Moon's movements - Eclipses

The Moon does two basic movements:

1. Rotation on its axis. The rotation is completed in 27,3 days.
2. Rotation around the Earth with a period of 29,5 days and the mean distance from Earth is 384.000Km.

Because the time that the Moon needs to complete these two rotations is almost the same, the Moon's movement around our planet is synchronous. That is why Moon always keeps the same face turned toward the Earth.

If the Earth comes in between Moon and Sun, then that phenomenon is called Lunar Eclipse. Similarly, if the Moon comes in between Sun and our planet, then we have a Solar Eclipse. An eclipse can be partial or complete.

A complete solar eclipse has scientific interest because the solar disk has exactly the same size as the lunar disk (as observed from the Earth, of course). Because of that scientists or even amateur astronomers, have the opportunity to study the solar corona easily.

We would expect that for every rotation of the Moon around the Earth, we would observe one Sun eclipse and one Moon eclipse. That doesn't happen, because of the low inclination of the Moon's orbital plane towards the Earth's orbital plane (ecliptic).

Moon's origin

There are many theories describing Moon's formation. The most known theories are the four that follow:

(A) Firstly, the Moon was an independent planet, which was later captured from the Earth's gravitational field. There are some arguments that support this theory, but statistically that event is impossible to take place, because Moon is too massive to be Earth's satellite.

(B) Earth and Moon formed a fluid planet, that rotated around the Sun. As the time passed the heavy elements were concentrated in the core and the light elements at the surface. Because of the rotation, the instability increased. This resulted to the lengthening of the planet, until two different celestial bodies were created. Today, that theory is considered improbable.

(C) Earth and Moon were created independently each one in different areas, by the same nebula (as the other planets), but from different cores. The weak point of this theory is the different composition of the two bodies.

(D) Earth collided with another planet, which had the size of Mars. From that collision, a part of that planet formed the moon, which was captured from the Earth's gravitational field. That theory is the most prevailing, according to data based on the Lunar Prospector mission and the Apollo manned missions to our satellite's surface.

Surface and the Chemical Composition

The most common features of the Moon's surface are the craters, which they were formed at the past, as various sized meteorites were hitting on the surface. Until today, we have mapped more than 30.000 craters with diameter from one to three hundred kilometers. The greatest crater - gathering is at the dark side of our natural satellite. In addition, at the moon we can observe mountains and mountain chains. Those mountains reveal vigorous geological activity in the past. The highest peak belongs to the mountain Leibniz with an altitude of 8.000 Km. In the visible side of the Moon we can observe big, flat areas, which are called "Mares" (seas). These dark areas on the Moon are covered with basaltic lava, a fact that supports our suspicions for past volcanic activity. Finally, we have to remark that the Moon isn't seismic calm, but low-magnitude quakes are detected on the surface as well as in bigger depths.

The chemical formation of the Moon's surface presents similarities with the surface of the Earth. The last investigations didn't found any proof of any life form, something that was actually expected.

The most interesting theory supports that ice exists on the two poles of the Moon. The last missions to the Moon provided some clues for that. Specifically, the reflection characteristics of radio waves from the polar surface of the Moon are similar to the radio reflection characteristics on ice, as they were measured by Clementine. Those signs were the one's that helped human interest on the Moon, grow again. In addition, the Lunar Prospector mission, detected great amounts of hydrogen at the Moon's Poles. We can suppose that this hydrogen actually belongs to water ice, but also it can be due to the absorption of the solar wind by the Moon's ground. Although the new measurements strengthen our suspicions for the existence of ice on the Moon, they don't prove it. So, that subject still remains unanswered. We hope that LunarSAT will give some answers…

Why Explore the Moon?

The confirmation of the existence of ice on our natural satellite would be a discovery of great value. It can give the priming for planning a project that foresees the establishment of a permanent human colony on the Moon. A base on Moon could be used for the accomplishment of many scientific experiments, would allow the exploitation of mineral resources of Moon and would attract many creative commercial applications. Also the experience that is going to be obtained from that attempt would help for the further exploration of our Solar System. Obviously, the developed technology could be used for a manned mission to Mars. But the existence of water is essential for the achievement of all that we referred to, previously.