Astronomy Flashcards
What is retrograde motion?
It is when the planets appear to occasionally move backwards in the sky.
What is the geocentric model?
The geocentric model is based on the theory that the earth is the center of our solar system and celestial bodies orbit around it. Aristotle theorized this.
What is the heliocentric model?
The heliocentric model is based on the theory that the sun is the center of our solar system and celestial bodies orbit around it. It was Nicolas Copernicus who proposed this because he was troubled by retrograde motion.
Define “epicycle”.
An epicycle is a mini orbit that comes off a planet’s main orbits. This is an additional level of circular motion which Ptolemy theorized.
What is an Oort Cloud?
An Oort cloud is a spherical cloud of frozen objects at the very edge of our solar system.
What is a meteorite?
They are meteors that entered our atmosphere and burned up.
What are meteors and how do you know they are meteors?
A meteor is made up of thousands of dust and rock fragments. They come from passing tails of comets.
You know they are meteors if they orbit around the sun and planets.
What is a comet?
They are “dirty snowballs” and they orbit in the Oort cloud.
What is an asteroid and how do you know they are asteroids?
Asteroids are minor planets. They are made of carbonaceous/silicate.
You know they are meteors if they orbit between Mars and Jupiter or cycle around the sun.
