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 10: And his name was Murphy.</b><br />
<br />
<div class="p1">
There once was a man from El Paso</div>
<div class="p1">
who went into space with a lasso</div>
<div class="p1">
to bag a big rock</div>
<div class="p1">
and bring it back to dock</div>
<div class="p1">
but it missed and caused quite a fiasco.</div>
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 9: Innermost</b><br />
<br />
Swing close and hotly, deep in twilight glare,<br />
between the prowling nickel Scylla's gaze<br />
and whirling end sunlight's Charybdis brings<br />
to those too small, who weakly fight her force.<br />
So hide, obscure, amongst the fading wings<br />
of Icarian ice, now stripped and set ablaze -<br />
but know; our sleepless eyes will find you there,<br />
unless ... unless you <i>are</i> just myths, of course.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 8: The Cluster</b><br />
<br />
whirr away, minions<br />
take data and instructions<br />
leave heat and science<br />
be swift but always precise<br />
and wary of floating points .<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 7: Retrograde.</b><br />
<br />
Harsh tides<br />
A slow demise<br />
Now imperceptible<br />
Spiral down; but briefly become<br />
Bright rings.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 6: Haiku Saturday.</b><br />
<br />
Anise night enfolds;<br />
dry, but for the sage-soft rain<br />
of saffron starlight.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 5: Enter three photons.</b><br />
<br />
Tumble, tumble, you pile of rubble;<br />
boulders split, and regolith crumble.<br />
Cast off your spin and your eigenvalues,<br />
forsake your conformity and principal axis.<br />
You are freed from restriction by chaos-taboos,<br />
freed by light on your face and shape of your facets.<br />
So tumble, tumble, you pile of rubble;<br />
and thank the Sun for all it's trouble!<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 4: Sparks</b><br />
<br />
the soft green night<br />
hides its tempo<br />
in the moon-flicker<br />
through the trees.<br />
a new tone is struck<br />
for every breath<br />
on every leaf.<br />
the stars are faint<br />
yet flickers show;<br />
their beats as brief<br />
as worlds' shadows.<br />
<br />
<u><strike> </strike></u><br />
<u><strike><br /></strike></u>
<b>Day 3: Charon is a Harsh Mistress</b><br />
<br />
My Charon is a harsh mistress;<br />
and no part of her is weak.<br />
Her tides are swift and most capricious,<br />
her chaotic sea is bleak.<br />
<br />
My Charon is a harsh mistress;<br />
she demands you fools keep pace.<br />
If she sees you flag or grow too listless<br />
she will cast you out with haste.<br />
<br />
My Charon is a harsh mistress, though once a part of me,<br />
For as we are locked together, and cannot look apart<br />
I see her for what she is, and it pains my stony heart.<br />
She is filled with ice, more ice than me,<br />
and has been from the start.<br />
<br />
<u><strike> </strike></u><br />
<b><br /></b>
<b>Day 2: Feed</b><br />
<br />
<b>O</b>rigin left<br />
<b>M</b>yriad equals<br />
<b>N</b>ow few<br />
<b>O</b>ligarchs stir<br />
<b>M</b>any less-<br />
<b>N</b>otable beginnings<br />
<b>O</b>nto paths<br />
<b>M</b>ost will<br />
<b>N</b>ever escape<br />
<b>O</b>utward into<br />
<b>M</b>ere desolation<br />
<b>N</b>one welcome<br />
<b>O</b>blivion in<br />
<b>M</b>erger.<br />
<br />
<u><strike> </strike></u><br />
<b><br /></b>
<b>Day 1: Observing Proposal</b><br />
<br />
Once a glittering chord<br />
in some enduring tapestry,<br />
now an unstitched thread<br />
pulled loose for scrutiny.<br />
<br />
Who am I to tell it a warp from a weft?<br />
My eye cannot be sufficiently keen.<br />
I can only tease a new fiber free<br />
and hope it proves a sympathetic string.<br />
<br />
<u><strike> </strike></u><br />
<b><br /></b>
<b>Day 0:</b><br />
<br />
/ One<br />
/ Step<br />
// Begins<br />
/// A sequence<br />
///// Without a limit<br />
//////// Except the smallest infiniteAlex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com1tag:blogger.com,1999:blog-3875399461809136780.post-18515830102496576132013-03-18T17:29:00.000-07:002013-03-18T17:29:33.958-07:00How big do stars look from habitable planets around them?Standing on a habitable alien world, how big would that planet's host star look overhead?
