Our own Milky Way galaxy, long considered a “little sister” to the larger Andromeda Galaxy, is all grown-up, according to new research. The findings, presented at a Jan. 5 meeting of the American Astronomical Society in Long Beach, Calif., by Harvard-Smithsonian Center for Astrophysics (CfA) researchers, show that the galaxy has about 50 percent more mass — about the same as Andromeda — and is rotating about 100,000 mph faster than previously thought.

The larger stature has a downside, however. With greater mass, our galaxy exerts greater gravitational pull, which increases the likelihood of collisions with the Andromeda galaxy or smaller nearby galaxies.

Harvard-Smithsonian researchers also presented new findings on star and planet formation at the meeting. New research led by Thayne Currie of the CfA shows that giant planets like Jupiter must form relatively quickly out of the material surrounding a new star because that material is all but exhausted in 5 million years.