Galaxies, Part 2: Crash Course 39

What type of galaxy is the Milky Way?

• Irregular

• Spiral

What was peculiar about the object 3C273 discovered in the 1960s?

• It was moving at the speed of light.

• It emitted an unusual amount of radio radiation.

What powers active galaxies?

• Collisions with other galaxies

• Supermassive black holes

What is the name given to the most luminous objects in the universe, powered by supermassive black holes?

• Pulsars

• Quasars

What forms around a black hole, heating up material to millions of degrees?

• An accretion disk

• A globular cluster

What will eventually happen between the Milky Way and the Andromeda galaxy?

• They will collide and merge.

• They will destroy each other.

What is the estimated number of galaxies in the Universe?

• About a hundred billion

• About a million

What kind of light do X-ray observatories detect from active galaxies?

• X-rays

• Ultraviolet light

What is the fate of material that falls into a black hole's accretion disk?

• It is ejected back into space.

• It heats up and emits light.

What larger structure is the Local Group a part of?

• The Andromeda Supercluster

• The Laniakea Supercluster