Lecture 14 Flashcards
Why do comets and asteroids exist?
Comets and asteroids are a result of left over planetesimals
What are the two classes of junk?
Rocky- asteroids
Icy and metallic- comets
What are asteroids?
-Rocky leftovers of planet formation
-Asteroids have a cratered surface
Where do most asteroids orbit?
Most asteroids are found in the asteroid belt between Mars and Jupiter.
How does Jupiter affect the orbits of some asteroids?
Asteroids that are in orbital resonance with Jupiter experience tugs that form gaps in the asteroid belt.
What is a meteorite?
A space rock that falls through Earth atmosphere
What is a meteor?
The trail of particles left by meteorite that hit the atmosphere.
- they are made of ice, rock or iron
Asteroid impacts
-Small impacts happen daily
-Large impacts can cause mass extinction
What evidence can be found relating meteorite impact to mass extinction?
Beneath layer of iridium (a rare Earth element) is where all the dinosaur fossils are found.
How can meteorites cause extinction?
-Impact
-Dust that reduces the amount of sunlight that can reach the Earth
What are comets?
-Comets are the icy counterparts to asteroids
-Their centre is basically a snowball
-Comets remain in deep freeze in the outer solar system and melt- developing a tail- when they are close enough to the sun
What is the coma of a comet?
The atmosphere produced by it’s heated nucleus
What is the plasma tail of a comet?
Gas that escapes from a comet that is pushed by the solar wind
How is the dust tail of a comet pushed?
Photons
Life of a comet
-Icy planetesimals formed in the region between Jupiter and Neptune
-Gravitational interactions with the Jovian planets perturbed their orbits
1. to the inner solar system where they melted
2. to the outer solar system (Oort cloud) where they went into deep freeze
