THE SOLAR SYSTEM

The Inner Planets

The inner planets are the 4 planets closest to the sun:

Mercury Venus Earth Mars The four inner planets are small and

dense and have rocky surfaces.

Mercury

Mercury is the smallest terrestrial planet and the planet closest to the sun.

Mercury’s diameter is about 3,000 miles. Mercury’s distance from the sun is about

36 million miles. Mercury’s revolution around the sun

takes about 88 days. Mercury’s rotation on its axis takes about

59 days.

Mercury

Mercury has flat plains and craters on its surface.

Mercury has no atmosphere. Mercury is a planet of extremes, with

greater temperature ranges than any other planet in the solar system.

Mercury

It is so close to the sun that during the day , the side facing the sun reaches temperatures of 806 degrees F.

At night, because Mercury has no atmosphere it drops to as low as -274 degrees F.

Mercury has no moons or rings.

Venus

Venus is similar in size and mass to Earth. It is sometimes called Earth’s twin.

Venus’s diameter is about 7,500 miles. Venus’s distance from the sun is about 67 million

miles. Venus is covered with rock and has many

volcanoes, plains, and lava flows. Revolution around the sun: 7 Earth months

(about 210 days) . Rotation: 243 days It rotates so slowly, its day is longer than its

year!

Venus

Venus rotates east to west, the opposite direction of most other planets.

Venus’s atmosphere is so thick that it is always cloudy there.

From Earth, astronomers can view a large cloud.

The clouds are made up mostly of droplets of sulfuric acid.

Venus

If you could stand on Venus’s surface, you would quickly be crushed by the weight of its atmosphere.

The atmosphere is 90 times greater than the Earth’s atmosphere.

You could not breathe on Venus because its atmosphere is mostly carbon dioxide.

Venus

Many probes have visited Venus to gather information. The first probe landed on Venus in 1970.

Venus has no moons or rings.

Earth

Earth is the only planet to have liquid water at its surface.

70% of Earth’s surface is by water. Earth has a suitable temperature

range to have water as a solid, liquid, and gas.

Earth has enough gravity to hold on to the gases. These gases make up Earth’s atmosphere.

Earth

Earth has an atmosphere that is rich in oxygen.

The Earth’s atmosphere is about 21% oxygen and 78% nitrogen.

Earth’s revolution around the sun takes about 365 ¼ days.

Earth’s rotation on its axis takes about 24 hours.

Earth

Earth is about 94 million miles away from the sun.

Earth’s diameter is about 8,000 miles.

Earth has 1 moon and no rings.

Mars

Mars is called the red planet.

Mars has a reddish color due to the iron –rich rocks that cover most of its surface.

Mars has an atmosphere that is 95% carbon dioxide.

Mars

We can view Mars from Earth with a telescope because it has a thin atmosphere with a few clouds.

Temperatures on Mars range from -220 F to 20 degrees F.

The revolution of Mars around the sun takes about 687 days.

Mars

The rotation of Mars on its axis takes about 24 hours and 39 minutes.

The diameter of Mars is about 4,221 miles. Mars is approximately 141 million miles

from the sun. Some regions of Mars has volcanoes. Mars

contains the largest inactive volcano in the solar system: Olympus Mons.

Mars

Scientists believe the a large amount of water once flowed on Mars.

At present, liquid water cannot exist on Mars because its thin atmosphere would cause evaporation to occur.

The water that once existed is now frozen in polar ice caps with carbon dioxide and small amounts of water vapor.

Mars has a tilted axis similar to the Earth; therefore, scientists believe it has seasons similar to Earth.

Mars has 2 moons and no rings.