Andromeda galaxy not bigger than Milky Way after all

The Andromeda galaxy, the one nearest to our own Milky Way, isn’t such a big shot after all.

Astronomers had thought Andromeda was about two to three times the size of the Milky Way, and that our own galaxy would ultimately be overtaken by our bigger neighbor.

But the latest research, published Wednesday, evens the score between the two galaxies.

“By examining the orbits of high-speed stars, we discovered that this galaxy has far less dark matter than previously thought, and only a third of that uncovered in previous observations,” said study lead author Prajwal Kafle of the University of Western Australia.

Both galaxies are about 800 billion times the mass of the sun, the study determined. Since they’re so similar in size, “we can put this gravitational arms race to rest,” said University of Sydney astrophysicist Geraint Lewis.

At about two million light-years apart, the Milky Way and Andromeda are two giant spiral galaxies. Andromeda is so bright and close to us that it is one of only 10 galaxies that can be spotted from Earth with the naked eye, NASA reports.

Still, astronomers think the two galaxies will eventually collide, but it’s not something any of us have to stay up nights worrying about: A collision is still some 4 billion years from now.

According to NASA, although the galaxies will plow into each other, stars inside each galaxy are so far apart that they will not collide with other stars during the encounter. However, the stars will be thrown into different orbits around the new galactic center.

Simulations show that our solar system will probably be tossed much farther from the galactic core than it is today.

The study was published in the journal Monthly Notices of the Royal Astronomical Society.


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