what is earth

Topics: Plate tectonics, Earth, Mid-Atlantic Ridge Pages: 2 (713 words) Published: February 11, 2014
What is Earth’s mantle? The Earth's mantle is a roughly 1,800 mile (2,900 km) thick shell of compressed and heated rock, beginning below the Earth's crust (lithosphere), which extends 3.1 miles (5 km) below the ocean floor and 19 to 31 miles (30 to 50 km) below the continents. What elements make up the Earth’s mantle? magnesium, silicon, iron, and oxygen Describe the “big splash” theory of the Moon’s origin? The currently accepted hypothesis for the Moon's origin--which is supported by chemical analysis of Moon rocks--is that it began as part of Earth but was blown off when the early Earth was struck by a Mars-sized early planet (retroactively named Theia). Huge amounts of debris were ejected into orbit around the Earth, where most of it coalesced into the Moon. The other moons in the solar system have different origins. The small ones are mostly captured asteroids, I think, while many of the larger ones (e.g. Ganymede) are thought to have formed in orbit around their respective planets. How are comets different from asteroids? The main difference between an asteroid and a comet is what they are made of.

Of what are comets made? And asteroids? A comet usually consists of water and other sediments and gasses. Asteroids are usually made of rock and/or other metals. Asteroids that enter the earth's atmosphere are called meteors. Meteors usually burn up before reaching the surface of the earth. if you grew up on the moon, would your bones be heavier or lighter than they are now? It would be heavier. Look up New Horizons space probe. Where is it heading and where is it right now? The New Horizons spacecraft is now halfway between Earth and Pluto, on approach for a dramatic flight past the icy planet and its moons in July 2015. Where are the tallest and longest mountain chains on Earth? How were they formed? The longest mountain range on Earth is called the mid-ocean ridge. Spanning 65,000 kilometers (40,389 miles) around the globe, it's truly a global landmark. How...
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