The Andromeda galaxy, one of our nearest intergalactic neighbors, has been captured in higher detail than ever before by NASA’s Swift Satellite space telescope. Swift spent around 24 hours staring at the distant smudge of light, taking 330 separate images totaling 85 gigabytes of data.
Visible in the centre of the image is a brightly glowing bulge, which represents a high concentration of older, cooler stars near the galaxy’s nucleus.
The whole image shows a region of space around 200,000 light years across and 100,000 high, around twice the diameter of the Milky Way.
Out on the spiral arms of the galaxy are the younger, hotter-burning stars, still being fed by the clouds of gas and dust they need to fuel their nuclear fusion.
Andromeda, a hop and a skip away in galactic terms at 2.5 million light years, was the first galaxy to be recognized outside the Milky Way, and the nearest spiral galaxy to our own.
Its discovery transformed our understanding of the universe. Beforehand it was thought that the mere 200 billion or so stars of the Milky Way represented the entire cosmos.
Since Andromeda was confirmed to be a separate entity, itself containing around a trillion stars, the estimate has grown to include more than 100 billion galaxies, each containing tens or hundreds of billions of stars.
The Swift Satellite is surveying various galaxies in our neighborhood – known as the Local Group – in order to learn more about how stars form.
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