What is a galaxy?
A galaxy can be defined as billions of gas, dust, and stars held together by gravity. The three main types of galaxies are Elliptical, Spiral, and Irregular.
Because distances in space are so great, astronomers use light years to measure the distance to stars and galaxies in space. A Light Year is the distance light travels in a year.
Because distances in space are so great, astronomers use light years to measure the distance to stars and galaxies in space. A Light Year is the distance light travels in a year.
Elliptical galaxy
An elliptical galaxy looks like a spherical or flattened disk.
spiral galaxy
A spiral galaxy is a nucleus of bright stars and two or more spiral arms. Our solar system is in a spiral galaxy called the Milky Way Galaxy. We are located about 2/3 of the way from the center of the galaxy in a spiral arm.
Irregular galaxy
An irregular galaxy has no definite shape.
earth's place in the universe
From smallest to largest:
Earth
Solar System
Galaxy
Universe
Earth
Solar System
Galaxy
Universe
Mass vs. weight
Mass - amount of matter in an object, never changes, measured using a triple beam balance
Weight - measure of the pull of gravity of an object, changes with the gravitational pull, measured using a spring scale
Weight - measure of the pull of gravity of an object, changes with the gravitational pull, measured using a spring scale