Earth passes through a cloud of debris from a dying comet tonight

Infrared image of the comet fragments taken by the Spitzer telescope in 2006. / NASA / JPL-Caltech / W. Reach

Science | Space

Astronomers from half the world trust to attend a great shower of shooting stars, "a great show"

Astronomers from around the world hope to see a spectacular meteor shower tonight when the Earth passes through the remains of 73P/Schwassmann-Wachmann, a comet that is disintegrating. “It could reach storm level; to be a great spectacle”, warns Josep Maria Trigo, researcher at the CSIC Institute of Space Sciences and the Institute of Space Studies of Catalonia.

In its course around the Sun, our planet passes through clouds of debris left by comets and asteroids. When these particles come into contact with the atmosphere, they cause what we popularly know as shooting stars, which are nothing more than incandescent dust. This luminous phenomenon is called a meteor, although it is called a fireball when its luminosity is greater than that of Venus, something for which the particle has to measure more than one centimeter. If any fragment is larger and reaches Earth, that rock is a meteorite.

Discovered in 1930

The comet whose debris is passing through the Earth tonight was discovered in May 1930 by Arnold Schwassmann and Arno Arthur Wachmann. Baptized as 73P/Schwassmann-Wachmann –73P for being the 73rd known periodic comet– or Schwassmann-Wachmann 3 (SW3) –for being the third discovered by the two German astronomers–, it was then calculated that its nucleus was about 1,100 meters in diameter. and that it completed an orbit around the Sun every 5.4 years. But SW3 was so dim that it was not seen again until August 1979.

In 1995, it surprised astronomers by being 600 times brighter than it was in 1990 and visible to the naked eye. It turns out that it had broken into pieces and had filled its wake with debris. Eleven years later, in May 2006, the Spitzer Space Telescope photographed SW3's cometary fragment train, then made up of almost 70 pieces, from pebbles to large rocks. "In 2022, the Earth is expected to pass close to the comet's trail, producing a remarkable meteor shower," then predicted the corresponding
NASA press release.

Today astronomers from America and Europe will look to the sky hoping to enjoy a great spectacle of nature. “We are all waiting. Not every day the remains of a dying comet cross the Earth, ”Trigo, coordinator of the Spanish Network of Fireballs and Meteorites, tells this newspaper. "Tonight," he adds, "our planet crosses not only the debris cloud left by SW3 in 1995, but also those from the 1892 and 1897 passes, which are very dense."

where to look

Although there may be meteoric activity all night, the maximum is expected in the peninsula and the Canary Islands shortly before dawn. If our planet runs into large enough comet debris, "the show will be best seen in America." An advantage is that there is a full moon or, it is the same, the Moon does not shine in the sky. The best way to enjoy this shower of stars is to get away from any urban center and have a clear western horizon, since the radiant – the point from which the shooting stars of SW3 seem to come out – is located near Arthur, the third star brightest in the sky.

Trigo and his colleagues from the Red Española de Bólidos y Meteoritos have organized a photographic contest around the shooting stars of SW3. The author of the best image of the phenomenon that reaches them accompanied by the corresponding scientific data "will be awarded with a batch of popular astronomical books",
promises the astronomer in his blog. In addition, all astrophotographers who send images to them will be cited in scientific papers stemming from tonight's meteor shower study.

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