Astronomers from around the world are hoping to see a spectacular meteor shower tonight, 30 May, when the Earth passes through the remains of 73P/Schwassmann-Wachmann, a comet that is disintegrating. “It could reach storm level; and be a great spectacle”, said 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 centimetre. If any fragment is larger and reaches Earth, that rock is a meteorite.
The comet whose debris is passing the Earth tonight was discovered in May 1930 by Arnold Schwassmann and Arno Arthur Wachmann. Christened 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 metres 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," a NASA press release predicted at the time .
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 do the remains of a dying comet cross the Earth,” Trigo, a coordinator of the Spanish Network of Fireballs and Meteorites, told this newspaper.
Although there may be meteoric activity all night, the maximum is expected on the Spanish mainland and the Canary Islands shortly before dawn. If our planet runs into large enough comet debris, "the show will be best seen in America."
The best way to enjoy this shower of shooting stars is to get away from any urban areas and have a clear view of the western horizon, since the radiant – the point from which the shooting stars of SW3 seem to come out – is located near the third-brightest star in the night sky.