After a quick Googling, I didn't come up with any nice summaries. So I snagged <a href="http://books.google.com/books/about/Allen_s_Astrophysical_Quantities.html?id=w8PK2XFLLH8C">Allen's Astrophysical Quantities</a> and did a couple quick calculations.
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjcG7q6xjeSX7v9_BzQbKYn7ECrvOm0UwTZVMwH528aUI5P2U0SEj8sndpF4lwboJBJR7UnqIVvfjD2mP3_EK_RzHi9w4lhEPXp-VWXJXoVjsG0eOiHl9h_rf6PggZE3epe2gT8z25x94/s1600/star_size.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjcG7q6xjeSX7v9_BzQbKYn7ECrvOm0UwTZVMwH528aUI5P2U0SEj8sndpF4lwboJBJR7UnqIVvfjD2mP3_EK_RzHi9w4lhEPXp-VWXJXoVjsG0eOiHl9h_rf6PggZE3epe2gT8z25x94/s640/star_size.png" width="267" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
This figure is the result, showing the apparent sizes of stars as seen from hypothetical habitable planets. around them, all scaled to the size our Sun appears in the Earth's sky. The estimates are fairly crude; I just approximated the distance at which the (bolometric) flux from each star would be equal to that which Earth sees from the Sun. This ignores complicating factors like effective albedo changes due to different peak wavelengths produced by each star, or tidal locking for close-in planets around the lowest-mass stars.</div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
I added the approximate masses of a few notable stars on the left-hand side. Only a couple of these are known to have planets. </div>
<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-221196428254346252013-03-01T17:24:00.003-08:002013-03-01T17:25:23.506-08:00New 500px photography accountI have not created any strictly photography-related posts yet. I plan remedy this soon, and to get the ball rolling I have created a 500px account to host my photography.
<br />
<br />
At this point, I have only uploaded a sample of my photography from the last few years, but feel free to peruse: <a href="http://500px.com/alexhp" target="_blank">http://500px.com/alexhp</a><br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://500px.com/photo/27184883" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://pcdn.500px.net/27184883/b7449b9e5c708f37ef51d2f9d635bac3eece5603/4.jpg" width="400" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
A couple examples below the fold.</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<a name='more'></a><br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://500px.com/photo/27184861" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://pcdn.500px.net/27184861/5f4f83eb0f7e3b3aa2ea2aaba79aeb6fff42146a/4.jpg" width="400" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://500px.com/photo/27184871" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://pcdn.500px.net/27184871/71cb8196139df29ce4059377009af2002303c96e/4.jpg" width="400" /></a></div>
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<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-40776198364273257222013-02-22T16:58:00.000-08:002013-02-22T17:01:42.566-08:00Observatory Interior: Interactive Panorama!Have you ever wondered what the inside of a world-class observatory looks like?<br />
<br />
On a run at the <a href="http://obs.carnegiescience.edu/Magellan/" target="_blank">Magellan Baade 6.5-meter</a> observatory in Chile last year, I took a full 4π steradian spherical panorama of the dome interior using <a href="http://photosynth.net/" target="_blank">Photosynth on my iPhone.</a> The result is the interactive, scrollable panorama below:<br />
<br />
<br />
<iframe frameborder="0" height="300" src="http://photosynth.net/embed.aspx?cid=7a9244c0-8925-47ad-960b-4a6c53b4c87f&delayLoad=true&slideShowPlaying=false" width="500"></iframe><br />
<br />
Below the telescope you can see two of my colleagues coming down from one of the instrument platforms; they are both well over 6' tall and make good scale references. This is a huge machine.<br />
<br />
I will post later about some of the data we collected on that run. Spoiler: Neptune has a new friend!<br />
<br />
Alex H. ParkerAlex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com1tag:blogger.com,1999:blog-3875399461809136780.post-4567336540703614842013-02-22T15:54:00.001-08:002013-02-22T16:19:48.024-08:00Planetary PopularityI have wanted to do something with the <a href="http://books.google.com/ngrams" target="_blank">Google n-gram data</a> for a while, and I've finally caved.<br />
<br />
