IN: What objects make up our solar system? The Planets 20-1 pgs. 538-548 IN: What objects make up our 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.

Small Rocky Worlds Terrestrial Planets – the small, dense, rocky planets of the inner solar system. · Mercury · Venus · Earth · Mars

Terrestrial Planets

Mercury Mercury is solid and is covered with craters. Mercury has almost no atmosphere. Has no moon.

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. Also, has no moon.

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.

Moons of Mars Phobos Deimos

Asteroid Belt

Big Gaseous Worlds Gas Giants – the large, gaseous planets of the outer solar system. · Jupiter · Saturn · Uranus · Neptune All gas giants have rings!

Gas Giants

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. In 2004 we got images of the rings.

Rings of Saturn Saturn’s rings are not solid; they consist of icy particles that range in size from a few centimeters to several meters across. The rings are very thin. Though they’re 250,000km or more in diameter, they’re less than one kilometer thick.

Uranus Uranus is blue-green because of the methane in its atmosphere. Its axis is tilted 90o.

Neptune Neptune is the fourth largest planet and the eight from the sun. Like Uranus, the methane gives Neptune its color.

Pluto Pluto – doesn’t fit either category. Pluto is a small icy world clearly different from either the Terrestrial and Gas Giant worlds.

Dwarf Planets Ceres – discovered on January 1, 1801, 45 years before Neptune. Considered a planet for half a century before reclassification as an asteroid. Accepted as a dwarf planet by the IAU on September 13, 2006. Pluto – discovered on February 18, 1930. Classified as a planet for 76 years. Reclassified as a dwarf planet by the IAU on August 24, 2006. Haumea – discovered on December 28, 2004. Accepted by the IAU as a dwarf planet on September 17, 2008. Makemake – discovered on March 31, 2005. Accepted by the IAU as a dwarf planet on July 11, 2008. Eris – discovered on January 5, 2005. Called the "tenth planet" in media reports. Accepted by the IAU as a dwarf planet on September 13, 2006.

Kuiper Belt

OUT: Summarize the differences between terrestrial planets and gas giants.