Myth 5: The moon is a perfect sphere
Although the full moon appears as a perfectly circular disc in the night sky, it is actually asymmetrical. Its crust is thicker on the far side, while unusual mass concentrations show up on the near side.
Optical observations made from the orbiting spacecraft during Apollo 11, as well as several other Apollo missions, provided very accurate locations for 31 craters, suggesting that the center of mass of the moon did not lie at the center of its sphere, but rather was slightly displaced. Further studies demonstrated that the moon bulges slightly on its Earthward side.
Myth 6: The moon contains life
Although the idea may seem preposterous today, when Apollo astronauts first headed toward the moon, there was a concern that life in some form may exist on the lunar surface. Materials and equipment to be deployed on the lunar surface were sterilized to prevent contamination from Earth. At the same time, the returning astronauts were put through time-consuming quarantine measures to prevent bringing home potentially hazardous lunar life forms.
A study of the samples from the moon revealed no trace of past or present life on the lunar surface. A careful study was made for carbon, since life on Earth is carbon-based, but scientists found only a few dozen parts per million of the element that was native to the moon, much of which had been injected by solar wind. None of the carbon appeared to come from life processes. Minerals from the moon also lacked significant traces of volatile elements. Astronauts found no sandstone, shale or other minerals that require water to form.
The surface of the moon is simply too hazardous for life to form. The airless surface lacks a substantial atmosphere to shield growing life from radiation from the sun, and temperatures swing from minus 255 degrees Fahrenheit (minus 160 degrees Celsius) to 250 F (120 C) over the course of a month.
Myth 7: The moon is a hollow spacecraft
In 1901, science-fiction writer H.G. Wells wrote "The First Men in the Moon," a novel that depicts the interior of the moon as the home of an alien species. Other science-fiction stories followed suit. Science even got in on the act, with two Soviet scientists proposing that the moon is actually a shell-like alien spacecraft.
However, the Apollo 11 mission investigated the thickness of the moon's crust, mantle and core. One of the experiments set up by astronauts was the Passive Seismic Experiment, built to detect moonquakes over the course of three weeks. Although the experiment revealed that the moon does occasionally shake, it also showed that the vibrations are less powerful than those found on Earth over the corresponding period.
If three or more seismometers detect an event, scientists can calculate its origin. This, in turn, led to a deeper understanding of the lunar layers, revealing that the moon is not hollow.
Other Apollo missions deployed more advanced seismometers that helped further scientists' understanding of the moon's composition.
Originally published on Space.com.
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