<a href="//commons.wikimedia.org/wiki/NASA" title="NASA">NASA</a>'s <a href="//commons.wikimedia.org/wiki/Category:Swift_Gamma-Ray_Burst_Mission" title="Category:Swift Gamma-Ray Burst Mission">Swift</a> satellite has acquired the highest-resolution view of the neighbouring spiral galaxy M31. Also known as the Andromeda Galaxy, M31 is the largest and closest such galaxy to our own. It's more than 220,000 <a href="https://en.wikipedia.org/wiki/light-year" class="extiw" title="en:light-year">light-years</a> across and lies 2.5 million light-years away in the <a href="//commons.wikimedia.org/wiki/Category:Andromeda_(constellation)" title="Category:Andromeda (constellation)">constellation Andromeda</a>. Dense clusters of hot, young, blue <a href="//commons.wikimedia.org/wiki/Star" title="Star">stars</a> sparkle in the disk beyond the galaxy's smooth, redder central bulge. Star clusters are especially plentiful along a ring about 150,000 light-years across.
NASA
2009-09-18
<a rel="nofollow" class="external text" href="http://svs.gsfc.nasa.gov/vis/a010000/a010400/a010485/index.html">NASA Goddard Space Flight Center</a>