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The Solar System

The Sun
Relative Size of Planets
Comets, Asteroids, and Meteors
Planet X
CA Standards
About Us



Earth is a very important planet. As we all know, Earth is the only planet we know with life. Much is unsure about how Earth got life, but it is all centered around water. Earth is mostly made of water, which is a good indication that water causes life. About 20% of Earth's atmosphere is oxygenand almost all the rest is nitrogen gas. Earth makes a revolution every 23 hours, 56 minutes and 4.091 seconds. A revolution is considered a day. Calendars and clocks are made to make a day equal 24 hours instead. Earth orbits the sun  about every 365 days. The term 'earth' is derived from many dialects, ranging from Latin, to German, to the extinct tongue, known as Old Saxon. Earth has a diameter of 12,104 kilometers, making it the largest inner planet, or fifth largest in the solar system.

Earth is 149,668,992 km (93,000,000 mi) from the sun, making Earth have the perfect temperature for life, which is on average, 14C or 57.2F. The perihelion is 147,098,074 km (91402505 mi), and its aphelion is 149,597,887.5 km (92955817.7 mi). Earth's density is 5,515 km/m3 and the surface gravity is 9.78 m/s2.

Also, Earth has 3 layers. The crust, mantle, and the core. The crust is where we walk, while the mantle is where the land melts from pressure. The core is extremely hot, and filled with molten material. Together, they make up the earth as we know it. In fact, the ground we walk on is part of a series of plates that drift slowly in assorted directions. The collision of these plates causes earthquakes.

Earth is the planet we know the most about, so we use it as an example to compare other planets with. By observing our climates, atmosphere, oceans and the elements, we can learn about space without leaving our own planet!