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• 7th Grade Home
• Help I'm Drowning
• How Dense Can You Get?
• Sort It Out!
• The Denser You Are, The Harder You Fall
• What Was Up ... Must Come Down!
• How Do The Densities of Earth's Layers Compare?
• How Many Licks Does It Take To Get To The Center?
• Let's Build the Earth!
• What's Wrong With It?
• Science Language

Earth's Structure - How Many Licks Does it Take to Get to the Center?

Earth's Atmosphere

The first layer encountered when investigating Earth is the atmosphere. The atmosphere is actually composed of four layers: the thermosphere, the mesosphere, the stratosphere, and the troposphere.  The troposphere makes up 90% of the mass of the atmosphere. The atmosphere is the least dense layer of the earth.  The atmosphere is composed of 78%  nitrogen 21% oxygen, and 1% other gases.