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M81 - A Grand Design Spiral
Arguably one of the most beautiful spiral galaxies in the sky, M 81
represents the 'Grand Design' spiral galaxies. Such grand design spirals
show long and well formed spiral arms. In this
image, the light of hot hydrogen gas produces reddish-purple
clouds.
Those
represent "HII Regions" where star formation has produced massive hot stars
that cause the surrounding hydrogen to glow.
M81 lies between the bowl of the Big Dipper and the North Star; despite being
over 12 million light years from us, it is easily visible in binoculars on a
dark, moonless night as a faint smudge of light. It lies near another bright
galaxy, M82 - and in fact in the distant past M81 and M82 passed quite close
together. One result of the near miss is the enhancement of M81's beautiful
spiral arms.
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