Andromeda Galaxy
M31 · NGC 224
The nearest large galaxy to our own and the most distant thing visible to the naked eye. It is approaching us, set to merge with the Milky Way in roughly 4.5 billion years.
Andromeda is a spiral galaxy in the constellation Andromeda about 2.5 million ly from Earth. It spans roughly 150,000 ly, about 1.5 times the width of our Milky Way. The light reaching us tonight left it about 2.5 million years ago.
Spiral
type · Sb
2.5 million ly
from Earth · measured
152k ly
across
3.4
apparent magnitude
Because its light is 2.5 million ly from home, you are seeing Andromeda as it looked roughly 2.5 million years ago. The photons left before that much of history had passed, and are only now reaching us.
At the centre
Andromeda Central Black Hole (M31*)
A supermassive black hole of 140.0 million ☉.
Notable stars here
Nearest galaxies
TriangulumSpiral700,000 ly
apartMilky WayBarred spiral2.5 million ly
apartSmall Magellanic CloudIrregular2.6 million ly
apartLarge Magellanic CloudIrregular2.6 million ly
apartSculptorStarburst11 million ly
apartCigarStarburst11 million ly
apart
Worlds in the same direction on the sky→apartMilky WayBarred spiral2.5 million ly
apartSmall Magellanic CloudIrregular2.6 million ly
apartLarge Magellanic CloudIrregular2.6 million ly
apartSculptorStarburst11 million ly
apartCigarStarburst11 million ly
apart
Source: structural data (position, morphology, brightness, redshift) from OpenNGC (CC BY-SA). Distance from published measurements.