Vega

Vega is a bright blue star 25 light years away. Vega is the brightest star in the Summer Triangle, a group of stars easily visible summer evenings in the northern hemisphere. It's companions are Deneb and Altair. Vega is also known as Alpha Lyrae. Vega 是一颗25光年外的明亮蓝星。Vega 是夏季三角形中亮度最高的星，夏季夜晚在北半球很容易看到。它的伴星是Deneb和Altair。Vega 也被称为Lyrae座的α星。

"14,000 years ago, Vega, not Polaris, was the north star. Vega is the fifth brightest star in the night sky, and has a diameter almost three times that of our Sun." (NASA) It is 60 times brighter than the Sun, and is projected to have a lifetime of about 350 million years, or 1/13 the lifetiime of the Sun.

Images made by the Spitzer Space Telescope give details about the large dust cloud surrounding Vega. This massive amount of debris is thought to be the result of a collision of perhaps Pluto sized objects. This dust is being blown away by the intense light of the star, so the collision is likely to have occurred within the last million years. The massive dust disk extends to at least 815 astronomical units, or about 20 times the size of our solar system.

Sources

• http://antwrp.gsfc.nasa.gov/apod/ap980823.html
• http://www.jpl.nasa.gov/news/news.cfm?release=2005-007
• http://www.spitzer.caltech.edu.