Total solar eclipse: keys for a rare but predictable astronomical phenomenon

Tomorrow, at dusk, there will be a total solar eclipse, an event of great scientific, social and cultural importance. Beatríz Garcia, CONICET researcher, describes it.

The Moon will pass between the Sun and the Earth producing a total solar eclipse tomorrow at dusk. This phenomenon, which millions of people will be able to observe, will cross South America from Chile up to Buenos Aires.

Beatriz García, independent researcher of the National Scientific and Technical Research Council (CONICET), works at the ‘Technology in Detection and Astroparticles Institute’ (ITEDA). “The solar eclipse is a phenomenon that occurs when the Sun, the Earth and the Moon are aligned and the latter is interposed between the other two bodies. Because the apparent diameter of the Moon is like the apparent diameter of the Sun –the Sun is 400 times larger than the Moon but it’s 400 times farther– the lunar disk covers the entire star,” she describes.

Eclipses are events linked to “celestial mechanics”, a branch of astronomy that analyses the movement of the stars under the effect of gravitation, so the equations that explain the movements of celestial bodies subjected to this force allow us to calculate the exact movements of the future or past eclipses. This makes it possible for us to predict exactly the time they occur and the duration, maximum point and its end.

”In general, there are two solar and lunar eclipses per year. The lunar eclipses can be seen from all parts of the planet in which the full Moon is visible. This means that they occur at night, when the Moon passes through the cone of shadow projected by the Earth. But solar eclipses are visible in narrow stripes on the surface of the Earth, and as this one rotates, the total coverage also moves from west to east so that is why it can be seen from different parts of the territory. The last total eclipse that was seen in Argentina was on November 13th, 2010 in El Calafate, but that occurred for a very short time, also at sunset. The following one will be on December 14th 2020 at noon and will be visible from Patagonia,” says the researcher.

Tomorrow at dusk, the Moon will cover the Sun completely approximately for two minutes, darkening a strip of 140 kilometers on the earth. In the strip of the whole, the temperature will drop by about four degrees. Several activities were organized in different parts of the country so as to observe the event in a safe way because the damage caused by looking at it directly is irreparable. “A total solar eclipse is a shocking astronomical event for people to experiment: eclipses have always astonished people. Now, these phenomena are not inexplicable, they are predictable thanks to the development of human knowledge and the discovery of the laws that govern the Universe. It is positive to promote this type of events so that people can participate without damaging their eyesight,” the researcher concludes.


By Leo Fernández – CCT CONICET Mendoza