The Andromeda Galaxy is one of the most magnificent objects in the night sky and undoubtedly the most famous galaxy outside our own Milky Way.

Persistent staring with your naked eyes will reveal it as a surprisingly large hazy patch. Andromeda covers as much of the sky as five full moons put together!

Binoculars will show Andromeda in its entirety along with two of Andromeda's companion galaxies, M32 and M110. Careful observation of the nuclear region with a telescope will reveal faint dust lanes.

M31 was once thought to be a nebula inside our galaxy, but in 1923, astronomer Edwin Hubble showed that it was outside the Milky Way.

And it wasn't the only one! Andromeda opened our eyes to the true scale of the cosmos. M31 is now about 2.9 million light-years away. It is over 150,000 light-years across and has a mass 1.2 trillion times that of our sun.

And it's headed this way! Andromeda will collide with our own galaxy, perhaps five billion years from now. It's larger than the Milky Way too, and will devour us. Or, at least, merge with us.

Andromeda's done that before. The Hubble Space Telescope has shown that the Andromeda Galaxy has a double nucleus, indicating that it probably cannibalized another large galaxy.

Click here to see if this object is visible in your sky tonight.