Ever wondered about the landscape of the Moon. Read on.
The Moon is 384,403 kilometre (238,857) miles away. It is much smaller than the Earth. The diameter is 3,474 kilometres (2,159 mi), about a quarter of that of the Earth. Consequently, the pull of gravity on the lunar surface is about 17 percent of that on the Earth’s surface. During the lunar day, the surface temperature averages 107 °C. During the lunar night, it averages −153 °C.
The Moon rates about its axis in the same time that it takes to complete an orbit about the Earth. This means that one face is permanently aligned towards the Earth. The far side was not observed until the Soviet probe Luna 3 passed behind the moon in 1959.
The geography of the moon is dominated by impact craters and ancient volcanic activity. The moon has no atmosphere, weather or recent geological processes. The surface is dominated by impact craters.
There are about half a million craters with diameters greater than 1 km on the moon. The largest crater known in the solar system is the South Pole-Aitken basin which is found on the far side, between the South Pole and equator. It is 2,240 km in diameter and 13 km deep.
Source: NASA The Clementine Mission Mosiac of the South Pole of the Moon
The highest features on the moon are found just to the north-east of South Pole-Aitken basin. One theory suggests that the mountains might have formed when debris was thrown up from the impact that produced the South Pole-Aitken crater. Similar areas of highland have been found close to other impact basins.
On the near side, the Earth based observer can see large lunar plains. The ancients, described them as maria, which is the Latin for seas. We now know that these are vast pools of solidified basaltic lava. In many cases ancient lava flows have spilled into even older impact basins. There are very few maria on the far side.
Although the Apollo missions were high profile much of the rigorous mapping of the moon using modern instrumentation took place during the lower profile Clementine mission in 1994. Clementine was a joint Strategic Defence Organisation (SDI) / NASA project. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. The Geographos observations were not made due to a malfunction in the spacecraft.
The Clementine mission found that four mountainous regions on the rim of a crater at the Moon’s north pole are in permanent sunlight. It also confirmed a view that there might be water ice in the shady depths of the polar craters. The presence of water will be invaluable for future space missions.
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