Myths

Myths and big questions

Ten common ideas about Andromeda, checked against the sources.

How this site works. Every fact is in our own words and linked to its source, beside it. Where good sources disagree, we show each version in a “Sources differ” box.

1. MythAndromeda is just a cloud inside the Milky Way.

   FactV1 showed that Andromeda lies beyond our galaxy, and settled the debate about the spiral nebulae. NASA, V1 Britannica: only in the 1920s did Hubble show conclusively that Andromeda is a separate galaxy. Britannica

2. MythWhen the galaxies meet, stars will smash into each other.

   FactStars are so far apart that they would not hit each other. NASA, 2012

3. MythA collision with Andromeda is certain.

   FactIn 2025 a new study using Hubble and Gaia data found only about a 50-50 chance of the two galaxies colliding in the next 10 billion years. NASA, 2025 Lead author Till Sawala said the two could still go past each other. NASA, 2025

4. MythEarth will be destroyed when Andromeda arrives.

   FactNASA said the Sun would probably be flung into a new part of the galaxy, but Earth and the solar system would not be destroyed. NASA, 2012 NASA points out that a warming Sun will make Earth uninhabitable in roughly a billion years, so Andromeda is the least of our cosmic worries. NASA, 2025

5. MythYou need a big telescope to see Andromeda.

   FactIt is one of the few galaxies you can see with your eyes alone, as a milky blur. Britannica On clear, dark nights it shows faintly as a hazy patch; binoculars or a small telescope reveal its bright core and glow. Royal Observatory, Feb 2026

6. MythAndromeda looks tiny in the sky.

   FactIt is so close that it looks six times as wide as the full Moon in the sky. NASA, M31

7. MythAndromeda is moving away from us, like other galaxies.

   FactAndromeda is getting about 110 km (70 miles) closer to us every second. Royal Observatory That speed was measured with the Doppler effect: Andromeda’s motion towards us squashes the waves of its starlight. NASA, 2012

8. MythHubble’s pictures show every star in Andromeda.

   FactEven 200 million stars is only a fraction of Andromeda’s population. NASA, M31

9. MythAndromeda has always been a quiet galaxy.

   FactNASA says the Milky Way has been relatively placid, but Andromeda has had a more dynamic history, probably including a major merger a few billion years ago. NASA, 2025 In 2018 University of Michigan scientists concluded that Andromeda shredded a massive galaxy, now called M32p, about two billion years ago. U. Michigan, 2018

10. MythAndromeda’s satellites are scattered evenly around it.

    FactMost of Andromeda’s dwarf galaxies lie on our side, between Andromeda and the Milky Way, and better distances show that lopsidedness is real. Sky & Telescope Half of them seem confined to one plane, all orbiting in the same direction. NASA, 2025

Big open questions

The researchers say this needs either a very unusual history, or may hint that our standard picture of the cosmos is missing something. Sky & Telescope

In 2025 a new study using Hubble and Gaia data found only about a 50-50 chance of the two galaxies colliding in the next 10 billion years. NASA, 2025

One researcher, Daniel Weisz, called that “weird”: a total surprise nobody fully understands yet. NASA, 2025