The author is an astronomer, science communicator and professor of science education at UQAM.
Astronomy enthusiasts from Quebec, the eastern half of the North American continent and all of South America will have the chance to observe a rare total lunar eclipse on the night of May 15 to 16. . Recall that a lunar eclipse occurs when the Moon, in its orbital course around the Earth, crosses the shadow cone that our planet projects into space behind it.
The eclipse will begin around 9:33 p.m. on May 15, when the Moon enters Earth’s penumbra, but the first visible changes in the Moon’s appearance will not become apparent until 10 p.m. 29, when the Moon will enter the terrestrial shadow.
For one hour, the slightly curved silhouette of our planet will move forward on the lunar disk before it takes on a dark red hue, starting at 11:30 p.m., when the total eclipse begins. It is not until 12:55 a.m. on May 16 that the Moon will begin to emerge from its shadow; an hour later, at 1:55 a.m., the Moon will be completely out of Earth’s shadow and the eclipse will then be over.
It is important to remember that the observation of a lunar eclipse presents no danger to the eyes and can even be followed through binoculars or a small telescope. Solar eclipses can be dangerous to observe without an adequate filter…
The most impressive moment of the May lunar eclipse will begin around 11:15 p.m., about fifteen minutes before the totality phase. The majority of the lunar disk will then be immersed in the shadow of the Earth and, fifteen minutes later, the Moon will take on a spectacular red hue.
The red color of the eclipsed Moon comes from the fact that the only sunlight that reaches our satellite at this precise moment must first pass through the Earth’s atmosphere, where it is refracted. It is as if the Moon were then illuminated by all the sunrises and sunsets of the world at the same time. The more dust or cloud there is in the Earth’s atmosphere at the time of the eclipse, the darker and redder the Moon will appear.
Those who saw the lunar eclipse of December 9, 1992 will recall that at the time of totality, the Moon darkened to the point where it was barely visible to the naked eye. A few months earlier, millions of tons of gas and ash had been spewed into the Earth’s atmosphere by the eruption of Mount Pinatubo in the Philippines. This debris blocked most of the sunlight that should have reached the Moon, resulting in an abnormally dark eclipse.
The influence of volcanic eruptions on the appearance of lunar eclipses has also enabled a team of paleoclimatologists from the University of Geneva to precisely date a series of volcanic eruptions which caused a decrease of at least one degree of average temperatures on Earth at the beginning of the XIIand century. Researchers have discovered in an Old English manuscript a reference to the lunar eclipse of May 5, 1110, which was said to have been unusually dark. This date is consistent with at least one major eruption that occurred around the year 1108, which corroborates other data from ice core analysis and would explain the general drop in temperatures at that time.
Lunar eclipses have also played a role in history. At the end of June 1503, Christopher Columbus ran aground with his ships on the beaches of Jamaica and, for a few months, had to live on the help brought to him by the inhabitants of the island. But these, at the end of their patience, threatened to push the sailor and his men back to sea. Cacique of the island and threatens to steal the Moon from the sky if his crew does not continue to be supplied.
Retiring to his cabin to make incantations, Columbus waited until the eclipse had struck the inhabitants of the island with amazement before promising to return the Moon to them in exchange for the resumption of supplies. The American author Mark Twain will resort to the same process, this time using a total eclipse of the Sun, to allow the protagonist of his novel A Connecticut Yankee in King Arthur’s Court, published in 1889, to escape the stake. Of course, who doesn’t remember Tintin, Hergé’s character, who gets out of a bad situation in a similar way in the album The Temple of the Sunfirst published as a serial between 1946 and 1948?
Next meeting of Quebecers with a lunar eclipse? No later than next November 8, at the end of the night, after which it will be necessary to wait until the night of March 14 to 15, 2025 to witness such a spectacle again.