Mare Orientale

Mare Orientale /ɔːriɛnˈteɪliː/ (Latin orientāle, the "eastern sea") is a lunar mare. It is located on the western border of the near side and far side of the Moon,^[2] and is difficult to see from an Earthbound perspective. Images from spacecraft have revealed it to be one of the most striking large scale lunar features, resembling a target ring bullseye.

Geology

During the 1960s, rectified images of Mare Orientale by

Located at the antipode of Mare Orientale is Mare Marginis.

A

Discovery and name

Mare Orientale is difficult to observe from Earth, as it lies at the extreme western edge of the near side. All that can be seen are the rough mountain ranges—the Montes Rook and the Montes Cordillera—and some glimpses of the dark mare material beyond them.^[12] However, the Moon's libration means that on rare occasions Mare Orientale is turned slightly more toward the Earth, and becomes a little more discernible.^[13]

Although various astronomers had observed hints of the mare, it was first fully described by the German astronomer Julius Franz in his 1906 book Der Mond ("The Moon"). Franz also gave the mare its name, the "Eastern Sea", as it was located on what the convention at the time considered was the eastern side of the Moon as viewed from Earth,^[14] though it is the western side as viewed by an astronaut walking on the Moon. In 1961, however, the International Astronomical Union adopted the astronautic convention for East and West on the Moon and this limb became the western edge.^[13]

The first detailed study of the Mare Orientale was by Hugh Percy Wilkins, who called it "Lunar Mare X".^[15] Franz's discoveries were not well known,^[15] and in the 1976 edition of his book Guide to the Moon, Patrick Moore claims that he and Wilkins discovered and named Mare Orientale in 1946. However, Moore credits Franz as discoverer in his 2009 Yearbook of Astronomy (p. 133-135).

Gallery

• 
  Topographic map
• 
  Gravity map based on

  GRAIL
• 
  Albedo mosaic of Clementine images
• 
  2010 photomosaic by Lunar Reconnaissance Orbiter
• 
  Photograph from Earth at full moon with Mare Orientale marked on the limb
• 
  Dome-shaped hills at the southern edge of Mare Orientale Basin, possibly formed by lava flows.
• 
  Apollo 17 photographed eastern Mare Orientale in the faint light of earthshine.

See also

• Volcanism on the Moon

References