Total Solar Eclipse: five curiosities and fascinating aspects
From the ancient Antikythera mechanism to the future of total eclipses, five keys to better understand this astronomical phenomenon
PalmaAny major event, such as the total solar eclipse on August 12, is surrounded by fascinating aspects and curiosities. With what artifacts were these astronomical phenomena predicted in ancient times? What do you miss if you are not in a zone of totality? Will there be eclipses someday?
The "computer" that predicted eclipses 2,000 years ago
The Antikythera mechanism, built in Greece in the mid-2nd century BC, is the oldest surviving portable astronomical calculator. Made of bronze, it was used to predict eclipses, maintain an accurate calendar, and calculate the dates of six Greek games, such as those in Olympia.
This type of analog computer was recovered from the Aegean Sea in 1900, among the remains of a shipwreck, and is preserved in 82 fragments. It was not until this century that the operation of the mechanism, of which reproductions have been made, could be deciphered.
The original would consist of a wooden box 33 centimeters high and 18 wide with two dials, one for the zodiac and another for the calendar. A side crank set in motion about thirty gears on ten axes that operate two pointers (Sun and Moon) to fix the position of these celestial bodies with respect to the Earth each day of the year.
Preserved at the National Archaeological Museum of Athens, the artifact is, without detracting from Indiana Jones, the protagonist of the latest installment of the saga: The Dial of Destiny (2023), in which the most intrepid archaeologist must assemble the pieces of the "Archimedes dial", inspired by the Antikythera mechanism.
Why is 99.9% not 100%?
Approximations are not enough when it comes to a Solar eclipse. Although it is always a fascinating spectacle, a mere 0.1% makes a big difference: the difference between partial and total.
Only when the Moon covers the entire Sun does a whitish halo appear around it, the outer atmosphere, which is called the corona. If the eclipse is partial, even at 99.9%, the still visible part of sunlight is thousands of times brighter than the corona and is not seen.
When the Sun plunges totally into blackness, there is a very abrupt decrease in light, like a very late dusk, almost night, accompanied by a sharp drop in temperature and changes in the wind.
Furthermore, there are effects that occur just before totality and are reserved for 100% eclipses, such as the diamond ring, caused by the last ray of Sun, and Baily's beads, points that emerge on the edge of our satellite due to light passing between lunar mountains.
Long astronomical night
Although August 12th is the eclipse's main event, it will be a long night for sky enthusiasts, because when darkness falls, one of the most anticipated phenomena of every summer will begin, the Perseid meteor shower, which will reach its peak activity.
On a new moon night, dark enough to facilitate observation, shooting stars will begin to cross the sky and this year it will be, according to NASA's website, "one of the best meteor showers in the Northern Hemisphere".
Inclusive eclipse
Is an eclipse an essentially visual experience? The answer is no. In a kind of synesthesia game, visually impaired people will be able to experience this phenomenon through sound, thanks to the Inclusive Eclipse project of the Institute of Space Sciences (ICE-CSIC).
Light will become sound with devices called LightSound, slightly larger than a mobile phone, which transform variations in light changes into sound in real time.
Bright sunlight starts as a high flute note, and as the Moon covers the star, the sound descends to a low clarinet note before disappearing completely during totality, thus reproducing the entire process, according to the Spanish National Research Council (CSIC).
Total eclipses, expiration date?
"We live in a privileged period in the history of the solar system". In the very distant past, total eclipses were even longer than they are today, but our descendants, in about 600 million years, will no longer be able to see any, explains to EFE the president of the scientific commission of the Eclipse Trio and director of the National Astronomical Observatory, Rafael Bachiller.
The Moon is currently moving away from the Earth at an average rate of about 3.8 centimeters per year, "a very slow movement - the width of two fingers each year - but constant on an astronomical scale" and, as the distance increases, the lunar disc appears slightly smaller in our sky.