M101 - Pinwheel Galaxy sits over 20 million light years away in the constellation Ursa Major. The galaxy contains lots of hydrogen emitting regions (shown in red), in order to show this separate exposures have to be taken with a Hydrogen alpha filter and then blended with the red and blue data before combining to create a colour image. The total exposure time is over 18 hours taken over a two month period

GordonHaynes just now Via Flipboard