M20与M21
2020年8月6日 Messier 20 and 21 Image Credit & Copyright: Emanuele Petrilli Explanation: The beautiful Trifid Nebula, also known as Messier 20, is easy to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in cosmic contrasts shares this well-composed, nearly 1 degree wide field with ope...