For those who haven't seen it yet, the Google n-gram browser allows you to see and compare the historic popularity of various phrases in books throughout history.<br />
<br />
The default browser is fun and fast to play with, but I decided to take a crack at some of the raw data.<br />
<br />
How about comparing the popularity of various planets (including the now-dwarf planet Pluto) in literature across the last few hundred years?<br />
<br />
I give you "<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyeTInAxs-HSOEno-sVe7wH1StJzazcJxdRJSVcn3RNff6U5zn5gi1G_rAvbMZHxtiSSKgZSl4MzUwiA9fOUF3kqB7vXYnBy2Hn7nt4e2r8p1yY5AgBhidp5ygIK2LEojES36sa76shW0/s1600/planetary_popularity.png" target="_blank">Planetary Popularity in Recent History</a>:"<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyeTInAxs-HSOEno-sVe7wH1StJzazcJxdRJSVcn3RNff6U5zn5gi1G_rAvbMZHxtiSSKgZSl4MzUwiA9fOUF3kqB7vXYnBy2Hn7nt4e2r8p1yY5AgBhidp5ygIK2LEojES36sa76shW0/s1600/planetary_popularity.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyeTInAxs-HSOEno-sVe7wH1StJzazcJxdRJSVcn3RNff6U5zn5gi1G_rAvbMZHxtiSSKgZSl4MzUwiA9fOUF3kqB7vXYnBy2Hn7nt4e2r8p1yY5AgBhidp5ygIK2LEojES36sa76shW0/s640/planetary_popularity.png" width="224" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Click to enlarge!</td></tr>
</tbody></table>
Details and a little interpretation below the fold.<br />
<div>
<a name='more'></a><br />
In each decade after 1700, I count all mentions in books of "Planet <u> </u>" for each planet and all variations of capitalization. At each decade I then rank the planets from most to least mentions. I searched for the combination of Planet+Name to avoid possible contamination (e.g., from the element Mercury, or the goddess Venus).</div>
<div>
<br /></div>
<div>
For those planets not known in antiquity, I mark their place with a dotted line until discovery, which is marked with a circle.</div>
<div>
<br /></div>
<div>
Since Neptune was discovered mid-decade, its popularity appears to take off before discovery due to the way I smoothed the data.</div>
<div>
<br /></div>
<div>
Some very interesting trends are apparent. My favorite is the meteoric rise of the popularity of the phrase 'Planet Earth' in the early 20th century, and now Earth occupies the top spot. I think this is evidence of Earth being, for the first time, placed in a cosmic context in the public consciousness — the public realization that Earth is <i>a</i> planet, not <i>the</i> planet.</div>
<div>
<br /></div>
<div>
Its worth noting that this data goes up to 2008, so Saturn is at a bit of a disadvantage. The Cassini mission has done wonders to share the beauty of the Saturn system with the public since its arrival in 2004, so I imagine a version of this plot made in a few years' time will show a spike in Saturn's popularity.</div>
<div>
<br /></div>
<div>
Also: poor Pluto gets no love! This must be remedied! Maybe a visit from <a href="http://pluto.jhuapl.edu/" target="_blank">New Horizons</a> will help.</div>
<div>
<br />
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Alex H. Parker</div>
Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-6756414100329414312013-02-22T15:38:00.004-08:002013-02-22T23:13:02.273-08:00Accidental GeoengineeringThere are a lot of big numbers associated with climate change. The sheer scale of human activity is often lost in the numbers needed to describe it; millions, billions, and trillions.<br />
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Perhaps we need to contextualize our carbon dioxide production by comparing it to something else with similar bogglingly-big numbers: <i>space.</i><br />
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To place human greenhouse-gase production into an astronomical context, I assembled a few choice comparisons into a convenient infographic. See it below the fold.<br />
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Punchline for the impatient: we produce a <i>lot</i> of CO2. One Halley's comet every decade, and one Martian atmosphere in 200-700 years (depending on assumptions about growth).<br />
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<tr><td style="text-align: center;"><a href="http://www.astro.uvic.ca/~alexhp/new/figures/marsco2_tons.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsFPyQDd2ZLbOO57Ebq9O4XjEt7Kqvh34nKyAdL1q0yH6yxtT_Mq7O07Bo3rWFxb2L3sBM8mZC9SvryBiRm8GgfCtQ34D6ipgYcFYEXZYxh3i8GCnlH7ye5gVeRCYAwV8V559l7Bl-51Q/s1600/MarsCO2_tons.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Click to see full-size version.</td></tr>
