The light of the Moon has fascinated us since our appearance on Earth and helped us to orient ourselves.
The Chinese, the Indians, and the Babylonians used observations of the night star to understand the time, but also for religious ceremonies. A rabbi states in the pages of the Talmud that the Moon was created to count the days. Coming closer to the present, the one who changed people’s conception of the Moon was Galileo Galilei, who made the first drawings of the lunar surface. He discovered irregular lunar formations which he called, in his work Sidereus Nuncius, elevations and depressions with cavities and protrusions similar to those on the face of the Earth. Galileo described the great moons perfectly, only he thought that there was water there. The first map of the Moon was not drawn by Galileo but by Cesare Lagalla, a philosophy professor from Rome. The first map containing the names of the selenary formations as we know them today was drawn by Francesco Maria Grimaldi from Bologna and was published in Giovanni Riciolli’s Almagestum novum in 1651. It seems that Riciolli did not write down the names of the craters by chance.
A great admirer of Tycho Brahe, Riciolli calls the most imposing crater of the Moon, Tycho.
As important regarding the research of the lunar surface, the Soviet and American missions during the Cold War should be mentioned. Thus, the first man-made object to touch the lunar soil is Luna 2, the second Soviet mission to the Moon. The Luna 3 probe manages, in the same year 1959, to take the first photographs of the “unseen” face of the Moon. Of course, humanity’s dream of reaching the Moon is fulfilled by Apollo 11, which succeeds, in 1969, in taking the first people to walk on the Moon, in fact, the first mission with a human crew on another celestial body from outer space.
When we can observe the Moon
Returning to Earth, it must be said from the beginning that the most spectacular celestial object that you can see through a telescope is the Moon.
The explanation is simple: it is the closest star to us, hence the show of details. I have often heard the expression “It has set, so the Moon has risen!” Nothing more false in this statement.
In most cases, when it gets dark, the Moon is already in the sky, either high, to the south, at sunrise, or even at sunset. From any point on the globe, the Moon stays in the sky for 12 hours a day on average. Sunrise, also on average, 45 minutes later than the previous day.
What can be seen through the telescope?
The moon makes a complete rotation around the Earth once every 27 days and almost 8 hours. To return to the same phase, the star needs 29 days and nearly 13 hours. This is explained by the fact that in 27 days the Earth completes part of its orbit around the Sun, and after this period, the light received from the Sun does not fall at the same angle as 27 days ago. In other words, if we look south in the evening we will see the first square. We will be able to observe the same lunar phase only in 29 days, even though the Moon completes a complete rotation. Moving on to observation with the help of the telescope, although Tycho is the most prominent crater when the Moon is full, viewed through the telescope it is not the most spectacular. A little further to the southeast, you can see the Cassini crater, and to the south the imposing Archimedes.
Close to the equator, a little more to the west, the Copernicus crater appears, and on the opposite side below the equator, in the eastern hemisphere of the Moon, is the Great Fertility crater.
How and when we photograph the Moon
It is best to photograph the Moon around the two squares to capture the lunar relief. For good results, a focal length of more than 400 millimeters and a diaphragm as wide as possible must be used, which will help you obtain shorter exposure times. Do not forget that the Moon moves in its orbit at 3860 kilometers per hour, and the Earth evolves around the axis (in the same direction as the revolutionary movement of our satellite) at 1670 kilometers per hour.
Lesser known things about the Moon
In recent years, I have been reading about the settlements of the future, about lunar cities. But what does the sky look like from there? First of all, the Moon has no atmosphere. In other words, the light received from various sources (Sun, Earth, Stars) falls directly on its surface, without refraction, reflection, and dispersion. Unlike the Earth, the lights seen from the Moon are stronger and clearer, and the shadows, are longer and better defined. The first thing you notice is the deep black color of the sky. The second thing is the Earth. It must be very strange that, after you left the Earth with a shuttle and left it somewhere down, now you see it in the sky! The Earth’s disc remains almost fixed on the starry vault, shows phases like the Moon, and rotates around the axis from left to right, being able to be used as a clock.
The sun stays in the sky for 15 days, and the other 15 are at night. Sunsets and sunrises are sudden. There is no twilight, no pastel colors of dusk and sunset. The stars do not twinkle, and in the light of the full Earth, you can read without problems. The light received from the Earth in this phase is 100 times stronger than the one we receive on the ground when the Moon is Full! The Moon approaches the minimum distance from Earth (perigee) every 27 days and has a moment of maximum distance (apogee) also every 27 days. These positions are separated by only 13 and a half days. Although there are many apocalyptic news stories, the approach (or departure) of the Moon from the Earth happens every calendar month and is nothing unusual.
The “unseen face” presents higher reliefs, at least in the Northern Hemisphere the Moon presents a mountainous surface. The Moon is attracted to the Earth, we intuit this quickly. But who attracts the Moon with more force, the Earth or… the Sun? Let’s do a quick calculation. We compare the attractive force of the Earth with that of the Sun exerted on the Moon. Both forces depend on mass and distance. The mass of the Sun is 333,000 times greater than the mass of the Earth. The distance from the Sun to the Moon is 400 times greater than from us to our natural satellite. The force of attraction decreases proportionally with the square of the distance, so the force of attraction that the Sun exerts on the Moon is 400 x 400 times less than that exerted by the Earth, so it is 160,000 times smaller. Compounding the mass-distance relationship, it turns out that the Sun’s attraction force exceeds the Earth’s attraction force exerted on the Moon by 333,000/160,000=2.08, i.e. more than twice. And then why doesn’t the Moon fall on the Sun? The answer is simple: it does not fall for the same reason that the Earth does not fall on the Sun.
The Moon and the Earth form a double-planet system, and the Sun attracts the center of gravity of this system. That is, the Sun does not get involved in the internal relations of the Earth-Moon couple, but attracts the barycenter of the system, transforming through this force of attraction the rectilinear movement of the couple into a curvilinear-orbital movement around the Sun.