“Why they are so incredibly massive isn’t known, but astronomers are pretty sure their development is linked to their presence at the center of their galaxy. There are so many stars and so much gas and dust that the black hole can grow large very quickly. And since many galaxies collide repeatedly during their long lifetimes, supermassive black holes have a ready-made way to collide and coalesce into even heavier supermassive black holes.”
But what about black holes that are even larger or so small that they may not even exist?
Sagittarius A*, the Milky Way’s supermassive black hole, appears at the 6-minute mark. Messier 87‘s black hole, Pōwehi—the first black hole we imaged—appears just after 8m20s. A behind-the-scenes explainer (and black hole merch ad) begins at 11m25s.
Watch these related videos next:
• Sagittarius A*, the supermassive black hole at the center of the Milky Way
• The first image of a black hole: A three minute guide
• Taking the very first picture of a black hole – Black Hole Hunters
• Stephen Hawking explains black holes in 90 seconds
• Planet and star size comparisons from smaller to larger
• What is the largest known star in the universe?