Section 17.2 The Planets

Terrestrial Planets A Terrestrial planet that is composed primarily of silicate rocks or metals

Mercury Has a 88 day year Has temperature of 430 degrees Celsius at the equator. Very low gravity and a very thin atmosphere

Venus Similar in size to earth Due to atmosphere, it is 460 degrees day or night. Rotates very slow - 243 days to rotate on its axis Has a thick atmosphere which raises the temperature The surface is covered with volcanoes

Earth Where you live! Earth's atmosphere and temperature allow water to exist as a liquid. Earth is dense allowing it to have relatively high gravity which holds it's atmosphere in place.

Mars The most earthllike The reddish color comes from the "weathered" iron rich rocks that are on the surface Mars has a very thin atmosphere Mars has evidence of once having liquid on it's surface Mars has seasons

Gas Giants Planets A Gas Giant planet consist mainly of liquid hydrogen and helium

Jupiter Largest most massive planet Jupiter rotates rapidly - one day on Jupiter is less than 10 Earth hours Great Red Spot - a huge storm that rotates like a hurricane - first observed in 1664 Jupiter has 63 moons - Jupiter has the mass and gravity to hold over 1300 earth moons

Saturn Largest and most visible rings Rings are made of rock and ice Saturn has the largest atmosphere of all the planets Saturn is less dense than water and would float on water Saturn has at least 30 moons

Uranus Uranus's atmosphere is composed of lots of methane which gives it a blue color At least 20 moons Has rings but are not as visible as Saturn's The axis of Uranus rotates at a tilt of more than 90 degrees

Neptune 165 years to make one revolution around sun Blue color from methane atmosphere

Dwarf Planets A dwarf planet is an object orbiting the Sun that is large enough to be rounded by its own gravity but is not gravitationally dominant in its orbital area and is not a moon.

Pluto Smaller and more dense than the other planets Rotates on a 90 degree axis like Uranus Pluto has a single moon, Charon Pluto was demoted to a dwarf planet in 2006

Ceres Located in the asteroid belt

Eris Located in the Kuiper belt (Beyond Pluto)

Other Parts of our Universe

ASTEROIDS Large rock masses that orbit the sun, from the asteroid belt

COMETS Dusty pieces of ice and rock that vaporize when they pass near the sun; Come from the kuiper belt

A small rock that travels through the solar system METEOROIDS A small rock that travels through the solar system METEOR – a meteoroid that burn up in the earths atmosphere METEORITE – a meteoroid that makes it to the earth’s surface