An overview of the Solar System Astronomy An overview of the Solar System

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.

Planets can be categorized in two ways: Inner Planets (Terrestrial) Planetary Categories Planets can be categorized in two ways: Inner Planets (Terrestrial) Outer Planets (Gaseous)

Inner Planets (Terrestrial)

Mercury Mercury is solid and is covered with craters. Mercury has almost no atmosphere. Mercury is the eighth largest planet. 36 million miles away from the Sun

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. 67 million miles

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.

Moon

Mars Mars is the fourth planet from the sun. Mars has a thin atmosphere that contains mostly carbon dioxide. Mars has two small moons. 142 million miles

Moons of Mars Phobos Deimos

Jupiter

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.

Moons of Jupiter Jupiter has four large Galilean moons, twelve smaller named moons and twenty-three more recently discovered but not named moons. We’ll take a look at the four large Galilean moons which were first observed by Galileo in 1610.

Io Io is the fifth moon of Jupiter. It’s the third largest of Jupiter’s moons. Io has hundreds of volcanic calderas. Some of the volcanoes are active.

Europa Europa is the sixth of Jupiter’s moons and is the fourth largest. It is slightly smaller than the Earth’s moon. The surface strongly resembles images of sea ice on Earth. There may be a liquid water sea under the crust. Europa is one of the five known moons in the solar system to have an atmosphere.

Ganymede Ganymede is the seventh and largest of Jupiter’s known satellites. Ganymede has extensive cratering and an icy crust.

Callisto Callisto is the eighth of Jupiter’s known satellites and the second largest. Callisto has the oldest, most cratered surface of any body yet observed in the solar system.

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!

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 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.

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.