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Sun and Planets
Background Information Earth Sun Solar System Glossary Activities References

Sun
The sun is a "star" that is the central and largest body is our solar system. Scientists estimate that the sun began to form about five billion years ago. The sun is the major source of energy for such things on the earth as growth of plants, winds, ocean currents, and the water cycle.

The Sun brings heat and light to the Earth. The heat and light travel from the Sun to the Earth. The sunlight is made up of photons. Trillions of photons make up the sunlight we see.

Even though the Sun is of average size star, it dwarfs our Earth. More than a million Earths could fit inside the Sun.

The Sun is boiling and is always changing. It shapes our lives on Earth through climate, weather, and other ways.

Our seasons result from the way the sun's energy strikes the Earth's surface, due to the tilt of the Earth's rotation.

OUR SOLAR SYSTEM Actual Diameter (km) Mean Distance From Sun (km) No. of Moons
Sun 1,391,900    
Mercury 4,878 57,910,000 0
Venus 12,104 108,200,000 0
Earth 12,756 149,600,000 1
Moon 3,476    
Mars 6,794 227,940,000 2
Jupiter 142,984 778,330,000 16
Saturn 120,536 1,429,400,000 18
Uranus 51,118 2,870,990,000 15
Neptune 49,528 4,504,300,000 8
Pluto 2,300 5,913,520,000 1

 

Glossary
Astronomy The study of the universe beyond the Earth.
Asteroid A rocky object that is smaller than a planet that orbits the Sun.
CometA small body made of dust and ice that orbits the Sun.
MeteoroidSmall particles of matter in the solar system.
PlanetA large rotating body that orbits a star. Planets reflect starlight.
SatelliteA moon or man-made body.
StarA hot glowing sphere of gas
Solar SystemThis is our Sun (a star), nine planets, more then 50 moons, asteroids, meteroids, and comets.

Activities
How big is our solar system? To give you a rough idea, consider that it took the Voyager 2 spacecraft, traveling in a sweeping arc at an average 65,000 kilometers (40,000 miles) per hour, 12 years to reach Neptune! How fast is that in meters per second? In feet per second? If you could travel that fast, how long would it take you to reach the next town? To get to the Moon?

Can you build a scale model of the solar system? If you use Earth's diameter as a unit of measure (Earth diameter = 1 ), figure out how big the other planets are compared to Earth. Hint: divide each planet's diameter by Earth's diameter. What objects might you use to depict the sizes of the Sun and planets? How far away would the planets be from each other? Map out a scale model of the solar system.

References

These web sites contain additional information that may be researched.

Physical Science Earth Link
AZ Science link
NASA

Additional mini-quiz
http://www.ronkurtus.com/physcien/earth.htm

A good reference book is the"National Geographic Picture Atlas of Our Universe," by Roy A. Gallant, 1996, National Geographic Society, Washington, D. C.

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