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People are preparing to observe the stars with a telescope, in the north of France. Photo of illustration.to AFP PHOTO / PHILIPPE HUGUEN

The Perseid season offers a beautiful night show: a large number of shooting stars will be visible to the naked eye in the night of August 12 to 13, 2019.

From the same swarm, the Perseids, these shooting stars will be many to illuminate the sky: between 100 and 140 per hour. " In truth, if you already see five in half an hour, it will be exceptional, " nuance Philippe Henarejos, editor in chief of Sky and Space .

The peak of activity will occur around 2 am (Universal Time), or 4 hours for France. If the prospect of getting up so early can put off, it is still possible to go out to observe the sky the next nights: the Perseids will still be intense and will end in mid-August.

Only obstacle to this spectacle: the bottom of the sky will be cleared by the reverberation of the Moon . " This phase is not the most favorable to the appreciation of shooting stars, confirms Philippe Henarejos . This is called a gibbous moon : not quite round but already very powerful in its light. "

Remains of the Swift-Tuttle Comet

Shooting stars are celestial debris. In the case of the Perseids, these are those of the comet Swift-Tuttle, a mass of ice and rock whose path passes close to the Sun. This proximity melts the ice and releases thousands of small particles that, approaching the Earth, collide with the atmosphere at a speed of 60km / second. The front part becomes incandescent and bright, leaving behind a shimmering trail.

" The biggest, the size of a tennis ball, are brighter than Venus. But some are the size of a grain of sand and we have the fleeting impression of a line of light in the night, less than a second, "continues Philippe Henarejos.

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Because of their small size, it is impossible to predict the trajectory of shooting stars, but there is no risk of collision with the Earth. They disintegrate completely during their fall. The rare celestial debris that researchers are studying are meteorites, pieces of asteroids.

Catch up session

Those who will not have the chance to admire the Perseids will be reassured: another swarm of shooting stars, this time more discreet, will illuminate the sky at the end of the month. The Delta aquarids of the South, near the constellation of Aquarius, are indeed slower - of the order of 38 km / h - but will benefit from more darkness.

The end of the summer will not mark the end of the shooting stars since the most spectacular passage will take place in November, with the swarm of shooting stars of the Leonids.

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