Triangulum

Joining us is the Andromeda galaxy, a slightly larger twin of the Milky Way, about 2.5 million light years distant, and, slightly farther away, a smaller spiral in the Triangulum constellation called M33.

The Triangulum Galaxy — also known as Messier 33 or NGC 598 — is part of the "Local Group," meaning it is part of the same group of galaxies that the Milky Way belongs to.

In this case the asterism is made up of stars from the constellations Libra, Virgo, Centaurus, and Triangulum Australe.

They used computer simulations to model an entire Milky Way–like galaxy and its neighbors, the Andromeda and Triangulum galaxies.

By then, the smaller Triangulum galaxy may have already collided with either of its two larger neighbors.