Solar eclipses on Pluto 3022136 219031482 2008-06-13T07:19:06Z Kheider 2155897 remove unref [[Image:Pluto solar eclipse .jpg|thumb|400px|The Sun disappears behind Charon's surface during the total solar eclipse on Pluto of 23rd December 2111 (computer simulation)]] [[Image:Charon eclipse shadow.jpg|thumb|right|330px|Charon's shadow projected onto Pluto during a solar eclipse on 1989-02-25. ([[Celestia]])]] '''Eclipses of the Sun on [[Pluto]]''' are caused when one of its three natural satellites – [[Charon (moon)|Charon]], [[Nix (moon)|Nix]] and [[Hydra (moon)|Hydra]] – [[Solar eclipse|passes in front of the]] [[Sun]], blocking its light. An eclipse can occur only when one of the satellites' [[orbital node]]s, the points where their orbits cross Pluto's [[ecliptic]], is lined up with the apparent position of the Sun as seen from Pluto. Since all three of its satellites orbit in the same plane, the times at which this is possible are the same for all three. There are only two points in Pluto's orbit where this can happen. Charon typically presents an [[angular diameter]] of between 3 and 4 [[degree of arc|degrees of arc]] as seen from the surface of Pluto. The Sun appears much smaller, only 40 [[arcsecond]]s to 1 [[arcminute]]. This means that during solar eclipses by Charon, a large proportion of Pluto's surface can experience a total eclipse. There are large uncertainties in the diameters of Nix and Hydra, Pluto's two smaller moons, and as a result their apparent diameters (as seen from Pluto) are also uncertain. However, it is known that Nix's angular diameter is 3-9 minutes, while Hydra's is 2-7 minutes. These are much larger than the Sun's angular diameter, so total solar eclipses are possible with these moons. The period when eclipses were observed on Pluto was between [[February 1985]] and [[October 1990]].<ref name=enc>{{cite book |author=Lucy-Ann Adams McFadden |coauthors=Paul Robert Weissman; Torrence V Johnson |title=Encyclopedia of the Solar System |year=2006 |publisher=Academic Press |url=http://books.google.com/books?id=G7UtYkLQoYoC&pg=PA545&lpg=PA545&dq=mutual+event+pluto&source=web&ots=jDOfb3sWHL&sig=jjLkVTF21FuL-8TiGUT0gy7X5nQ&hl=en |id=ISBN 0120885891 }}</ref> As seen from [[Earth]], Charon also [[astronomical transit|transited]] Pluto every orbit during this period. By measuring the change in brightness during these transit events, astronomers were able to measure the radius of both Pluto and Charon. Nowadays, telescopes, such as the [[Hubble Space Telescope]] have high enough resolution that the radius can be measured directly. The next period of time when solar eclipses can occur on Pluto will begin October 2103, peak in 2110, and end January 2117. During this period, solar eclipses will occur at some point on Pluto every orbit of Charon. The maximum duration of any solar eclipse by Charon as seen from Pluto during this period is about 90 minutes.<ref>{{cite web |date = 1987-Dec-12 11:28 UT |title = Start of Eclipse |publisher = [http://space.jpl.nasa.gov/ JPL Solar System Simulator] |url = http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=901&vbody=999&month=12&day=12&year=1987&hour=11&minute=28&fovmul=1&rfov=5&bfov=30&porbs=1&brite=1 |accessdate = 2008-06-05}} [http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=999&vbody=10&month=12&day=12&year=1987&hour=12&minute=12&rfov=20&fovmul=-1&bfov=50&porbs=1&brite=1 (Pluto as seen from the Sun during mid-eclipse)]</ref><ref>{{cite web |date = 1987-Dec-12 12:57 UT |title = End of Eclipse |publisher = JPL Solar System Simulator |url = http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=901&vbody=999&month=12&day=12&year=1987&hour=12&minute=57&fovmul=1&rfov=5&bfov=30&porbs=1&brite=1 |accessdate = 2008-06-05}}</ref> ==References== {{reflist}} == External links == *[http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=999&vbody=901&month=12&day=22&year=1987&hour=02&minute=00&fovmul=1&rfov=60&bfov=30&porbs=1&brite=1 Pluto eclipsing the Sun through Jupiter as seen from Charon] (1987-Dec-22) [[Category:Solar eclipses]] [[Category:Pluto]] [[fr:Éclipse solaire sur Pluton]]