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Alex H. ParkerAlex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-80728462199965188862013-02-22T15:26:00.004-08:002013-02-22T15:26:52.929-08:00A Golden Age for Exoplanet Discoveries<div class="separator" style="clear: both; text-align: center;">
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After making a similar plot in my <a href="https://dspace.library.uvic.ca:8443//handle/1828/3400" target="_blank">PhD thesis</a> for the discoveries of minor planets throughout history, I thought it would be interesting to compare the rate of discovery of exoplanets to that of asteroids.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKaUlDNk5IxtGfIOdEEXOIrxTvC91VXpWPH2QrBQvZC6oxpublxWhCz3F82I_RKhCYq7hpkfIX4WNs6gfGY-G236qEpb9zZs-TbSjYnUfxJR88CXqa3vIl8MTCLccZOQAVjuDIX1o-JMU/s1600/exoplanets_vs_asteroids.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKaUlDNk5IxtGfIOdEEXOIrxTvC91VXpWPH2QrBQvZC6oxpublxWhCz3F82I_RKhCYq7hpkfIX4WNs6gfGY-G236qEpb9zZs-TbSjYnUfxJR88CXqa3vIl8MTCLccZOQAVjuDIX1o-JMU/s400/exoplanets_vs_asteroids.jpg" width="400" /></a></div>
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We are clearly in a golden age of exoplanet discoveries. In the past 23 years we have discovered over 800 confirmed planets in stellar systems outside out own; it took 114 years from the discovery of Ceres to find as many asteroids.</div>
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Alex H. Parker</div>
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<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-76388160197356522962013-02-22T15:13:00.000-08:002013-02-22T15:18:33.394-08:00A Hubble Starry NightAround the time of the Hubble Space Telescope's 22nd birthday, I created an homage to its legacy by assembling the <a href="http://www.spacetelescope.org/images/archive/top100/" target="_blank">Top 100 most popular Hubble images</a> into a photomosaic of Van Gogh's famous "Starry Night" image.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://www.astro.uvic.ca/~alexhp/new/figures/starrynight_HST.thumb.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Hubble Starry Night" border="0" height="326" src="http://www.astro.uvic.ca/~alexhp/new/figures/starrynight_HST.thumb.jpg" title="Hubble Starry Night" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hubble Starry Night mosaic. Click to enlarge, or <a href="http://www.astro.uvic.ca/~alexhp/new/figures/starrynight_HST.001.jpg">view a full-size 4400x3600 version.</a></td></tr>
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Somewhat fittingly, I made this while waiting for clouds to part and reveal the stars during a night of remote observing.<br />
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I got a lot of requests to make the image available as a poster, so you can now order a print of it from <a href="http://www.zazzle.com/hubble_starry_night_24_x20_poster-228478146855479908" target="_blank">Zazzle.</a><br />
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Alex H. ParkerAlex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-91886851354872133702013-02-22T14:53:00.005-08:002013-02-22T14:55:00.537-08:00New Horizons Kuiper-Belt Fly ThroughFly with the New Horizons spacecraft as it cruises by dozens of newly-discovered Kuiper Belt Objects (KBOs) near its trajectory. These objects were found by our survey team (gray points) as well as by members of the public through Ice Hunters (purple points) during a search - still under way - to find a KBO for New Horizons to approach close enough to take detailed images and measurements of its surface. See below the break for details.
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<iframe allowfullscreen="" frameborder="0" height="281" mozallowfullscreen="" src="http://player.vimeo.com/video/45883622" webkitallowfullscreen="" width="500"></iframe> <br />
<a href="http://vimeo.com/45883622">New Horizons Mission: Kuiper Belt Fly-Through</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.<br />
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<b>Mission to Pluto and Beyond: The search for a Kuiper Belt target</b><br />
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On July 14, 2015, NASA's New Horizons spacecraft will become the first mission to visit the distant dwarf planet Pluto (2400 kilometers across) and its retinue of five moons, flying by at speeds over 50 times faster than a jet airliner.
