Our Part of the Milky Way Is Four Times Bigger Than We Thought

Our Part of the Milky Way Is Four Times Bigger Than We Thought

Published in the journal Science Advances this week, a new study reported that our surrounding area of stars, gas, and dust—called the Local Arm, Orion Spur, or Orion–Cygnus Arm—is actually about 20,000 light-years long. The immediate implications are that the galaxy is actually a little more symmetrical and regular than scientists previously thought, says one of the study's co-authors, Mark J. Reid of the Harvard-Smithsonian Center for Astrophysics. Although a better understanding of our galaxy's structure doesn't necessarily mean gravity or other forces acting on us are different from what we expect, it could help us better understand large-scale features in the future, notes Reid. The Local Arm is still considerably shorter than the Milky Way’s four main arms, which wind around the galaxy's center for roughly 80,000 light-years. The total diameter of the galaxy is often reported as about 100,000 light-years, although Reid says more recent evidence suggests it is probably more like 70,000 light-years, at least to the edge of where star density starts to really drop off.

Read More: Nat Geo

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