Earth in Space Flashcards
Apparent Motion
The motion that appears to be happening based on what we’re seeing with our eyes. This motion is not necessarily real. Optical illusion.
For example, when you’re in a car driving past trees, they seem to be moving past the window, but in reality, they’re completely stationary.
Model
A program, image, or data set used to explain a system or predict the habits of a system.
Actual Motion
The realistic motion of an object, regardless of what it appears to be.
For example, when you’re in a car moving past trees, the trees APPEAR to be moving, but the ACTUAL motion is that of the car speeding past the trees.
Geocentric Model
The model used anciently to describe our solar system. This model puts Earth at the center of our solar system and the sun, planets, and stars as objects circling around it.
Heliocentric Model
The model that replaced the geocentric model. This model places the Sun at the center of the solar system, with the planets moving around it.
This model also accounts for the movement of stars; later it was added that stars we could see were in other solar systems and did not revolve around our own sun. But this model can account for that.
True or False: Gravity exists between all objects in the universe.
True
What are the two factors that determine how strong the gravitational pull is between two objects?
- Mass
- Distance between the centers of the two things
How old is the earth?
4.543 billion years
How old is the Milky Way galaxy?
13.61 billion years
How old is the universe thought to be?
13.7 billion years
True or False: Gravity is a pushing force.
False
It is an attractive force
How many galaxies are typically in a “local group”?
Several dozen at most
What holds all the stars, solar systems, and galaxies together in the universe?
Gravity
What is a requirement of gravity?
The objects involved MUST have MASS. Gravity is influenced primarily by MASS.
Distance only affects the strength of the gravity, it does not determine whether gravity exists.
What is the Local Group?
The group of galaxies that includes the Milky Way.
What is a Galaxy Group?
A group of galaxies, typically composed of a few dozen systems, not more than 100.
What is a Galaxy Cluster?
A larger group of galaxies than a galaxy group, containing a large number of galaxies, between 100 and 1000.
What is a galaxy?
A huge collection of gas, dust, and billions of stars and their systems all held together by gravity.
What is gravity?
The attractive force that holds all things in the universe together. One of the most powerful forces in the natural world.
What is the order of planets in our solar system, beginning closest to the sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What causes planets to form?
Gravity pulling dust and gas together in the universe.
All the planets in our solar system were formed billions of years ago.
Where is the asteroid belt in our solar system?
Between Mars and Jupiter. It separates the small planets from the gas giants.
What are asteroids?
Rocks that orbit the sun that are smaller than planets. They are made of nickel and iron.
True or false: Asteroids are round.
False
Where is the Oort cloud located in our solar system?
Beyond Neptune, the farthest planet from our sun.