Big or Small, All Galaxies Spin Like Clockwork Once Every Billion Years

Wednesday, 14 March 2018 - 10:34AM
Wednesday, 14 March 2018 - 10:34AM
Big or Small, All Galaxies Spin Like Clockwork Once Every Billion Years
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Image credit: NASA

We're all constantly spinning.

From the atoms that make up out DNA to the planet we live on, to even out galaxy itself and all the stars within, everything is in a constant state of orbital rotation, as we spin endlessly around the biggest, heaviest sphere of influence in our respective circles.

Some of these rotations take longer than others. While the electrons in an atom whiz around in a circle so fast that they're hard to measure, the Earth takes 24 hours to complete a rotation, and just a little over 365 days to make it all the way around the sun.

The Milky Way galaxy, as it turns out, takes a little longer to complete a rotation; a billion times more than the Earth in its journey around the sun, to be exact.

The Milky Way is a decently sized galaxy, so logically, a smaller galaxy should take less time, and a bigger galaxy should take longer, right?

Wrong. According to new research published in Monthly Notices of the Royal Astronomical Society, all galaxies, regardless of size, take approximately the same amount of time to complete one full rotation. Physics is nutty sometimes.

Obviously, this isn't literally 1 billion years—the rules of the universe aren't so strange as to enjoy that kind of symmetry—but there does seem to be a prevailing regular time that a rotation takes to occur.

According to Professor Gerhardt Meurer from the UWA node of the International Centre for Radio Astronomy Research:

Opening quote
"It's not Swiss watch precision, 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 round. Discovering such regularity in galaxies really helps us to better understand the mechanics that make them tick—you won't find a dense galaxy rotating quickly, while another with the same size but lower density is rotating more slowly."
Closing quote


This in and of itself is mind-boggling, because it means that bigger galaxies must logically be spinning a lot faster than smaller ones in order to make a rotation so quickly. As with other objects that rotate on a much smaller scale, the science here is almost too painful to think too hard about.


Di

Assscovering such regularity in galaxies really helps us to better understand the mechanics that make them tick-you won't find a dense galaxy rotating quickly, while another with the same size but lower density is rotating more slowly

Read more at: https://phys.org/news/2018-03-astronomers-galaxies-clockwork.html#jCp


As if things weren't complicated enough, scientists also found an unexpected "sharp edge" around galaxies. Where the furthest outreaches of a galaxy's outer rim should be, according to our previous understanding, completely bereft of old stars, this new research found both old and new stars mixed in together right at the tips of various galaxies.

This suggests that our current understanding of how galaxies age may be incomplete. It'll take a lot more research to figure out exactly what's going on here, but it's kind of fun to know that all galaxies throughout the universe (or, at least, the ones we've been able to get a good look at) all behave according to the same rotation time.

Centuries ago, a Christian clergyman by the name of William Paley noted the similarities between the complexity of the universe and the precision engineering of a pocket watch. It turns out he was even more correct than he realized; the universe has been keeping time for eons without any of us noticing.
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