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Lunar craters are craters on Earth's Moon. The Moon's surface has many craters, almost all of which were formed by impacts. ==History== The word ''crater'' was adopted by Galileo from the Greek word for vessel - (Κρατήρ a Greek vessel used to mix wine and water). Galileo built his first telescope in late 1609, and turned it to the Moon for the first time on November 30, 1609. He discovered that, contrary to general opinion at that time, the Moon was not a perfect sphere, but had both mountains and cup-like depressions, the latter of which he gave the name ''craters''. Scientific opinion as to the origin of craters swung back and forth over the ensuing centuries. The competing theories were (a) volcanic eruptions blasting holes in the Moon, (b) meteoric impact, (c) a theory known as the Welteislehre developed in Germany between the two World Wars which suggested glacial action creating the craters. Evidence collected during the Apollo Project and from unmanned spacecraft of the same period proved conclusively that meteoric impact, or impact by asteroids for larger craters, was the origin of almost all lunar craters, and by implication, most craters on other bodies as well. The formation of new craters is studied in the lunar impact monitoring program at NASA.〔(【引用サイトリンク】 title=Lunar Impacts )〕 The biggest recorded creation was caused by an impact recorded on March 17, 2013. The explosion, which was visible with the naked eye, is believed to be from an approximately 40 kg meteoroid hitting the moon with a speed of 90000 km/h. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「lunar craters」の詳細全文を読む スポンサード リンク
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