Milky Way Is Twice the Size We Thought

Peter writes to tell us about a research group at the University of Sydney in Australia, who in the middle of some calculation wanted to check the numbers everybody uses for the thickness of our galaxy at the core. Using data available freely on the Internet and analyzing it in a spreadsheet, they discovered in a matter of hours that the Milky Way is 12,000 light years thick, vs. the 6,000 that had been the consensus number for some time.

Comments

Re:Is this real information?

[Siener]

How hard is it to map the galaxy? If we don't know where the stars are, we can't know the size. If we know, we don't need it; we can describe the actual, real, shape.

It's pretty hard to measure the size and shape of the Milky Way simply because we are stuck in the middle of it. Measuring the size and shape of far away galaxies is a lot easier because we have a better view. Our galaxy is a flat disk with spiral arms where we are in one of those arms - the overall structure is very hard to measure from that perspective. To complicate things further there is quite a lot if interstellar dust that messes up our view in certain directions.

As an analogy - imagine being stuck in a traffic jam. Figuring out the extent of it is very hard from the view you get from your car. A helicopter in the sky has no problems though.