Surprise! Our home galaxy is no pipsqueak, but it isn't nearly as massive as scientists used to think.
Astronomers often refer to the neighboring Andromeda galaxy, which is around 2.6 million light-years away from us, as the "twin galaxy" of our own Milky Way. But a new study indicates that the two galaxies are quite different when it comes to mass. The research, from an international team of scientists, shows that the Milky Way is about half as massive as Andromeda.
The supermassive black hole is 40 million times as massive as the sun and powers a quasar that existed 700 million years after the Big Bang.
The asteroid zoomed by Earth at a perfectly safe distance of around 1.8 million miles (2.9 kilometers).
Images show surprise changes to the spacecraft as it interacted with the atmosphere.
