Ch 29 Flashcards
Retrograde motion
When a planet moves in the opposite direction across the sky
Astronomical unit
Unit used for measuring average distance from the Sun. What could it be? It is the average distance between Earth and the Sun.
Perihelion
When a planet is closest to the Sun in its orbit it is at this
Aphelion
When a planet is at the farthest point from the Sun in its orbit
Eccentricity
The ratio of the distance between the foci to the length of the major axis. Shape of a planets elliptical orbit is defined by this
Terrestrial planets
The inner four planets are these, which are close to the size of Earth and have rock solid surfaces 😄
Gas giant planets
The farthest four planets are these, which are much larger than the terrestrial planets, more gaseous, and have a slight de-abundance of a surface that is not gas
Precession
The wobble in Earth’s rotational axis
Liquid metallic hydrogen
A form of hydrogen that has properties of a liquid and that of a metal. Can only exist under VERY high pressure.
Belt
Low, warm, dark colored clouds that sink
Zone
High, cool, light colored clouds that rise
Planetesimal
Solid bodies formed by solid particles colliding and sticking together. Can reach hundreds of kilometers in diameter. Growth of these continued by collisions and stuff, but only some survived and turned into planets
Asteroid
Leftovers from the formation of solar system. Goes from a few kilometers in diameter to about 1000 km!
Meteoroid
When any interplanetary material or pieces of asteroid enters Earth’s atmosphere, it’s called this
Meteor
The streak of light produced when a meteoroid falls towards the Earth
