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William Kenneth Hartmann is an American planetary scientist, artist, author, and writer. He was the first to convince the scientific mainstream that the Earth had once been hit by a planet sized body (Theia), creating both the Moon and the Earth's 23.5° tilt.
William Kenneth Hartmann is an American planetary scientist, artist, author, and writer. He was the first to convince the scientific mainstream that the Earth had once been hit by a planet sized body (Theia), creating both the Moon and the Earth's 23.5° tilt.
