The Moon, great protagonist of the memorable fiftieth anniversary that we celebrate these days, has always been fascinating and enigmatic, and has not ceased to be so after the visit of humans. And two of its most striking features are its apparent size and the fact that it always shows us the same face.
The apparent size of the Moon is identical to that of the Sun, which makes eclipses a phenomenon as spectacular as interesting from the astronomical point of view. If the apparent size of the Moon were smaller, the eclipses would be like traveling spots on the solar disk and would not allow to observe the crown of the star king so clearly, nor phenomenons as interesting as the pearls of Baily; and if it were greater, we would not miss the show by default but by excess.
As is well known, the fact that the Moon always shows us the same face is due to the fact that its rotation period is equal to that of translation: it takes the same time to turn around its axis than to go around the Land. This amazing coincidence, together with the fact that its apparent diameter is equal to that of the Sun, has given rise, throughout history, to numerous speculations. But are they true coincidences or is there any scientific explanation for the hidden face of the Moon and total eclipses? I invite my astute readers to reflect on it.
A large satellite
The Moon is the largest satellite in the Solar System in relation to the planet it orbits: it is only 49 times smaller than Earth, as we have learned in school. Bearing in mind that on its surface, gravity is one sixth of the Earth's surface (so that on the Moon an astronaut weighing 90 kilos, suit included, would only weigh 15 kilos), which of these statements is true ?:
a) The Moon is denser than Earth.
b) The moon is less dense than Earth.
c) Since the Moon was formed from a fragment of the Earth, its densities are almost equal.
Due to its much lower severity, the escape velocity on the Moon is also much lower than on Earth: only 2.4 kilometers per second. Taking advantage of the absence of atmosphere, and therefore of friction and resistance, could an astronaut commit suicide by firing in front, so that the bullet would turn around the Moon and get stuck in his back?
You might think that the escape velocity is directly proportional to gravity, but it's not exactly like that. On Earth it is 11.2 km / s and on the Moon, as we have seen, 2.4 km / s, while the lunar gravity is one sixth of the terrestrial one. From the previous data, can we deduce the formula of the escape velocity?
And, returning to the coincidences, I invite my readers to point out the ones that have called them especially the attention, inside and outside the realm of science.
Carlo Frabetti He is a writer and mathematician, a member of the New York Academy of Sciences. He has published more than 50 scientific dissemination works for adults, children and young people, among themDamn physics,Damn mathematics or The big game. He was a screenwriter The Cristal ball.
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