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      Question: Earth has several natural satellites.
      Answer: Many artificial satellites circle Earth, but only one is natural: the Moon.
      Question: Earth’s atmosphere is composed of nearly 100 layers.
      Answer: Earth’s atmosphere is made up of five layers. From closest to most distant, they are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
      Question: Nitrogen is very rare in Earth’s atmosphere.
      Answer: Nitrogen composes about 78 percent of the lower atmosphere. Oxygen, argon, and other gases compose the rest.
      Question: Life began on Earth soon after the planet was formed.
      Answer: Earth is about 4.5 billion years old. Life began about 4 billion years ago, which, in geological time, is considered to be very soon after the planet formed.
      Question: The Pacific plate is the fastest-moving of the Earth’s plates.
      Answer: The Pacific plate, which underlies most of the Pacific Ocean, is moving at a rate of about 7.2 inches (18.3 centimeters) a year. Most of the other plates are about half as fast.
      Question: Because of volcanic action, Earth is constantly getting bigger.
      Answer: Though volcanoes produce new rocks, other rocks are "eaten" by Earth’s moving plates. The planet’s size remains constant as a result.
      Question: Earth’s interior has four major layers.
      Answer: Earth is made of concentric layers of rock. From outward to inward, they are the lithosphere, the mantle, the outer core, and the inner core.
      Question: Earth is a giant magnet.
      Answer: Earth behaves like a giant magnet, with metals such as nickel and iron flowing through the core and producing an electric current.
      Question: Earth has geomagnetic poles.
      Answer: Our planet has two magnetic poles, one in the Arctic and one in the Antarctic. They sometimes reverse polarity, and no one is quite sure why this happens.
      Question: Earth’s stratosphere is very cold.
      Answer: Reaching to 50 miles (80 kilometers) away from Earth, the stratosphere is very cold: it is about –148 oF, or –100 oC.
      Archaea at Midway Geyser Basin in the Grand Prismatic Spring, Yellowstone National Park, Wyoming. Largest hot spring in Yellowstone, third largest in the world. Temp. 147-188F Dim. 250x380 ft. Archaeon, archeon, Yellowstone Geysers, algae

      Earth Sciences: Fact or Fiction?

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