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With its onboard reserve of fuel, New Horizons is capable of performing a small course correction after this Pluto encounter, with the aim of visiting another much smaller, frozen world deep in the Kuiper Belt. At present, however, there are no known Kuiper Belt objects which New Horizons can reach with its remaining fuel - so a search to find these targets must be performed.
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A team of scientists from across the world are making a concerted effort to identify one or more Kuiper Belt encounter targets within reach of New Horizons with its expected fuel supply in 2015. Using some of Earth's largest telescopes, we are searching the area of sky where such an encounter target would be today. This area of sky is extremely difficult to search for faint Kuiper Belt objects, owing to the fact that this region lies in the direction of the core of our Galaxy where the number of background stars is extremely high. Our team has developed a suite of advanced digital image processing algorithms for searching this data, however, and using these we have discovered a host of new Kuiper Belt objects which will fly near the spacecraft - though none yet fit within the available encounter fuel budget.
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<b>Animation Details</b>
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This animation shows the flight of the New Horizons spacecraft from 2010 to 2023 through this cloud of newly discovered Kuiper Belt Objects revealed by our search. Each KBO's position and motion has been computed from its best known orbit solution. For many objects these orbit solutions remain relatively uncertain, so the exact flyby geometry may change as we acquire new and better data.
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The yellow triangle indicates the position of the New Horizons spacecraft. The large cyan circle marks Pluto's position. The small gray points are the new Kuiper Belt Objects we discovered in the 2011-2012 observing seasons, while the purple points are new Kuiper Belt Objects discovered in 2004-2005 observing season data by members of the public through the "IceHunters" citizen science effort.
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The left panels show a top-down (i.e., from above the plane of the Earth's orbit) and side-on view of the spacecraft trajectory and the Kuiper Belt Objects discovered in our survey so far. Distance scales from the Sun are illustrated with gray lines, and the pericentric (closest point to the Sun) and apocentric (farthest point from the Sun) distances of Uranus and Neptune are marked with dashed white lines.
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The right panel shows the Kuiper Belt objects from the perspective of the New Horizons spacecraft on its actual trajectory, with the view rendered as facing directly outward from the Sun. The illustrated size of each KBO scales with distance from the spacecraft, but the sizes are not to scale (almost all of the Kuiper Belt objects so far detected will be unresolved by the instruments onboard the spacecraft). For any Kuiper Belt object which passes within 2 AU of the spacecraft, the range in AU is shown.
In the animation, a "flyby" sound is generated by the distance and flyby geometry of each object. Since there is no sound in space, this sound is there purely to enhance the impression of motion through the Kuiper Belt.
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Two long-range flybys with Kuiper Belt Objects occur before the Pluto encounter, one late 2013 and one in early 2015. It may be possible for New Horizons to make distant observations of these two objects, though neither is large enough to be resolved.
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The "cluster" of distant flybys that begins in June of 2018 is due to the passage of New Horizons into the "cold classical Kuiper Belt," a region of space densely populated by Kuiper Belt Objects.
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The hunt for ideal New Horizons encounter targets continues, and future versions of this animation will be updated as new Kuiper Belt objects are discovered.
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<b>Links</b>
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More information on the New Horizons mission:
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<a href="http://pluto.jhuapl.edu/">Mission website</a>
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<a href="http://en.wikipedia.org/wiki/New_Horizons">New Horizons Wikipedia page</a>
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Video Credits
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Alex Harrison Parker - New Horizons Outer Solar System Science Fellow, Harvard-Smithsonian Center for Astrophysics.
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The 2011-2012 New Horizons Kuiper Belt Object search team & contributors (alphabetical by first name): Alan Stern, Brian McLeod, Cesar Fuentes, Darin Ragozzine, David Borncamp, David Osip, David Tholen, David Trilling, Francesca DeMeo, Jean-Marc Petit, JJ Kavelaars, John Spencer, Lawrence Wasserman, Marc Buie, Matthew Holman, Richard Binzel, Scott Sheppard, Sebastian Fabbro, Stephen Gwyn, and Susan Benecchi. The Ice Hunters were organized by Pamela Gay, and a partial list of contributors to the 2004-2005 discoveries can be found <a href="http://minorplanetcenter.net/mpec/K12/K12FA9.html">here</a>. A full list of contributors will be forthcoming.
