New Research Says the Milky Way Is Far Bigger Than We Thought Possible
If NASA can spot a tiny exoplanet millions of miles away just by catching the momentary dip in brightness as it passes in front of a star, you'd think that astronomers would have a pretty good handle on how big our own Milky Way galaxy is.
It turns out that's not the case—originally, the Milky Way was estimated to be around 100,000 light years across, but a team from Rensselaer Polytechnic Institute announced in 2015 that it was actually 50% larger than that.
Now, recent research from the Canary Islands Institute of Astrophysics and the National Astronomical Observatories of Beijing has revised that number again— they say the Milky Way's diameter should technically be between 170,000 and 200,000 light-years in length, almost 100 percent larger than our original estimates.
The new number comes from research conducted on far-flung stars that are still on our galactic plane but haven't been counted as part of the Milky Way's official disk.
According to the new study, these stars actually have similar compositions to those within the disk proper, meaning that they should technically be considered part of our galaxy.
In effect, this redraws the boundaries of our galaxy, but doesn't signal a major change in its content—according to Martin Lopez-Corredoira, one of the researchers associated with the study:
"Although we have increased the size of the galactic stellar disk, the number of stars and the total mass of the galaxy [are] not significantly affected because the outermost disk...has a very low density of stars."
This means that the Milky Way hasn't suddenly jumped up a few weight classes when it comes to its inevitable bout with the Andromeda Galaxy, which will collide with us in a few billion years.
Hopefully, we'll have a definitive answer of just how large our home galaxy is by then.