Bordeaux (AFP)

Collecting clouds during the day, locating Venus or Orion at night: physicist Blandine Pluchet advises people to leave the TV for a while to "take the time to look at the window", in an interview with AFP.

"It’s contemplation, it’s slower than what we used to watch. It’s a good time to raise your head to the sky, and discover this world that we don’t have time to look when we are always busy, "says the 41-year-old scientist who has written several popular works on the observation of day and night skies, astrophysics or quantum physics.

Confined in Deux-Sèvres, it advises to observe the clouds, "these ephemeral atmospheric phenomena" which evolve at different altitudes.

At the very top the cirrus clouds "composed of ice crystals, in the form of filaments, very fine, very delicate". Below, in good weather, "the cumulus, formed by the condensation of humidity from a mass of hot air which rises and cools, with a flat base and a cauliflower-shaped surface".

And then the stratus, "rather depressing clouds, which cover the entire sky, weigh on morale and bring the rain".

- "Like a stormy sea" -

"What can be fun, she says, especially for children, is to collect them, to look regularly over the days and to take pictures of them to become aware of their diversity".

"We can watch for rare cloud forms, like the Mamma cloud whose protrusions dot the underside, making us think of udders". Or "Asperitas, a sort of chaotic ripple like a rough sea" or Virga, with "small filaments falling from a cloud, in fact the rain which evaporates before touching the ground".

Because, with their Latin names, clouds have been classified since the 19th century, with 11 species added in 2017, some linked to human activity.

For those with windows to the west, "I invite you to observe the different stages of twilight, the changing colors until what is called blue hour, just before dark, when the first appear stars".

"At this moment, we can observe with the naked eye, to the west, the planet Venus. We cannot miss it. It is the star that shines most now after the moon. Because it is one of the closest to us and because it’s covered with clouds that reflect sunlight. Then for a few days, the crescent moon is by its side in the evening. "

"To find your way around, it's easy to download a sky map from the internet," she recommends.

"At the moment, the interesting constellations are to the southwest, towards Venus, that of Orion, one of the most beautiful in the winter sky ... with an alignment of three stars which separate two trapezoids. To the south, the constellation of the Lion, an immense crushed trapezoid, to the east, that of the Bouvier, in the shape of a kite with the star Arcturus which the Polynesians used to navigate ".

She suggests "choosing a fixed landmark, like a fireplace, a wall or a tree, looking at the stars and returning an hour later to realize that the stars, fixed in relation to each other, have moved. In fact , the earth has turned. "

With light pollution from public lighting and shops, these observations with the naked eye are difficult in large cities.

"The confinement could be the opportunity to stop a little all these lights which are not necessarily necessary. We could thus reclaim our night sky, which is a window on the universe", says the scientist.

© 2020 AFP