We reside in the Milky Way galaxy, and being that we exist inside of it, it’s particularly challenging to snag a glimpse of the Milky Way itself. This makes discerning the Milky Way’s size and shape particularly challenging, and with that in mind, what we think the Milky Way looks like today is nothing more than just an educated guess based on what we can observe.
Astronomers often study twin galaxies to learn more about them, and perhaps unsurprisingly, the same principle applies to the Milky Way. Given the technological hurdles today that prevent scientists from viewing the Milky Way from the outside, the best way to study it is by peering at other galaxies like our own.
A so-called ‘twin’ galaxy doesn’t necessarily mean that it’s a replica, nor does it mean that the two galaxies originated from the same place, but it does mean that two galaxies share many similar traits; enough that studying one can teach us more about the other.
One such example is M32, a galaxy that once looked a lot like the Milky Way, that is, until the Andromeda galaxy collided with it. Intriguingly, Andromeda is poised to crash into the Milky Way in the next few billion years, and so studying the remnants of M32 might tell us more about the Milky Way’s inevitable future.