In 2005 astronomers found a dense grouping of stars in the Virgo constellation. It looked like a star cluster, except further surveys showed that some of the stars are moving towards us, and some are moving away. That finding was unexpected and suggested the Stream was no simple star cluster. A 2019 study showed that … Continue reading Astronomers Find the Hollowed-Out Shell of a Dwarf Galaxy that Collided With the Milky Way Billions of Years Ago