1. An overview of the Solar System
The Planets
An overview of the
Solar System

2. The Sun
The sun is the biggest, brightest, and hottest object in the solar system.
The sun is an ordinary star.
The sun is made of about 70% hydrogen and 28% helium.

3. Mercury Mercury is solid and is covered with craters.
Mercury has almost no atmosphere.
Mercury is the eighth largest planet.

4. Venus
Venus is the sixth largest planet. It’s about three-fourths the size of earth.
The surface is rocky and very hot. The atmosphere completely hides the surface and traps the heat.

5. Earth Earth is the fifth largest planet and the third from the sun.
Liquid covers 71 percent of the Earth’s surface.
The Earth has one moon.

6. Mars Mars is the fourth planet from the sun.
Mars has a thin atmosphere that contains mostly carbon dioxide.
Mars has two small moons.

7. Jupiter’s Red Spot
The Great Red Spot, a huge storm of swirling gas that has lasted for hundreds of years.
Jupiter does not have a solid surface. The planet is a ball of liquid surrounded by gas.

8. Moons of Jupiter
Jupiter has four large Galilean moons, twelve smaller named moons and twenty-three more recently discovered but not named moons.

9. Saturn Saturn is the second largest planet and the sixth from the sun.
Saturn is made of materials that are lighter than water. If you could fit Saturn in a lake, it would float!

10. Rings of Saturn
Saturn’s rings are not solid; they are composed of small countless particles.
The rings are very thin. Though they’re 250,000km or more in diameter, they’re less than one kilometer thick.

11. Uranus
Uranus is the third largest planet and the seventh from the sun.
Uranus is one of the giant gas planets.
Uranus is blue-green because of the methane in its atmosphere.

12. Neptune
Neptune is the fourth largest planet and the eight from the sun.
Because of the orbits, from 1979 to 1999, Neptune was the ninth planet.
Like Uranus, the methane gives Neptune its color.

13. Pluto
Pluto is the smallest planet and usually the farthest from the sun.
Pluto is the only planet that has not been visited by a spacecraft.

15. Asteroid Belt Between Mars and Jupiter
Between 700,000 and 1.7 million asteroids

16. Kuiper Belt Outside Neptune At least 70,000 objects
Short-period comets
Less than 200 year orbit

17. Oort Cloud Far beyond the orbit of Pluto Long-period comets
More than 200 year orbit