Cassiopeia A is the 300-year-old remnant created by the supernova explosion of a massive star. Each Great Observatory image highlights different characteristics of the remnant.
Cassiopeia A is the 300-year-old remnant created by the supernova explosion of a massive star. Each Great Observatory image highlights different characteristics of the remnant.
Humanity has long sought to learn about the Milky Way, our home galaxy.
When three galaxies collide, what happens to the central black holes growing at the cores of each?