The moon is the only natural satellite of the earth. There are always many secrets and mysteries associated with this celestial body, and today we will talk about one of them. At school lessons, from parents, watching educational programs, we learned in childhood that the Moon is always facing the Earth on one side, and no matter how hard we try, we will never see the second from our planet. In this article, we will examine why this is so. What is the name of the side that we do not see? How does it differ from the other side of the moon?
Meaning of the word terminator
You might now think about what the cult action movie was mentioned, but that's right. The word "terminator" has several meanings.
Firstly, this concept is present in the characterization of DNA. Terminator - a sequence of DNA nucleotides that are recognized by RNA polymerase, and a signal is received to stop the synthesis of the RNA molecule and the dissociation of the transcriptional code.
Secondly, in electronics this concept is called an energy absorber located at the end of a long line, and its resistance is equal to the wave impedance of the line.
Third, the terminator is Russian military equipment (tank).
And fourthly, the concept is used in astronomy. The terminator is a light separation line that separates the illuminated from the unlit part of the satellite (or other celestial body). This line never has a clear boundary, the dark and light parts are separated by a smooth transition. The Moon Terminator cannot be seen with its growth and aging.
Dark side of the Moon
As mentioned above, only one hemisphere of a natural satellite is always visible from the Earth. Why it happens? It's all about rotation: the moon has periods of rotation around its axis and around the Earth, they are very similar. Both last 27 days.
Nevertheless, the reverse side was photographed many times using satellites and space stations, the first was the Luna-3 AMC, which belonged to the Soviet Union. It happened in 1959, October 7th. Landing so far on the “dark” hemisphere has not been made, but Chinese scientists say that in 2018 their AWS will land there.
What does the moon look like on the other side that we cannot see from the earth? The part visible to us is covered by a very large number of seas (more than 30), there are not very many craters there. In the other hemisphere there are only two seas, the entire remaining surface is strewn with craters, because space debris most often crashes into it.
Conclusion
So, we found out that the Earth’s natural satellite, the Moon, has two hemispheres that are completely different in structure. The one that we see is smoother, there are many seas and few craters on it, and many of the craters cover the invisible part of the Moon. The article also discusses several meanings of the word "terminator", one of which relates to astronomy.