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[ Migrated from <a href="http://www.astro.uvic.ca/~alexhp/new/newhorizons_flythrough.html" target="_blank">original post.</a> ]Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com1tag:blogger.com,1999:blog-3875399461809136780.post-11079242725116689322013-02-22T14:48:00.003-08:002013-02-22T14:55:25.846-08:00Worlds: The Kepler Planet Candidates<iframe allowfullscreen="" frameborder="0" height="281" mozallowfullscreen="" src="http://player.vimeo.com/video/47408739" webkitallowfullscreen="" width="500"></iframe> <br />
<a href="http://vimeo.com/47408739">Worlds: The Kepler Planet Candidates</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.<br />
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This animation shows the 2299 high-quality (multiple transits), non-circumbinary transiting planet candidates found by NASA's Kepler mission so far. These candidates were detected around 1770 unique stars, but are animated in orbit around a single star. They are drawn to scale with accurate radii (in r / r* ), orbital periods, and orbital distances (in d / r*). They range in size from 1/3 to 84 times the radius of Earth. Colors represent an estimate of equilibrium temperature, ranging from 4,586 C at the hottest to -110 C at the coldest - red indicates warmest, and blue / indigo indicates coldest candidates.
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Watching in full screen + HD is recommended, so you can see even the smallest planets! Animation details below the break.<br />
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The animation is rendered with a time-step of 30 minutes, equal to the long-cadence time sample of the Kepler observatory. Three white rings illustrate the average orbital distances of Mercury, Venus, and Earth on the same scale.<br />
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When the system is animated edge-on, it is clear that there is no time during which the sample of stars the Kepler spacecraft is observing does not contain a planet transiting a star. In fact, on average there are dozens of transits occurring amongst the Kepler sample at any given instant.
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The Kepler observatory has detected a multitude of planet candidates orbiting distant stars. The current list contains 2321 planet candidates, though some of these have already been flagged as likely false-positives or contamination from binary stars. This animation does not contain circumbinary planets or planet candidates where only a single transit has been observed, which is why "only" 2299 are shown.
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I have illustrated the planet candidates as if they orbit a single star. Using a transit lightcurve, a planet's distance from a star and its radius are both measured in terms of the host stars' radius, and those relationships are preserved here. This means that for two planets of equal size, if one orbits a larger star it will be drawn smaller here. Similarly, because the orbital distances scale with the host stars' sizes, some planets orbit faster than others at a given distance from the star in the animation (when in reality, planets on circular orbits around a given star always orbit at the same speed at a given distance). These faster-moving planets are orbiting denser stars.
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A fraction of these candidates will likely be ruled out as false positives as time goes on, while the remainder stand to be confirmed as real planets by follow-up analysis. For example, the large orange object in a very close-in orbit was shown to be a <a href="http://arxiv.org/abs/1207.2481">background eclipsing binary blend</a>.
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At the beginning of the animation, the grid of rectangles that briefly appears represents the focal plane array of CCD detectors onboard Kepler.
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The current list of planet candidates can be found <a href="http://archive.stsci.edu/kepler/planet_candidates.html"> here</a>
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Music: 2 Ghosts I, Nine Inch Nails.
Animation rendered with Python / PyLab.
