Selenography

"Lunar Day", from the book Recreations in Astronomy by H. D. Warren D. D., 1879. This represents a historical concept of the lunar surface appearance. Robotic missions to the Moon later showed that the surface features are much more rounded due to a long history of impacts.

Selenography is the study of the surface and physical features of the Moon. Historically, the principal concern of selenographists was the mapping and naming of the lunar maria, craters, mountain ranges, and other various features. This task was largely finished when high resolution images of the near and far sides of the Moon were obtained by orbiting spacecraft during the early space era. Nevertheless, some regions of the Moon remain poorly imaged (especially near the poles) and the exact locations of many features (like crater depths) are uncertain by several kilometers. Today, selenography is considered to be a subdiscipline of selenology, which itself is most often referred to as simply "lunar science." The word selenography is derived from the Greek lunar deity Σελήνη Selene and γράφω graphō, "I write".

History

The idea that the Moon is not perfectly smooth originates to at least circa 450 BC, when Democritus asserted that the Moon's "lofty mountains and hollow valleys" were the cause of its markings.[1] However, not until the end of the 15th century AD did serious study of selenography began. Circa AD 1603, William Gilbert made the first lunar drawing based on naked-eye observation. Others soon followed, and when the telescope was invented, initial drawings of poor accuracy were made, but soon thereafter improved in tandem with optics. In the early 18th century, the librations of the Moon were measured, which revealed that more than half of the lunar surface was visible to observers on Earth. In 1750, Johann Meyer produced the first reliable set of lunar coordinates that permitted astronomers to locate lunar features.[citation needed]

Lunar mapping became systematic in 1779 when Johann Schröter began meticulous observation and measurement of lunar topography. In 1834 Johann Heinrich von Mädler published the first large cartograph (map) of the Moon, comprising 4 sheets in size, and he subsequently published The Universal Selenography.[2] All lunar measurement was based on direct observation until March 1840, when J.W. Draper, using a 5 inch reflector, produced a daguerreotype of the Moon and thus introduced photography to astronomy. At first, the images were of very poor quality, but as with the telescope 200 years earlier, their quality rapidly improved. By 1890 lunar photography had become a recognized subdiscipline of astronomy.

The 20th century witnessed more advances in selenography. In 1959, the Soviet spacecraft Luna 3 transmitted the first photographs of the far side of the Moon, giving the first view of it in history. The United States of America launched the Ranger spacecraft between 1961 and 1965 to photograph the lunar surface until the instant they impacted it, the Lunar Orbiters between 1966 and 1967 to photograph the Moon from orbit, and the Surveyors between 1966 and 1968 to photograph and softly land on the lunar surface. The Soviet Lunokhods 1 (1970) and 2 (1973) traversed almost 50 km of the lunar surface, making detailed photographs of the lunar surface. The Clementine spacecraft obtained the first nearly global cartograph (map) of the lunar topography, and also multispectral images. Successive missions transmitted photographs of increasing resolution.

Lunar Oceanus Procellarum ("Ocean of Storms")
Ancient rift valleys, rectangular structure (visible – topography – GRAIL gravity gradients) (October 1, 2014).
Ancient rift valleys, context.
Ancient rift valleys, closeup (artistic conception).
Other Languages
Afrikaans: Selenografie
Bân-lâm-gú: Goa̍t-lí-ha̍k
català: Selenografia
čeština: Selenografie
Deutsch: Selenografie
español: Selenografía
français: Sélénographie
hrvatski: Selenografija
Bahasa Indonesia: Selenografi
italiano: Selenografia
Lëtzebuergesch: Selenographie
Nederlands: Selenografie
日本語: 月理学
norsk nynorsk: Selenografi
polski: Selenografia
português: Selenografia
română: Selenografie
русский: Селенография
Simple English: Selenography
slovenčina: Selenografia
svenska: Selenografi
українська: Селенографія
中文: 月面学