From Mara Johnson-Groh at Astronomy:
Despite residing in it, it’s hard for us to know exactly how big the Milky Way is. But new research has found that our galaxy is bigger than previously thought. Using a large survey of stars instead of just models (as previous researchers did), astronomers have now determined the disk of our galaxy to be 200,000 light-years across — twice as large as was believed a decade ago.
With a process known as spectroscopy, researchers from the Instituto de Astrofísica de Canarias and at the National Astronomical Observatories of Beijing studied the chemical composition of over 4,600 stars from two surveys, APOGEE and LAMOST, and mapped out which stars are part of the disk and which belong to the halo. The results, published May 7 in the journal Astronomy and Astrophysics, clearly show disk stars much farther from center of the galaxy than before. More.
Assuming that the distant stars taper off exponentially, they estimate that the Milky Way is only somewhat smaller than the Andromeda nebula at 220 000 light-years across.
Well, maybe there are more places for which we can theorize about and look for life. Adjusted measurements of size don’t pose the same problem as adjusted measurements of time do (See Globular Clusters story) because the time proposed from the Big Bang – 13 billion or so years – imposes a constraint on the events that can take place via proposed mechanisms. It does, however, flood the market for splintered lecterns. 😉
Also, those who make an issue of the “insignificance” of our galaxy may want to take note.
Note: We liked Johnson-Groh’s title, “Supersize me,” but did not steal it. ”
See also: Experimental physicist Rob Sheldon takes issue with News’s globular clusters story Sheldon: A physics model is always incomplete. Some missing piece of trivia will turn out to be important. So always take models, even elaborate expensive super-computer models, with many grains of salt. They are only as good as the assumptions that go into them.
Are globular clusters 4 billion years younger than previously thought? It “brings into question” more than the mechanics of galaxy formation. There is considerable distance between nine billion years and thirteen billion years. An equivalent claim for life on Earth would shave a billion years off the development of life. If it’s true, it’s true. But the finding doesn’t fill onlookers with confidence about the accuracy of dating systems.