Facts about Galaxies
- 07
Lenticular galaxies, which possess a central disk with a prominent bulge but lack spiral arms, make up roughly 20 percent of galaxies in the nearby universe and may form when galactic collisions strip away a spiral galaxy's rotating disk.
- 06
Elliptical galaxies like M87 contain mostly old stars and lack the rotating disk structure of spiral galaxies, suggesting they formed through ancient collisions between smaller galaxies billions of years ago.
- 05
Ultra-bright quasars powered by supermassive black holes can outshine entire galaxies containing billions of stars, reaching luminosities of 100 trillion suns across billions of light-years.
- 04
Spiral galaxies like NGC 1232 rotate so quickly at their edges that stars should fly apart, yet observations suggest dark matter's gravity holds them together.
- 03
Our Milky Way galaxy spans approximately 100,000 light-years in diameter and rotates so slowly that one complete rotation takes roughly 230 million years.
- 02
At 55 million light-years away, Messier 87 harbors a supermassive black hole with a mass equivalent to 6.5 billion suns, directly imaged by the Event Horizon Telescope in 2019.
- 01
The Andromeda Galaxy contains roughly one trillion stars and will collide with the Milky Way in approximately 4.5 billion years.