Eric Lagadec bears his name particularly well. A man whose last name means “good eye” or “big eye” in Breton was probably predestined to do astrophysics with telescopes. In any case, this “wink” pleases him.
Historically, astronomy started simply with our eyes. The revolution happens with Galileo in 1609 with the development of his telescope : “It allows him to see incredible things, mountains on the moon, the phases of Venus or the satellites of Jupiter” enumerates Eric Lagadec. The Pisan also becomes aware of the amazing number of stars In the universe : “Our view of the world changed completely at that time.“.
This Wednesday July 18 marks the great return of Saturn in the Breton night sky, look to the east (the planet is circled in red) – Stelvision
A telescope, “it is a light bucket, and like a bucket that fills with water when it rains, the bigger it is, the more light it can catch“explains the astrophysicist. Increasingly efficient telescopes therefore make it possible to see fainter stars : either smaller or more distant.
The James Webb space telescope allows a new understanding of the universe © AFP – Sophie RAMIS, Gal ROMA
Understand the melody of the stars
The new telescopes also significantly improve the resolution and allow you to see more details. The Breton roots of the astrophysicist go back to the time of the analogy: “With current telescopes, it’s as if we could see the bubbles of a beer on a Brest terrace from New York.“.
The image of the supermassive black hole at the center of the galaxy was made public in August 2019. This black hole is millions of times more massive than the sun © Maxppp – UPI
The improvement of imaging techniques thus enabled us to see in 2019 for the first time the giant black hole in the center of the galaxy (With l’Event Horizon Telescope). Telescopes have their fields and their specialties: “It’s like going to a concert and can only hear the note A, if you can’t see all the colors, you can’t understand the melody of the stars“, summarizes Eric Lagadec. Telescopes therefore operate in different color areas (visible, infrared, ultraviolet, microwave or X-ray) to fully understand light. To see the difference in light between the James Webb and Hubble, it’s here
and it is impressive.
10,000 galaxies in the eye of a needle
An image particularly marks the Breton. He lived in Brest in the early 90s when the Americans launched the space telescope Hubble : “The director of the telescope is entitled to 10% of the observation time and he has decided to point to an empty spot in the sky for several days”. The explanation makes you dizzy: “It’s as if you were looking through the eye of a needle stretched out at arm’s length into an empty region of the sky.“. The result is incredible: “10,000 galaxies appeared“. The image shows depth and diversity that mark generations of astrophysicists: “You can see the whole history of the universe in a very small field, it’s a splendid image that I’ve looked at I don’t know how many times“.
An emotion that came back with the first space telescope image James Webb last summer : “It was also a deep field and I thought people were seeing this image for the first time and maybe it was going to change their lives too“, is moved Eric Lagadec.
A sublime image of Saturn from the Cassini probe © Maxppp – NASA/JPL-Caltech
The astrophysicist publishes at least one image per day of the sky on his social networks. With a special tenderness for Saturn : “I particularly like the photos of the Cassini probe which allows you to see the methane lakes on some of its moons, but also obviously its rings which are the finest known structure in the universe “.
Images that make the general public dream, it is important for the astrophysicist who specifies: “Most of the images we make are not beautiful, but we have to highlight the wonders, because we are spending public money and we have to be able to share that with people and make them dream.“. More Are these gorgeous images true to life? ? In other words, if we could transport ourselves in space near these objects, would we see the same thing? It depends, explains Eric Lagadec: “When we observe in the visible, we try to make it look as close as possible to what we would see with the eye, but the James Webb telescope, for example, observes in the infrared and we are therefore obliged to apply false colors“.
“I see nebulae from my balcony”
Like me, you may have had tantrums when you were little so that your parents bought a telescope seen in the window (unsuccessfully for me). THE first price telescopes are they good instruments for observing the sky? Yes, explains Eric Lagadec who bought one for 200 euros, because he left his with his parents in Brittany: “Qwhen people came to Nice, they wanted to see the stars“. The object that remains financially accessible allows him to see beautiful things: “Saturn’s rings, the Andromeda galaxy and even some nebulae“. Doing science or marveling with a small telescope is therefore possible even if it remains a very nice gift.
The large telescope of the historic site of the Côte d’Azur observatory in Nice where Eric Lagadec works © Radio France – Thomas Biet
Eric Lagadec warns, however, before rushing into a store, you must clearly define what you want to do with : “The best telescope is the one you want to use”. It is therefore necessary above all to speak with amateurs who are often eager to share their knowledge. There are astronomy clubs all over Brittany whose list and contacts are easily accessible
.
Also note that if you want to see the international space station (ISS) pass in the sky (it circles the Earth 16 times each day), NASA has posted a small app
allowing you to know your next passages. Just choose your country then your city, then Spot The Station will tell you what time to raise your head to observe it. Depending on the position of the ISS solar panels and the weather conditions, it will be more or less visible in the sky.
The map of the sky for July 17
Saturn will begin to appear in the Breton sky, but for the rest of France, we will have to wait a few more days © Visactu
2023-07-17 05:00:06
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