11 Andromeda Galaxy Facts

When we’re looking up at the night sky, there are many different things stars and constellations for us to look at. However, one of the most interesting things we can see from our planet is the Andromeda galaxy. Like the Sombrero galaxy, it is filled with globular clusters and a fairly small black hole.

Aside from our own galaxy the Milky Way, Andromeda is probably the one that everybody knows, which makes sense as we’re pretty close to one another. Let’s look at some facts about the Andromeda galaxy.

  1. The estimated distance between our galaxy and the Andromeda galaxy is estimated to be 2.5 million light years.
  2. The Andromeda galaxy is in the same group of galaxies as the galaxy we are in, the Milky Way. It is the largest galaxy in this group of more than 30 others.
  3. It is more than double the size of our Milky Way, too. The Andromeda galaxy has a radius of 110,000 light years, whereas the Milky Way’s radius is approximately 52,800 light years.
  4. Although it is double the size of our galaxy, it has around the same amount of mass as the Milky Way.
  5. The reason that Andromeda galaxy is named as such is that it is in the Andromeda constellation. This takes its name from the beautiful Princess in Greek mythology that was saved from certain death by Perseus.
  6. In approximately 4.5 billion years time, the Andromeda galaxy will collide into the Milky Way. They’ll then form together to create an even bigger galaxy.
  7. The Andromeda galaxy has many different smaller satellite galaxies which are bound to it by gravity. The largest of these is the M110 dwarf galaxy.
  8. When we’re looking at the night sky without a telescope, the Andromeda galaxy is the only thing that we can see that isn’t part of our own galaxy.
  9. What’s interesting about Andromeda is that we actually have writings from over a thousand years ago that note down its appearance in the night sky. This is from Persian astronomer Abd al-rahman al-Sufi’s The Book of Fixed Stars.
  10. It’s estimated that the Andromeda galaxy is around 10 billion years old. It’s made up of several other galaxies collided and merging together.
  11. There are many different globular clusters within the galaxy. Astronomers currently have more than 460 different clusters noted down and associated with Andromeda.
  12. The most famous of these globular clusters, Globular One (officially named Mayall II), is the largest of any in our Local Group of galaxies.


No one knows for sure the amount of stars that are in the Andromeda galaxy. However, we think that there are around half a trillion stars within our own galaxy, the Milky Way. So, astronomers generally think that there are more than a trillion stars in the Andromeda galaxy, seeing that it’s double the size.

Assuming you’re in the Northern hemisphere, the best time to see the Andromeda galaxy is usually around August/September time. It is quite easy to find the galaxy because the whole Andromeda constellation is usually quite bright during this time.

Honestly, asking this question to different astronomers will get you many different answers. Many of them think that there must be life in the Andromeda galaxy. There’s a trillion stars there, meaning there are potentially a trillion suns there with some of these having planets orbiting them. With this many potential planets, surely one of these must have harboured life? Well, you’d think so. However at the opposite end of the spectrum, there is no certainty of life in the other planets in our solar system. So, maybe Earth is just a rare anomaly out of billions and trillions of other planets out there – no one knows.

Before we knew about galaxies and they were defined by Edwin Hubble, we used to refer to the Andromeda galaxy as the Andromeda Nebula. However, using Hubble’s classifications of different galaxies, we can now say that it is a barred spiral galaxy.

Honestly, it’s not even worth thinking about because the distance is so mind-bogglingly large. Remember, we’re more than 2.5 million light years away from Andromeda. So, it would take us 2.5 million years if we could travel at the speed of light. The fastest unattended spacecraft we’ve launched has gone at around 250,000mph, so by this calculation it would still take around 50 trillion hours for it to reach the Andromeda galaxy – that’s assuming there’s no bumps on the way!

These are just some of the facts about the Andromeda galaxy. We actually know a surprising amount about it, and much of what we think we know about our own galaxy is based off assumptions we can see in Andromeda. Hopefully you’ve learned a new fact about this galaxy!

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