Selenography
The Selenografie, dt and lunar mapping, is associated with the moon analogue of geography. The word is from the Greek words for moon ( Σελήνη, Selene ) and draw ( γραφειν, grafeïn, drawing, writing ) put together.
On the other hand, the measurement of the moon and its gravitational field - referred to as Selenodäsie - similar to geodesy.
Latitudes and longitudes
The mapping of lunar structures is usually carried out in the coordinate system selenografischer widths and lengths that are defined similarly to latitude and longitude on Earth: The coordinate axis passes through the two rotation poles of the moon, to the earth satellite rotates in 27.3 days, while the earth always faces the same side. Perpendicular to the axis of rotation passes through the center of the moon 's equatorial plane, and parallel to the equator of the moon selenographic latitude. You are circles that are getting smaller towards the poles. Through both poles are perpendicular to the equator, the meridians, great circles of equal length selenografischer. The Prime Meridian is geared to the middle towards the Earth. So we see the intersection of the equator and the prime meridian moon about the middle of the moon in the sinus Medii - up to a few degrees deviation, the so-called libration.
After the astronautical orientation is on the moon East, the direction in which the sun rises to an observer on the moon ( astronaut). With the waxing moon, the illuminated side gradually migrates from the right ( east ) to left ( west) on the lunar disc.
For example, the 93 km wide crater Copernicus is 9 ° 42 'north latitude and 20 ° 06 ' west longitude. To an observer in the northern hemisphere of the earth he is so " left above" the moon center. It was named in 1935 by the International Astronomical Union ( IAU ) to the Polish- German astronomer and canon Nicolaus Copernicus ( 1473-1543 ).
The longitude of the day - night terminator ( terminator) on the on the moon just as the sun rises, selenografische Colongitude is called. They count as angular distance from the prime meridian of the moon in the west to 360 degrees - in contrast to the usual length specification, each 180 degrees east and west is one of the prime meridian. The Colongitude is therefore zero ( or 360 ° ) with increasing Crescent, 90 ° at full moon ( Sunrise on the western edge of the moon ). The waning crescent corresponds to the Colongitude 180 °, the new moon 270 degrees. A related counting is the new moon, new moon since the elapsed time in days.
Height information
To the absolute height of lunar mountains are arbitrary, since a natural zero point corresponding to the sea level does not exist on the earth in the case of the moon. Height data are therefore derived from a lunar radius also arbitrarily fixed. According to different determinations in previous years, the normal height of the Clementine mission of 1737.4 km is used today. This amount is also based on the normal from the Lunar Orbiter Laser Altimeter ( LOLA ), the height measurement instrument aboard the Lunar Reconnaissance Orbiter, supplied data.
Moon Greeting Cards
Classic Moon cards are limited to compare with maps of the Earth. They show the Earth's satellite from a great distance in that perspective, as we see it from Earth through a telescope: a gray-yellow ball with prominent dark " seas" and bright crater areas. The areas at the edge of the moon appear to be strongly reduced because of the grazing line of sight in the radial direction. This projection is called orthographic azimuthal. Due to the strong distortion at the edge maps ( of the earth ) are rare with this property, but in lunar and planetary maps, the viewer usually wants a similar impression as to the telescope.
Newer, photographic lunar maps are usually composed of several photographs joined together " Photo Mosaics ". Lighting effects can be mitigated with image processing and it is ensured that the direction of the shadow cast is the same for all relief structures. Through the use of space probes and the mapping of the far side of the moon is possible.
The first telescopic moon sketch comes from Galileo 1610. Relatively precise lunar maps already recorded Francesco Maria Grimaldi and Giovanni Riccioli 1651st They contained numerous names of craters and other formations that have been used by later Selenografen mostly. Geminianus Montanari 1662 for the first time made use of a micrometer for fine calibration of lunar craters. A fairly accurate map of the moon was out in 1680 the elder Giovanni Domenico Cassini.
Highly detailed maps are due chiefly by Johannes Hevelius and Tobias Mayer ( 1723-62 ). The latter appeared in 1775 with 20.3 cm in diameter and contained 24 precisely measured and kartometrische 63 points. Later Mayer's detailed drawings was a verfertigte therefrom, published 35 cm overall map. Began in 1784, who later became famous autodidact Hieronymus Schröter to map its Selenotopografischen fragments that appeared in Bremen and Göttingen in 1791 and 1802.
Lunar atlases
A lunar atlas is - in correspondence with an atlas of the earth's surface - a systematic scale cartographic documentation of the surface of the moon in book form.
The first subscribed moon atlases from the 18th century ( Selenografie by Hieronymus Schröter and others). Wilhelm Beer and Johann Heinrich Mädler gave in 1837 the first lunar atlas out, which covered the entire visible lunar half. Published in 1878 Johann Friedrich Julius Schmidt the most accurate map of the moon of the 19th century based on the work of the surveyors Wilhelm Lohrmann; they had 1.95 m in diameter and shows 33,000 craters. On a 3.5m map ( 1:1 million ) Philipp Fauth worked from 1884 to 1940 and published in 1936 parts of it. But already in 1880 the photographic mapping began to enforce and reached its first peak in 1894 in the Paris Systematic Moon Atlas ( Loewy & Puiseux ). It included 24 pairs of large format photographs - each in the evening and the morning light to show the shadows of the craters in both directions. Later, the Mount Wilson Observatory published a more accurate atlas.
Even for purposes of space travel published in 1960 Gerard Kuiper in the U.S. a photographic lunar atlas, which was composed of 280 images of Lick, McDonald and Yerkes Observatory and Mount Wilson and Pic du Midi. During the first atlas of the moon back in 1961 appeared under the title Atlas of the other side of the moon, should Kuipers work to a layer map in scale 1:1 million (equivalent to 3.5 m in diameter ) to be revised, that is, with the resolution some 100 meters. Soon after, however, the mapping started by the five Lunar Orbiter Moon probes of the series from 1966 to 1968, which now included the moon back. More lunar orbiter of the following decades, the Mondkartografie further refined esp. the Clementine and Lunar Prospector missions of the 1990s. Regional you already know now details of the moon structures in the meter range.
Some examples of recent atlases are:
- John E. Westfall: Atlas of the lunar terminator. Cambridge Univ. Press, Cambridge, 2001, ISBN 0-521-59002-7
- Siew Meng Chong ( et al. ): Photographic atlas of the moon. Cambridge Univ. Press, Cambridge, 2002, ISBN 0-521-81392-1
- Ben Bussey and Paul Spudis: The Clementine atlas of the moon. Cambridge Univ. Press, Cambridge, 2003, ISBN 0-521-81528-2
- Antonin Rükl: Atlas of the moon. Sky Publ. , Cambridge 2007, ISBN 1-931559-07-4
Systematic Selenografie
The presence of solid fundamentals first suggested in the 19th century on numerous astronomers to investigate changes on the moon. Until the 1960s, was still far from clear whether the moon still active tectonics and volcanism exists.
Individual researchers were able to detect such changes at the telescope, but only on a small scale. They are called Lunar Transient Phenomena. Around 1959 it was reported by the Russian astronomer Nikolai Kozyrev on gas clouds in the crater Alphonsus, whom he had been classified as a possible volcanic object to the photographic patterns.
Other long series of observations were made in other lunar craters.
Photographic such analyzes are hardly successful because the symptoms - where, of course, some astronomers doubt - can only be observed in the short term. As a basis for systematic studies of surface structures and their formation regions are atlases as that of the Lunar Orbiter, however, indispensable.