PHYS 183 #10 Asteroids, Comets, and Dwarf Planets

Planetesimals

asteroids, comets, and dwarf planets

why are planetesimals unimportant

only make up 0.0001 mass combined

Why are planetesimals interesting?

• relevant to collisions, geological events

• clues of formation of solar system

Asteroids

• chunk of mostly rock

• orbit sun

• mostly found in asteroid belt

• move differently to planets and stars

Location of comets

• live in outer regions of solar system, Oort cloud

• occasional visitors to inner solar system

composition of comet

• head:

  • center is solid nucleus of dirty ice

  • water methane ammonia, co2

• tail:

  • ion tail pointing away from sun

  • dust tail of carbon and silicone particles

Oort Cloud

• circular cloud of icy asteroids and comets orbiting in different directions

• not just on plane of solar system: circular cloud

Meteor Showers

• remains of comets that create showers of small meteors

  • “shooting stars”

• enter earths atmosphere and burn up