Changes
Vega
,/* The Star */
Vega rotates so fast that it only takes some 12.5 hours to complete one rotation, in comparison the Sun which takes 25.4 days to complete one rotation. This rotation is so fast that observations suggest that the star is rotating at some 91 percent of the angular velocity needed to cause the star to physically fly apart. Vega is thus 23 percent wider along its equator than at its poles, as well as some 2300K cooler<ref>http://www.noao.edu/outreach/press/pr06/pr0603.html</ref>. Here on Earth, Vega is seen as pole on (looking directly at its pole).
Vega, like many young stars, is orbited by a disk of fine dust and ice, first discovered in 1998. In 2005, using the Spitzer Space Telescope, NASA astronomers observed that the disk was actually far larger then originally thought, and extends outwards from 70–102 AU to as much as 850 AU. Because the circumstellar disk of dust around Vega is partially gathered into larger clumps, some astronomers believe this is caused by the gravity of a giant planet in orbit<ref>http://www.space.com/scienceastronomy/astronomy/dusty_worlds_020123-1.html</ref>. However, so far no substellar companions of Vega have been confirmed. In 2006, the CHARA array at Mt. Wilson observed a second inner disk of dust within 8 AU of the star<ref>http://adsabs.harvard.edu/abs/2006A&A...452..237A</ref>.
Vega's [[habitable zone]], where liquid water could exist on the surface of an [[Earth|Earth-like]] world, is centered on 7.1 AU, a distance between the orbit of [[Jupiter]] and [[Saturn]].
