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The
Earth

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The Earth is certainly the most familiar planet, though it has only been a few hundred years since we fully realized it was a planet. We begin our study of objects in the Solar System with the Earth because it is interesting in its own right, and it provides a test of many observing techniques that we wish to use for other objects in the Solar System.

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Here is an interactive viewer that displays either a map of the Earth showing the day and night regions at this moment, or a view of the Earth from the Sun, the Moon, the night side of the Earth, above any location on the planet specified by latitude, longitude and altitude, from a satellite in Earth orbit, or above various cities around the globe (Credit: John Walker). Here is the NASA Earth from Space image gallery, where you can find many images of the Earth taken from space.