Wikipedia
thumb|right|240px|Location of Euctemon Euctemon is a lunar crater that is located in the northern part of the Moon, along the northwest rim of the crater Baillaud. To the southwest of Euctemon is the large walled plain Meton, and to the north-northeast lies the crater De Sitter. Due to its location, Euctemon appears foreshortened when viewed from the Earth.
The interior floor of this crater has been resurfaced some time following the original formation, leaving a nearly level, featureless plain surrounded by the worn outer rim. This floor is marked only by a number of tiny craterlets, and the small crater Euctemon K near the southwest inner wall. A small crater has cut through the western rim, and has joined with the main crater by a gap in its eastern rim. The two craters now share a common floor. Just to the north is another small crater, Euctemon H, that now forms a wide cleft through the rim. Along the ridge that separates Euctemon from Baillaud is perched the small crater Euctemon N.
Euctemon (, fl. 432 BC) was an Athenian astronomer. He was a contemporary of Meton and worked closely with this astronomer. Little is known of his work apart from his partnership with Meton and what is mentioned by Ptolemy. With Meton, he made a series of observations of the solstices (the points at which the sun is at greatest distance from the equator) in order to determine the length of the tropical year. Geminus and Ptolemy quote him as a source on the rising and setting of the stars. Pausanius's Description of Greece names Damon and Philogenes and Euctemon's children.
The lunar crater Euctemon is named after him.