It must have cleared all other celestial bodies, except its own moons, from its orbit.

Astronomers have identified three ultra-massive galaxies -- nearly as massive as the Milky Way -- already in place within the first billion years after the Big Bang. This surprising discovery was made ...

Using ESO's Very Large Telescope (VLT), an international team of astronomers has inspected an icy protoplanetary disk of a young star known as PDS 453. Results of the new study, published on the ...