Super Black Holes Hold Galaxies Together

Wednesday’s “Astronomy Picture of the Day” from NASA:


From an article linked under that picture:

Like discovering a neighborhood house assumed to be vacant is actually inhabited, over the past decade researchers realized that most galaxies have at least one black hole in residence in their central regions. But these black holes aren’t the stellar variety with three to ten times the mass of our Sun. Their size swamps the imagination- they have millions, sometimes billions, of solar masses. Even our home galaxy, the Milky Way, has a four million solar mass black hole located at its center, about 27,000 light years from Earth. Galactically speaking, that places it in our own backyard! Well, there goes the neighborhood! 

I love these recent discoveries that turn our knowledge of the universe on its head!