M21

open star cluster · in Sagittarius

3,920 light-years from Earth

One of the youngest clusters in Messier's list: its stars formed only 5 to 13 million years ago. On our sky it lies just beside the Trifid Nebula, and at about the same distance, but it sits outside the nebula's glowing gas.

• 3,920 light-years (Gaia) · its stars spread over about 24 light-years
• about 5 to 13 million years old · 212 of its stars as Gaia measured them

kind

nebula · star cluster

catalogue

M21 · NGC 6531

size

25 light-years across