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[ Migrated from <a href="http://www.astro.uvic.ca/~alexhp/new/kepler_worlds.html" target="_blank">original post.</a> ]<br />
<br />Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-18483395239922816002013-02-22T14:45:00.002-08:002013-02-22T14:45:53.505-08:00Kepler 11: A Six-Planet SonataSonification of the transits of the remarkable Kepler 11 planetary system.<br />
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Located roughly 2000 light-years from Earth, the star Kepler 11 has a compact system of six planets, detected by the Kepler space observatory through their transits of their host star.<br />
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<iframe allowfullscreen="" frameborder="0" height="281" mozallowfullscreen="" src="http://player.vimeo.com/video/44945226" webkitallowfullscreen="" width="500"></iframe> <br />
<a href="http://vimeo.com/44945226">Kepler 11: A Six-Planet Sonata</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.<br />
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Here, I've taken each transit seen by the observatory and assigned a pitch and volume to it. The pitch (note) is determined by the planet's distance from its star (closer=higher), and they are drawn from a minor 11 chord. The volume is determined by the size of the planet (larger=louder).<br />
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The near-4:5 mean-motion resonance of the innermost two planets is audible as the notes "beat" against each other.<br />
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A triple-transit (three planets crossing the face of the star at once) in August 2010 is also audible. This event is what is illustrated in the artist's impression of the system used in the cover photo.<br />
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Creative Commons license - 2012 - Alex Harrison Parker, Harvard-Smithsonian Center for Astrophysics.<br />
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[ Migrated from <a href="http://www.astro.uvic.ca/~alexhp/new/kepler_sonata.html" target="_blank">original post.</a> ]Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0tag:blogger.com,1999:blog-3875399461809136780.post-83436368319473741902013-02-13T22:05:00.000-08:002013-02-22T14:56:14.898-08:00The Supernova Sonata<iframe allowfullscreen="" frameborder="0" height="313" mozallowfullscreen="" src="http://player.vimeo.com/video/23927216" webkitallowfullscreen="" width="500"></iframe> <br />
<a href="http://vimeo.com/23927216">Supernova Sonata</a> from <a href="http://vimeo.com/alexhp">Alex Parker</a> on <a href="http://vimeo.com/">Vimeo</a>.<br />
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From April, 2003 until August, 2006, the <a href="http://www.cfht.hawaii.edu/">Canada-France-Hawaii Telescope</a> watched four parts of the sky as often as possible. Armed with the largest digital camera in the known universe, CFHT monitored these four fields for a special type of supernova (called <a href="http://en.wikipedia.org/wiki/Type_Ia_supernova">Type Ia supernovae</a>) which are created by the thermonuclear detonation of one or more <a href="http://en.wikipedia.org/wiki/White_dwarf">white-dwarf stars</a>. These explosions are extremely energetic, and can be seen across vast distances in space.
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These four fields covered roughly 16 times the area of the full Moon on the sky, or roughly 1/10,000 of the entire sky. Even though such a small fraction of the sky was monitored, 241 Type Ia supernovae were seen during the period of observation.
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This video is a compilation of the 241 Type Ia supernovae seen in these fields during the CFHT Legacy Survey. The four Deep Fields are shown in color, and the positions of all the supernova are illustrated as time progresses. The animation is rendered at 15 frames per second, and each frame corresponds to just under a single day (one second in the animation corresponds to roughly two weeks of real time).
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Each supernova is assigned a note to be played; details are below the break.<br />
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<b>Volume = Distance: </b>The volume of the note is determined by the distance to the supernova, with more distant supernova being quieter and fainter.<br />
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<b> Pitch = "Stretch:" </b>The pitch of the note was determined by the supernova's "stretch," a property of how the supernova brightens and fades. Higher stretch values played higher notes. The pitches were drawn from a <a href="http://en.wikipedia.org/wiki/Phrygian_dominant_scale">Phrygian dominant scale</a>.
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<b> Instrument = Mass of Host Galaxy: </b>The instrument the note was played on was determined by the properties of the galaxy which hosted each supernova. Supernovae hosted by massive galaxies are played with a stand-up bass, while supernovae hosted by less massive galaxies are played with a grand piano.
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Note that the brightness of the supernovae as shown in the animation are not to scale. Because they are so distant, even these extremely powerful explosions appear very faint upon reaching us here on Earth.
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Created by Alex H. Parker (University of Victoria) and Melissa L. Graham (University of California Santa Barbara / LCOGT).
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<a href="http://www2.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/community/CFHTLS-SG/docs/cfhtls.html">Source of images (Stephen Gwyn's CFHTLS pages)</a>
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Source of SNe data:
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<a href="http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1104.1443">(Conley et al. 2011)</a> <a href="http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1104.1444">(Sulivan et al. 2011)</a>
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[ Migrated from <a href="http://www.astro.uvic.ca/~alexhp/new/supernova_sonata.html" target="_blank">original post.</a> ]Alex Parkerhttp://www.blogger.com/profile/12796140688317556593noreply@blogger.com0