Nights of the stars: the sky awaits you


From August 6 to 8, the French Astronomical Association invites the general public to observe the sky, and in particular the meteor shower that illuminates the nights of August.

A corner of the countryside without surrounding light pollution, a blanket, sharp eyes and a dreamy spirit: once night has fallen, sit down and roll your eyes to enjoy one of the three Star Nights of 6, 7 and August 8. A free show hosted as every year in the middle of summer by the French Astronomical Association. Hundreds of observation sites are offered, animated by amateur astronomers. The full program is available on the association’s website, afastronomie.fr.

However, it will be necessary to hope that the sky of summer 2021 wipes away its tears a little and gives up spoiling the party: Météo-France announces for Saturday evening clouds over a very large part of the country, the South-East excepted. A little more heavenly mercy is expected Sunday night. Good news on the other hand, the moon will be discreet and its radiance will not extinguish its distant nocturnal companions: making its monthly moult from Sunday, it will be invisible or almost during these three Star Nights.

The sky chart for August 7 at 10 p.m. (T. U. + 2). Bertrand d’Armagnac / Stelvision

A little after 9:20 p.m. sunset time (Saturday at the latitude of Paris; it’s a little earlier in the east, a little later in the west) you can first admire the brightest planets, Venus, low enough on the horizon (about 10 ° above the horizon, due west); beware, the early bird will disappear below the horizon an hour later. Saturn (10 ° southeast, then up to 22 ° south towards 1:30 a.m.) and Jupiter (5 ° east-southeast at 10:30 p.m., then until 28 ° southern horizon around 3 o’clock). A simple telescope can show you the rings of one and the satellites of the other.

But you will have to wait until the end of astronomical twilight (11:38 pm this Saturday evening in Paris) to fully enjoy the show… Then look for the stars: the scintillating points of Véga, Deneb and Altaïr (they are part of the “summer triangle” “Made up of the constellations of Lyra, Cygnus and Eagle), the whitish line of the Milky Way, the spiral cloud of the Andromeda galaxy … Sky charts, which can be set by date, desired time and place, are available in particular on stelvision.com (map above).

A frantic pace

But the stars of this thirtieth anniversary of Star Nights will be the shooting stars, small dust from comets or asteroids which burn off when they enter the atmosphere. August offers us the Perseids: debris of comet Swift-Tuttle, they rush at more than 200,000 km / h and “light up” 115 km above our heads to die at some 90 km altitude. All at a frantic pace: nearly 100 shooting stars per hour during the peak, which will take place this year on the night of August 12 to 13!

The Perseids have this advantage compared to the other regular and intense rain of shooting stars that are the Quadrantids (they, visible at the beginning of January), to enter our atmosphere in August when the sky is (generally …) clear and the night temperatures mild enough to invite observation. Place glasses and telescope here: your eye will be a much better observer, because it alone “Offers a ‘wide angle’ vision which allows us to grasp the whole phenomenon”, slips the French Astronomical Association.

But while watching them (they seem to come from a point above the northwest horizon, in the constellation Perseus), remember that these spinners are not only the occasion to dream while making wishes. . “The comets and the asteroids from which they originate are the oldest celestial bodies in our Solar System. To study them is to study our history, that of the Earth and our planetary system ”, pleads the French Association of Astronomy, which recalls that the composition of comets and, to a lesser extent, of asteroids is the same as at the birth of the solar system. Watching the Perseids is a leap to the earliest ages of the world …

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