NASA recently released images of the Andromeda galaxy, an "enticing empire of stars" that can be seen with the naked eye if weather conditions are just right. About 100 years after astronomer ...

Sgr A*, in turn, is dwarfed by some supermassive black holes detected in other large galaxies such as one with a mass 6.5 billion times greater than that of the sun in a galaxy called Messier 87. That ...