“Mashup!” –Massive Ancient Collision ‘Puffed and Fractured’ the Milky Way

  “While there have been many dwarf satellites falling onto the Milky Way over its life, this was the largest of them all,” said Sergey Koposov of Carnegie Mellon University, about the collision 10 billion years ago with the massive Gaia Sausage satellite galaxy, whose total mass in gas, stars and dark matter was more … Continue reading “Mashup!” –Massive Ancient Collision ‘Puffed and Fractured’ the Milky Way