标签： 红巨星

2022年2月24日 Beautiful Albireo AB Image Credit & Copyright: Robert Eder Explanation: Beta Cygni is a single bright star to the naked eye. About 420 light-years away it marks the foot of the Northern Cross, famous asterism in the constellation Cygnus. But a view through the eyepiece of a small telescope will transform it into a beautiful double star, a tre...