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Study Guide                                                                                                                    Period__




Rocky world, cratered surface with almost no atmosphere

Sun appears 9 times as large as it does from the Earth because Mercury is the

Closest planet to the sun

Moves more quickly around the sun than any other planet (88 days to complete one revolution)

 Named after speedy messenger of the Roman gods

 No rings

 No moons

Very slow rotation time. (59 Earth days for one rotation.)

Revolution  (88 Earth Days)  About 3 rotations for every two revolutions around the sun.

Temperature cold at night Hot during the day





Named for the Roman goddess of beauty and love

Same diameter, mass and density as Earth so astronomers call it the Earth's twin

Very thick cloud covering (5 times as dense as earth) – Greenhouse Effect

**Year shorter than day

95% of its atmosphere is C02

Has craters

 no rings

 no moons

 Brightest planet in the sky

 2nd planet from the sun

 Closest planet in size to the earth

 Covered in volcanic rock



MARS (The Rusty Planet)


 Known as The Red Planet (rust)

 Surface is rocky and heavily cratered

 Martian soil is coated with a reddish compound called iron oxide (commonly known as Rust!)

In ancient times this color reminded people of blood and they thought of Mars as a warrior planet

 Named after the Roman god of war

 Two tiny moons that circle Mars are called Phobos and Deimos (from the Greek-words for fear and terror)

4th planet from the sun

Gravity close to 1/3 of Earth's

 2 moons (Phobos and Deimos)

 4 large, inactive volcanoes, Polar Icecaps


 Has a rotation time most similar to Earth's (about a 24.5 hour day)





One hundred Earths could be strung around Jupiter as if they were a string of pearls

 Jupiter is so big and bright in the night sky that the Romans named this planet after their king of gods

 Made primarily of hydrogen and helium gases

At its core, scientists believe temperatures may reach 5 rimes that of the sun

5th planet from the sun

*Shortest rotation time (shortest day – 10 hours)

Largest planet

 Hotter than earth

 Known for "Great Red Spot"

The red spot is a very large storm that has lasted for centuries

SATURN- (A world of many rings)

Famous for its rings

Rings made from rocks and ice

It's rings were discovered by Galileo

It's rings are made mainly of icy particles

Voyager revealed that Saturn has at least seven major rings, lettered from A to G

Saturn spins so fast that it is flattened at the poles and bulges at the equator

Has more moons (satellites) than any other planet

6th planet from the sun

Gas planet

Very little atmosphere

It's moon. Titan, is larger than the planet. Mercury



URANUS - (A planet on its side)

 Most distant planet that can be seen with the unaided eye

Known as one of the giant twins (along with Neptune)

Named for the father of Saturn in Roman mythology

With the discovery of Uranus, the solar system doubled because Uranus is almost twice as far from the sun as Saturn

A gas giant covered by a thick atmosphere made of hydrogen, helium and methane

Entire planet is tinged with a greenish-blue color

Covered by an ocean of superheated water that may have been formed from melted comets

The axis of Uranus is tilted at an angle of about 90°

Uranus spins on its side

 Has nine known rings

 7th  planet from the sun

Gas planet

21 satellites

11 rings



Named for the Roman god of the sea

The windiest planet

Neptune and Uranus are often called the twin giants because they are about the same size, mass and temperature

They both glow with a blue-green color

Surface is probably an ocean of water and liquid methane, covering a rocky core

Thick cloud coverage (Like Uranus)

Has five rings

Has at least eight moons

Triton 4th largest in the Solar System) An unusual moon that orbits Neptune in a backward direction. (retrograde)

Voyager discovered new moons and rings around Neptune in 1989


 PLUTO (A double planet)

Named for the Roman god of the underworld

Smallest and least massive planet

Farthest known planet from the sun

May be an escaped moon of Neptune

Made mainly of various ices, primarily methane ice

Pluto’s moon’s name is Charon.

Charon is about half the size of Pluto.  Because of the closeness in size, astronomers consider Charon and Pluto to be a double planet.



Largest object in the solar system

About 109 times the diameter of the Earth

If the sun were hollow, more than 1 million Earths’ could fit inside

Surface temperature is about 10,000° F

About 4.6 billion years old

Made of extremely hot gases

Four main layers of the sun (corona, chromosphere, photoshere, core)


Solar flare

Solar wind


Black Holes-



Often called a "snowball in space"



Also known as a "shooting star"

Chunks of rock in the Earth’s atmosphere



May be made of rocks, metals or a combination of the two

Known as “flying mountains” or “minor planets”

Most are small and irregularly shaped but a few are huge



Jupiter’s Major Moons-