M103

open star cluster · in Cassiopeia

8,241 light-years from Earth

The last entry in Messier's catalogue as he published it in 1781: a young cluster of hot stars in Cassiopeia and, by Gaia, the farthest open cluster in his list.

• 8,240 light-years (Gaia) · its stars spread over about 45 light-years
• about 30 million years old · 211 of its stars as Gaia measured them

kind

nebula · star cluster

catalogue

M103 · NGC 581

size

44 light-years across