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Lifting our heads heavenward has always been one of the favorite activities of the human race. There are countless phenomena among the stars that intrigue us and which we have studied over the years to better understand the laws of the universe. One of the most fascinating phenomena is the lunar eclipse, which has always excited even those who are not experts in the field of celestial bodies. Like the solar eclipse, our satellite’s eclipse is an optical-astronomical effect in which the shadow of the Earth completely or partially obscures the Moon when it is illuminated by the Sun and crosses the nodal axis during the full moon phase.
Consequently, when we are dealing with a lunar eclipse, the moon itself is in the “full” phase with the order of the sun, earth, moon in order. During this long-awaited event, their distances from one another create a much larger, conical shadow of the Moon, accompanied by a wider cone, the so-called a penumbra cone in which only some of the sun’s rays are intercepted by the Earth. These two cones are especially important as they determine the type of eclipse: penumbral, partial or total.
Lunar Eclipse: How It Happens
For any lunar eclipse to occur, certain basic conditions must be met. There are three single events that together give life to one of the most beautiful spectacles a hemispherical canopy can offer us: the Sun, Earth, and Moon must be aligned, the Moon must be full, and it must cross part of the projected shadow of the Earth.
As we said, when this happens, the appropriate distances between the three celestial bodies allow for the creation of a cone-shaped shadow that is introduced by the interposition of the Earth. The amplitude of the cone, greater than that of the entire Moon, together with the amplitude of the penumbra cone causes some of the sun’s rays to be captured by our planet. We will understand that different types of lunar eclipses depend entirely on the movement of the Moon, which determines whether a total lunar eclipse, a partial eclipse, or a penumbral lunar eclipse occurs if the Moon is completely or partially in a cone of darkness.
Then we will learn the characteristics of these three astronomical events, their effects and duration. Before going any further, however, it should be noted that these are not frequent optical phenomena, as the orbit of the Moon’s rotation has a different slope than that of the Earth, about 5 ° 9 ′, and if they were correct, we would witness a solar eclipse every lunar month when the Moon there is a new moon phase, called a new moon, and a lunar eclipse when it is full.
Total Lunar Eclipse
In the scientific literature, a total lunar eclipse is when the moon passes completely through the shadow of the earth. This means that the satellite first passes through the penumbra, then further through the shadow, and finally, after exiting it, passes through the penumbral belt again. In particular, it is during this eclipse that the Red Moon phenomenon can occur. The celestial body, beloved by the Hellenic poet Sappho, takes on a characteristic reddish color due to partial darkening before entering the shadow and when leaving it, and the refraction of sunlight passing through the Earth’s atmosphere.
The same rays that are partially reflected from the surface of our planet and that the Earth sends back to the Moon. According to astronomical sources and evidence, this is the most observed lunar eclipse in history, and one that was absolutely beautiful in 2015. The eclipse that took place on September 28 of the same year was not called “Blood Moon” by accident due to its intense red color.
Not only that, we know that the last total lunar eclipse occurred on January 21, 2019 at 05:12 am and the next will occur on May 16, 2022 at 04:11 am (maximum darkness). The next total lunar eclipse seen in Italy will occur on December 31, 2028, and the lunar eclipse of July 27, 2018 is known to be the longest in this century, with a record maximum duration of one hour and 43 minutes. As for the duration of total lunar eclipses, they can last up to 100 minutes on average and are total for all affected sites – except for the transition points.
To clarify this, we must consider that our satellite crosses the shadow cone at a speed that results from the Moon’s rotation, which is much slower than the Earth’s rotation speed, which determines the duration of solar eclipses. At this time, we will see that the Moon begins to eclipse immediately black; in fact, the color is red, but it cannot be seen with the naked eye, because the part that is still illuminated reflects the light towards us: the glow prevents us from directly seeing the reddish color, which will gradually begin to appear as the glow fades from because of darkening. The same principle applies to electronic devices as cameras are sensitive to light and tend to sharpen the brightest image.
Partial Lunar Eclipse
A partial lunar eclipse, as opposed to a total lunar eclipse, can occur in our skies when the Moon is not close enough to the ecliptic to pass through the entire shadow of the Earth. In this case it is only partially covered, showing the typical hawk profile. For this reason, a partial lunar eclipse is of less scientific importance than a total lunar eclipse, especially for amateur astronomers who are usually not astronomically qualified but like to study and observe astronomical phenomena.
The above-mentioned lunar eclipse with a red moon is more popular among amateurs, which gives the possibility of taking pictures or video camera shots of the Moon with an obviously unusual appearance and color. One of the most famous partial lunar eclipses, also visible in Italy, is the one on September 7, 2006, during which it was possible to observe the shadow exiting only after the moon rises. There is also the one always visible from Italy that performed on the night of August 16-17, 2008. The more recent one is on December 31, 2009, which was almost like a total penumbral eclipse with only a short phase of a partial shadow eclipse.
Penumbral Lunar Eclipse
We have a penumbral lunar eclipse to close. It occurs when the Moon passes only through the Earth’s penumbra, not being covered by a shadow. This particular phenomenon, from a scientific and visual point of view, is much less conspicuous than the previous ones, although it has its own charm. In some cases, only a small part of the shadow can be seen, provided however that the Moon is completely in the penumbra: this is called partial penumbral eclipse.
As with shadow eclipses, penumbral declination is related to magnitude, or magnitude. The last total penumbral eclipse was recorded on February 9, 2009, and it is now the last total penumbral eclipse in recent years. From that date, all subsequent eclipses will be partial, until February 20, 2027, when another total penumbral eclipse will take place, also visible from Italy. The last partial penumbral eclipse occurred on July 7, 2009, but could not be observed from Italy.
Duration and Effects of Lunar Eclipses
Even if you are not an expert in astronomy, you know that the planets periodically return to the same positions. That said, it is inevitable that lunar eclipses, like solar eclipses, also occur cyclically. This periodic cycle was already discovered and theorized by Mesopotamian astronomers about 2,500 years ago and is known as the Saros cycle. Its duration is 6,585 days, which is roughly 18 years, at the end of which the same lunar and solar eclipses repeat themselves.
According to research, Saros has 29 lunar eclipses and 41 solar eclipses. Not only that, considering that the Earth rotates 120 degrees in 8 hours, the same eclipse will be repeated elsewhere at the end of each cycle. During total eclipses, the Moon continues to receive all reflected light. The sun’s rays as they pass through the Earth’s atmosphere are actually deflected by refraction and reach our satellite, giving it a color that has been observed to change in one eclipse. It can range from dark copper red to orange red, as well as other shades including brown, blue, and dark green.
The colors reflected by the Moon, in some cases, are also due to a specific area of the Earth that reflects light, perhaps because it is an area rich in water, such as oceans and forests, that impart unique chromatism to a celestial body “conquered” by man in 1969.
