All Galaxies Have One Surprising Trait in Common, Study Finds

Galaxies are the suburbs of the universe. While they’re all very different from each other, scientists have realized they’re astonishingly the same in one peculiar aspect: the time they move.

A team of researchers at the International Center for Radio Astronomy Research (ICRAR) has found that all galaxies, regardless of size, move once every billion years. The group came to this conclusion by doing various calculations based on the average interior density of galaxies, since this number is the same for galaxies of the same size. Their findings have been published in the Monthly Notices of the Royal Astronomical Society.

“It’s not Swiss watch precision,” the study’s lead author Gerhardt Meurer says in a statement. “But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way around.”

Pinwheel galaxy


Meurer and his team used previously existing models of various galaxies to assist with their calculations. Oddly enough, they found older stars at the edges of galaxies. They had expected to find a scattering of younger stars in these distant regions.

“This is an important result because knowing where a galaxy ends means we astronomers can limit our observations and not waste time, effort and computer processing power on studying data from beyond that point,” Meurer says. “So because of this work, we now know that galaxies rotate once every billion years, with a sharp edge that’s populated with a mixture of interstellar gas, with both old and young stars.”

It’s pretty mind-blowing — perhaps existential crisis-inducing — to think about galaxies moving with along with some sort of universal rhythm, no matter how big. Just something small to ponder on your way home from work.

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