Andromeda Galaxy Just Got a lot Smaller

Researchers have discovered the Andromeda galaxy, our closest neighbour is roughly the same size as our own Milky Way galaxy. It had been thought that the Andromeda galaxy was 2 to 3 times larger than our own and would eventually engulf us in around 4 billion years.

This new research coming out of the University of Western Australia found that the Andromeda galaxy is on par weight wise with our own. Astrophysicist Dr Prajwal Kafle used a new technique to measure the speed to escape a galaxy. “When a rocket is launched into space, it is thrown out with a speed of 11 kilometres per second to overcome the Earth’s gravitational pull,”

“Our home galaxy, the Milky Way, is over a trillion times heavier than our tiny planet Earth so to escape its gravitational pull we have to launch at a speed of 550 kilometres per second. We used this technique to tie down the mass of Andromeda.”

The results suggest that scientists previously overestimated the amount of dark matter in the Andromeda galaxy. “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,”

With this new size variance, current simulations of our eventual collision will need to be revised. “We had thought there was one biggest galaxy and our own Milky Way was slightly smaller but that scenario has now completely changed. It’s really exciting that we’ve been able to come up with a new method and suddenly 50 years of collective understanding of the local group has been turned on its head.”

University of Sydney astrophysicist Professor Geraint Lewis said it was exciting to be at a time when the data was getting so good.

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