M101

Constellation: Ursa Major

Distance: 23.5 million light-years

M101 is a one of the largest known disc galaxies. It measures 170,000 light-years in diameter, 70% larger than our Milky Way, although the masses of these 2 galaxies are similar. It is viewed face-on, allowing us to see its grand spiral structure. Abundant large star forming H-II regions populate its spiral arms, (seen as red). Brilliant, young clusters of hot blue newborn stars fill out the spiral arms.