Our Solar System

1. Our Solar System • 8 Major Planets • The Sun • 4 Inner Planets • Mercury • Venus • Earth • Mars • 4 Outer Planets • Jupiter • Saturn • Uranus • Neptune

2. Other Objects in the Solar System • Dwarf Planets • Dwarf planets orbit the Sun but are not large enough to be considered planets. • Ex: Eris, Ceres and Pluto • Asteroid Belt • Located between Mars and Jupiter • Asteroids are irregularly shaped rocky bodies • Most, but not all asteroids are in the Asteroid Belt • Ceres is in the Asteroid Belt • Kuiper Belt • Contains comets and dward planets orbiting the Sun • Comets are irregularly shaped bodies of ice and dust • Oort Cloud • Sphere of comets around Sun • Never observed; based on data

3. The Sun At the very center of the Solar System is the Sun. The Sun is a star, a massive ball of gas which produces huge amounts of heat and light. It is the key reason why the planets in the Solar System are present, and why life on Earth is able to exist. Without the Sun, there would be no light, no warmth, no water, no plants, animals or people.

4. Mercury Mercury is the closest planet to the Sun 36 million miles away from the Sun, 88 days to orbit the Sun. Temp: 662 F and -274 F It has the most cratered surface of any planet in the Solar System. Has no atmosphere.

5. Venus Venus is the second planet away from the Sun The closest planet to Earth. It is the brightest object in the sky after the Sun and the Moon It has a poisonous atmosphere and deadly volcanic surface The planet has a thick swirling cloud cover which never clears to reveal the surface. Hotter than Mercury.

6. Earth • Earth is the third planet from the Sun and the largest of the four Inner Planets. • It is in the perfect position in the Solar System - not too close to the Sun and not too far away - meaning that it has the right climate for life to exist - not too hot nor too cold. • It also has plenty of water, a key ingredient for all living things. • A magnetic field protects Earth. • Like other planets and moons, it is a target for asteroids and meteorites travelling through space. Most of these objects burn up in the planet's protective atmosphere, although some do survive and leave huge impact craters. • Earth is gradually slowing down. Millions of years ago, a day on Earth will have been 20 hours long. It is believed that, in millions of years time, a day on Earth will be 27 hours long.

7. Mars Mars is the fourth planet from the Sunand the last of the four Inner Planets. Has 2 Moons. 141,700,000 miles from the Sun, 687 days to orbit the Sun -81 F Mars is believed to have had water flowing around it like Earth once. It may have had a blue sky too. However, it is unlikely that it had grass, trees and plants like Earth has now. Mars has seasons like Earth. This is caused by the tilt of the planet's axis, at a similar angle to the tilt of Earth's axis.

8. Jupiter Has 63 moons. 483,500,000 miles from the Sun, Orbits the Sun in 11.86 years -202 F Jupiter is the biggest planet in the Solar System and has a very strong pull of gravity and very faint rings spinning around it, just like Saturn's rings Jupiter is made up almost entirely of gas. This means that the whole planet is just like sky without any land below it. In this sky are electrical storms (lightning) and winds and hurricanes.  Great Red Spot, which is a storm that was first observed by an astronomer called Robert Hooke in 1664!

9. Saturn 61 moons 888,700,000 miles from the Sun, 29 years to orbit the Sun -202 F The second largest planet in the Solar System Saturn is famous because of the amazing rings that orbit the planet. The planet is mainly made up of gas and has been visited by the Voyager probes in the early 1980s and more recently by the Cassini probe. Orbiting Saturn are at least 60 known moons including a moon called Titan which has an atmosphere that may have been like Earth's during its formation.

10. Uranus 1,783,000,000 miles from the Sun, 84 years to orbit the Sun 27 moons -328 F The seventh planet in the Solar System is Uranus. It was discovered by William Herschel, an English astronomer and composer, in March 1781 using a home-made telescope. Uranus is visible from Earth without a telescope as a very faint star. Even close up, the Voyager 2 spacecraft revealed little about the planet. A gigantic pale blue ball of hydrogen, helium and methane gas (methane filters out red light, so the planet appears blue).

11. Neptune 13 moons 2,797,700,000 miles from the Sun, 164.8 years to orbit the Sun. 8th Planet from the Sun. Neptune is often seen as Uranus' twin planet. It is similar in size and color, and has a similar chemical make-up Temp: -328 F