Andromeda
On a dark night you can see another galaxy with just your eyes: Andromeda, whose light left it about 2.5 million years ago.
What’s going on
Andromeda is the nearest large galaxy, a spiral like ours with perhaps a trillion stars. To the eye it is a faint oval smudge, easiest to find from the Northern Hemisphere on autumn evenings. About a century ago, Edwin Hubble showed it lies far outside the Milky Way, which revealed that the universe is full of galaxies. The light you see set out long before modern humans existed.
Myth
The Milky Way is certain to crash into Andromeda in about 5 billion years.
Fact
A 2025 study puts a merger within the next 10 billion years at about 50–50.
Learn more
NASA Science, “NASA’s Hubble Traces Hidden History of Andromeda Galaxy” (2025); T. Sawala et al., “No certainty of a Milky Way–Andromeda collision”, Nature Astronomy (2025).
Look up tonight
From the Northern Hemisphere, look on autumn evenings from a dark place. Andromeda is a faint oval smudge, easiest to see if you look slightly to one side of it.
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