Galaxies are gigantic, sometimes hundreds of thousands of light-years across and the Milky Way is no exception. Still, a recent study has sought to reanalyze the width of our galactic home and researchers have discovered it might actually be much smaller than we thought.
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00:04 Galaxies are gigantic, sometimes hundreds of thousands of light years across.
00:08 And the one we live in, the Milky Way, is no exception.
00:11 Still, a recent study has sought to reanalyze the mass of our galactic home.
00:15 And researchers have discovered it might actually be much smaller than we thought.
00:18 A big problem with measuring the size of the Milky Way is that we're in it.
00:22 In the center of the whole thing is a large mass of dust and gas surrounding a black hole.
00:26 That means we'll never be able to see the other side of the galaxy,
00:29 or many of the stars which reside there, which is another way to figure out the size of a galaxy.
00:33 Astronomers can compare the speed of orbiting stars to their distance from the galactic center.
00:37 But having both an obfuscated center and an impossible-to-see far side of the galaxy makes that hard.
00:42 Which is why this new study used data from the Gaia spacecraft,
00:45 one which has pinpointed 1.8 billion stars and calculated the speed and rotations of some 1.5 billion of them.
00:52 This gave researchers a much larger number of stars to calculate our galaxy's rotation curve,
00:57 finding that the mass of the Milky Way galaxy is now estimated to only be 200 billion solar masses,
01:02 or only 20% of previous calculations.
01:05 Even the upper limit of the new estimate puts it at 540 billion solar masses,
01:09 or less than half the mass of what astronomers previously believed.
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