Sagittarius A* is the supermassive black hole at the center of our home Milky Way galaxy. It has a mass equal to billions of suns and has an accretion disk made up of gas and dust surrounding it.

Shapley determined that the Milky Way was 300,000 light years across ... his discovery because he had access to this state-of-the-art technology.” The Hooker telescope was the brainchild ...

In 1610, astronomer Galileo Galilei used the newly invented telescope to show that the Milky Way was composed of a huge number of faint stars. For the next 300 years, astronomers assumed that the ...