Pluto In Passing - Random Trivia Answers

• A1) Neptune. The gas giant was also the outermost planet for most of the last thirty years, as Pluto swung inside it between 1979 and 1999.
• A2) Mercury. The innermost planet is now the only one smaller than Ganymede and Titan. Pluto is also smaller than Callisto, Io, our moon, Europa, and Triton.
• A3) Mars. With an eccentricity of 0.206, the red planet is now the oddest by quite a bit (Mercury is less than half as eccentric at 0.093).
• A4) Eris. Formerly known as 2003 UB₃₁₃ and nicknamed Xena (and Lila). With a radius about thirty miles greater than Pluto's, Eris, named for the Greek goddess of chaos and strife, probably sealed Pluto's fate. Eris's moon, unofficially dubbed Gabrielle, is now called Dysnomia (Eris's daughter, the spirit of lawlessness).
• A5) Ceres. The largest asteroid was originally considered to be a planet, but after several other relatively large asteroids were discovered it was downgraded. Although Ceres was upgraded to the status of dwarf planet, the next two largest asteroids, Vesta and Pallas, were not. Many more trans-Neptunian objects may join the list of dwarf planets in the future, so while you're mourning Pluto, be thankful that you don't have to learn the names of a hundred planets.
• A6) Pluto and Charon. Another major factor in Pluto's demotion is the fact that Pluto and Charon revolve around a center of mass that lies in the space between them (and not inside Pluto).
• A7) Claude Tombaugh. The astronomer found the white speck on photographic plates on February 18, 1930.
• A8) Percival Lowell. Tombaugh worked at the Lowell Observatory in Flagstaff, Arizona, which had been founded in 1894 by its namesake to search for "Planet X".
• A9) Three. Nix and Hydra were discovered through the Hubble Telescope on May 15, 2005 and officially joined Charon on June 21, 2006.
• A10) Nitrogen. Methane and carbon monoxide are also present in significant quantities.
• A11) 248 years. George Washington married Martha Dandridge Custis, the French and Indian War was near its midpoint, and Voltaire's Candide was published in 1759, one revolution ago for Pluto.
• A12) 6 days (and 9 hours and 17 minutes and 36 seconds). Pluto and Charon are tidally locked, with the sames sides permanently facing each other, so this is also the length of Charon's revolution around Pluto.