Our Solar System

The Sun The sun is the biggest, brightest, and hottest object in our solar system. The sun is an ordinary star. The sun is made of about 70% hydrogen and 28% helium. It makes up almost 99% of our solar system’s mass!

THE INNER PLANETS Rocky, cratered surfaces Much smaller than the other planets Much closer to the Sun than the other planets Have no, or very few moons compared to the other planets

Mercury (Roman messenger god) Mercury is solid and is covered with craters. Mercury has almost no atmosphere, but water vapour has been found. Mercury is the smallest planet.

Venus (Roman goddess of beauty) It’s almost the same size as Earth. The surface is rocky and very hot with volcanoes and mountains. The atmosphere completely hides the surface and traps the heat. Days are longer than years!

Earth Earth is the fifth largest planet and the third from the sun. Liquid covers almost 75 percent of the Earth’s surface. The Earth has one moon.

Mars (Roman god of war) Mars is the fourth planet from the sun. Mars has a thin atmosphere that contains mostly carbon dioxide. Mars has two small moons, rust in the soil, and maybe life.

THE OUTER PLANETS Gassy atmosphere with no solid surface Very large compared to inner Far away from the Sun Have rings Have numerous moons

Jupiter (Roman ruler of gods/goddesses) The largest planet. Does not have a solid surface. It is a ball of liquid surrounded by gas – mostly hydrogen and helium. The Great Red Spot, a huge storm of swirling gas, has lasted for hundreds of years.

Saturn (Roman god of agriculture) Saturn is the second largest planet. Saturn is made of materials that are lighter than water. If you could fit Saturn in a lake, it would float! 61 known moons.

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.

Uranus (Greek god of the sky) Composed mostly of hydrogen and helium. Looks blue-green because of the methane in its atmosphere. 27 known moons. Has a faint ring system. Rotates on a 90o tilt!

Neptune (Roman god of the sea) Average temperature of -235oC. Composed of mostly hydrogen and helium. Orbit takes it beyond Pluto. Like Uranus, the methane gives Neptune its color.

CLICK TO CHECK THESE OUT! The Solar System : A Brief Glance The Solar System – Space School Why isn’t Pluto a planet anymore?