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The EarthYes! You've found the Earth, a habitable planet! The Earth is the solar system's fifth largest planet in diameter and its most dense. The Earth is the only planet in the solar system that has oxygen in the atmosphere and liquid water, which covers almost three-quarters of the planet's surface. The Earth's oceans also help maintain the planet's moderate temperatures.

There was probably much more carbon dioxide in the Earth's atmosphere when the Earth was first formed and when the first basic cellular life started.

Photo courtesy NASA

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