The Solar System

The Sun The Sun is our closest star. Is a member of the Milky Way galaxy. Is a medium size star. It is believed to be about 4.6 billion years old. (The age of an average star is about 5 billion years old.). The diameter of the Sun is 1,392,000 kilometers. Temperature ranges from 5,800o Celsius (C) to over 15,600,000o C at its core.

The Sun In the Sun's core, hydrogen is fused to form helium in a process called fusion. The sun is composed of gas: 75% hydrogen, 25% helium, and 0.1% metals.

The Eight Planets Mercury Venus Earth Mars Neptune Saturn Jupiter Uranus

Mercury – Closest to the Sun 1st planet from the sun 3.2 Light minutes from the sun. diameter of 4,879 km Terrestrial planet – composed of iron and silica.

Mercury No satellites / no rings. Temperature ranges from –173o C to Very thin atmosphere. Fun Fact: The temperature on Mercury gets so hot it could melt a tin pan.

Venus- Earth’s Twin 2nd planet from the sun 6.0 Light minutes from the diameter of 12,104 km Terrestrial planet – basically the same as Earth.

Venus No satellites / no rings. Temperature is 464o C. The hottest planet due the largest amount of greenhouse gases. Atmosphere is mostly carbon dioxide. Fun Fact: Venus is called the Evening Star. It is called this because it looks so bright to us from Earth.

Earth- The Water Planet 3rd planet from the sun 8.3 Light minutes from the sun. diameter of 12,756 km Terrestrial planet – iron, oxygen, silicon, and magnesium.

Earth 1 satellite / No rings Temperature ranges from –13o C to 37o C. Atmosphere is 77% nitrogen and 21% oxygen. Fun Fact: Seventy percent of the Earth's surface is covered by water. The remaining 30 percent is covered by mountains, volcanoes, deserts, plains, and valleys.

Mars- The Red Planet 4th planet from the sun 12.7 Light minutes from diameter of 6,794 km Terrestrial planet – sulfur and iron

Mars 2 satellites / No rings. Temperature ranges from –123o C to 37o C. Atmosphere is 95.3% carbon dioxide and 2.7% nitrogen. Fun Fact: Some of the meteorites found on Earth are actually pieces of the planet Mars. As of June 2006, 34 “Martian meteorites” have been found.

Jupiter- The Largest Planet 5th planet from the sun 43.3 Light minutes from the sun. diameter of 142,984 km Gas giant – hydrogen, helium, and ammonia

Jupiter 50 satellites / 3 rings. Temperature is -153O C. Atmosphere is 90% hydrogen and 10% helium. Fun Fact: Jupiter is so large that all of the other planets in the solar system could fit inside of it.

Saturn- The Ringed Planet 6th planet from the sun 1.3 Light hours from the sun. diameter of 120,536 km Gas giant – hydrogen & helium Click here to learn more about Saturn.

Saturn 53 satellites / 14 rings. Temperature is -185O C. Atmosphere is 75% hydrogen and 25% helium. Fun Fact: Saturn has the lowest density of any planet in our solar system. Its density is so low that it would float, if it was placed in water.

Uranus- Neptune’s Twin 7th planet from the sun 2.7 Light hours from the sun. Diameter of 51,118 km Gas giant – water, methane, ammonia ice Click here to learn more about Uranus.

Uranus 27 satellites / 11 rings. Temperature is -214o C. Atmosphere is 83% hydrogen, 15% helium, and 2% methane. Fun Fact: Uranus is one of the smaller gas giants in our solar system, but it is still large enough to hold 64 planets the size of Earth.

Neptune – The Blue Planet 8th planet from the sun 4.2 Light hours from the sun. diameter of 49,528 km Gas giant –water, methane, ammonia Click here to learn more about Neptune.

Neptune 13 satellites / 4 rings. Temperature is -225o C. Atmosphere is 80% hydrogen, 19%helium and 1% methane. Fun Fact: It is so cold on Neptune that you would need skin thicker than a polar bear's to stay warm.

Moon A moon is a natural satellite of a planet. The Earth’s moon is called Luna. Earth has only 1 moon. Jupiter has about 50.

Earth’s Moon Composition: Solid Orbit / Location: 384,400 km from Earth Position in Space: Orbits the Earth How is it classified? Terrestrial “planet” due to its size and composition. Fun Facts: The gravity between the Earth and the Moon causes the tides. The moon has no atmosphere.

Comets A comet is a small body of ice, rock and cosmic dust loosely packed together. It is made up of a nucleus, with a cloud that surrounds it, and a tail.

Comets Composition: Solid – frozen water, gases, and dust. Orbit / Location: Eccentric; takes them far beyond the orbit of Pluto. Position in Space: Orbits the Sun How are they classified? By their orbital period. Fun Facts: May travel out of the solar system for hundreds of years. Sometimes called “dirty snowballs”.

Asteroids Composition: Solid Orbit / Location: Usually orbit the sun in specific places but a few have planet-crossing orbits. Position in Space: The Asteroid Belt is a region between the inner planets and outer planets where thousands of asteroids are found orbiting around the Sun.

Asteroids How are they classified? Number of types according to their spectra (chemical composition), albedo (The albedo of an object is the extent to which it reflects light from the sun), and their position in the solar system. Fun Facts: January 1801 – first object observed that would be classified as an asteroid.

Asteroid Belt More than 7000 asteroids have been discovered. Several hundred more are discovered each year. There are undoubtedly hundreds of thousands more that are too small to be seen from the Earth. The “Main Belt” is between Mars and Jupiter.

Meteors Composition: Solid. Orbit / Location: Irregular because they are bits of material loose in space. Position in Space: Asteroid material until they enter Earth’s atmosphere. How are they classified? According to whether they enter the Earth’s atmosphere and burn up or strike the Earth’s surface. Interesting Facts: Most burn up on entry into the Earth’s atmosphere. These are what we call shooting stars.

Meteorites Composition: Solid. Orbit / Location: Irregular because they are bits of material loose in space. Position in Space: Asteroid material until they enter Earth’s atmosphere, at which time they are called meteoroids. How are they classified? According to whether they enter the Earth’s atmosphere and burn up or strike the Earth’s surface. Fun Fact: When a meteoroid hits the ground, it’s called a meteorite.