“Astronomers
have long known that the brightest part of the Milky Way, the pancake-shaped
disk of stars that houses the sun, is some 120,000 light-years across (Science
News: 8/1/19). Beyond this stellar disk is a disk of gas. A vast halo of
dark matter, presumably full of invisible particles, engulfs both disks and
stretches far beyond them (Science News: 10/25/16). But because the dark
halo emits no light, its diameter is hard to measure.
“Now, Alis Deason, an astrophysicist at Durham University in England, and her colleagues have used nearby galaxies to locate the Milky Way’s edge. The precise diameter is 1.9 million light-years, give or take 0.4 million light-years, the team reports February 21 in a paper posted at arXiv.org.”
—Ken Croswell writing in Science News, March 23, 2020
More at https://www.sciencenews.org/article/astronomers-have-found-edge-milky-way-size
“Now, Alis Deason, an astrophysicist at Durham University in England, and her colleagues have used nearby galaxies to locate the Milky Way’s edge. The precise diameter is 1.9 million light-years, give or take 0.4 million light-years, the team reports February 21 in a paper posted at arXiv.org.”
—Ken Croswell writing in Science News, March 23, 2020
More at https://www.sciencenews.org/article/astronomers-have-found-edge-milky-way-size
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