Ch. 18Lesson 1

What makes up the universe?

universe•all of space & everything in it

galaxy•system of dust, gas & millions of stars held together by gravity

What galaxy do

we live in?

astronomy•study of Sun, Moon, stars & other objects in space

solar system•Sun, planets, their moons, etc.

–all revolve around Sun

Inv. 1 What is the Solar System Made of ?

Ch. 2

asteroid belt•group of asteroids located between inner & outer planets

asteroid•rocky object that orbits the Sun

•too small to be considered a planet

The Asteroid Belt [03:21]

planet star

•medium-sized star

•largest object in our solar system

•magnetic field

If the Sun were hollow, we could fit one million Earth-sized planets inside of it!

The sun’s gravity is the most powerful force in the solar system because the

sun’s mass is so large.

99.8 % of the mass of the solar system is in the sun.

universe•all of space & everything in it

asteroid•rocky object that orbits the Sun

•too small to be considered a planet

is a ____-sized

star.

medium

asteroid belt•group of asteroids located between inner & outer planets

astronomy•study of Sun, Moon, stars & other objects in space

galaxy•system of dust, gas & millions of stars held together by gravity

What galaxy do

we live in?

•largest body in our solar system