Photo taken on June 19, 2015 shows the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) at the Xinglong ...

A gap is a localized under-density of stars along the stream, while a spur is an over-density of stars stretching out from the main body of the stream. The Milky Way's galactic halo, a roughly ...

Hidden galaxies offering a glimpse into the past could reveal previously unknown secrets of the universe, challenging current models.