Chapter 18Chapter 18

Lesson 1Lesson 1What Makes up the What Makes up the

Universe?Universe? The The universeuniverse is all of space and is all of space and

everything in it.everything in it.

A Galaxy is a system of dust, gas, A Galaxy is a system of dust, gas, and many millions of stars held and many millions of stars held together by gravity.together by gravity.

We live in the Milky Way Galaxy. The Milky We live in the Milky Way Galaxy. The Milky Way is shaped like a flat spiral.Way is shaped like a flat spiral.

AstronomyAstronomy is is the study of the the study of the Sun, Moon, stars, Sun, Moon, stars, and the other and the other objects in space.objects in space.

The Solar SystemThe Solar System

The Solar System includes the Sun, The Solar System includes the Sun, the planets, their moons, and other the planets, their moons, and other objects.objects.

Gravity is the force that keeps Earth Gravity is the force that keeps Earth and other objects in their orbitsand other objects in their orbits

The Sun is so massive that its gravity The Sun is so massive that its gravity pulls the planets toward it. pulls the planets toward it.

gravity videogravity video

Inner PlanetsInner Planets

MercuryMercury Closest plant to the Sun. Closest plant to the Sun. Covered with craters or dents shaped like Covered with craters or dents shaped like

bowlsbowls Mercury is extremely hot during the day and is Mercury is extremely hot during the day and is

very cold at night because there is not an very cold at night because there is not an atmosphere to keep in the heat.atmosphere to keep in the heat.

The Mariner 10 is a space probe that visited The Mariner 10 is a space probe that visited Mercury in 1974. A space probe is a vehicle Mercury in 1974. A space probe is a vehicle that carries cameras and other tools for that carries cameras and other tools for studying different objects in space.studying different objects in space.

VenusVenus Venus rotates in the opposite Venus rotates in the opposite

direction than Earth.direction than Earth. Venus has an atmosphere, but Venus has an atmosphere, but

the clouds are poisonous.the clouds are poisonous. The clouds reflect the Sun’s light The clouds reflect the Sun’s light

which makes it one of the which makes it one of the brightest objects in the sky.brightest objects in the sky.

Mars Mars 44thth planet from the Sun planet from the Sun Soil contains iron oxide, which gives Soil contains iron oxide, which gives

it a reddish-brown color. Called the it a reddish-brown color. Called the “Red Planet”“Red Planet”

Has 2 moonsHas 2 moons Mars video 10 minutesMars video 10 minutes

Gas PlanetsGas Planets Jupiter—5Jupiter—5thth planet from the Sun planet from the Sun Gas gaint—a planet made of mostly gasesGas gaint—a planet made of mostly gases Largest planet in our solar systemLargest planet in our solar system It is so large that if it was hollow inside all It is so large that if it was hollow inside all

the other planets would fit inside.the other planets would fit inside. Has a large red spot which is actually a Has a large red spot which is actually a

large storm.large storm. Has rings that are very dark and can not be Has rings that are very dark and can not be

seen from Earth.seen from Earth. Video on Gas Planets (2:13 minutes)Video on Gas Planets (2:13 minutes)

Saturn 6Saturn 6thth planet from the Sun planet from the Sun Is a gas giantIs a gas giant Has large rings. The rings are made up Has large rings. The rings are made up

of everything from dust to large of everything from dust to large boulders.boulders.

Galieo saw the rings from earth and Galieo saw the rings from earth and thought they were handles in the 1600’sthought they were handles in the 1600’s

Has 34 moons.Has 34 moons.

UranusUranus 77thth Planet from the Sun Planet from the Sun A gas giant A gas giant Rotates on its sideRotates on its side This is the largest planet you can see This is the largest planet you can see

from earth with out a telescope.from earth with out a telescope. Atmosphere is made up of methane Atmosphere is made up of methane

which is a liquid and gives Uranus its which is a liquid and gives Uranus its fuzzy blue-green lookfuzzy blue-green look

Has at least 27 moonsHas at least 27 moons

NeptuneNeptune 8 8thth Planet Planet Smallest of the gas planets, but it is Smallest of the gas planets, but it is

still very large. It could hold 60 still very large. It could hold 60 Earths inside if it was hollow.Earths inside if it was hollow.

Has strong winds that blow huge Has strong winds that blow huge storms across the planet.storms across the planet.

Has at least 13 moons. One of its Has at least 13 moons. One of its moons is the coldest body in our moons is the coldest body in our entire Solar System -235 Centire Solar System -235 C

Magic School Bus Space Video (29 Magic School Bus Space Video (29 minutes)minutes)