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Occupation: exoplanet hunter

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Posted on 28-03-2015 at 19:59

The French astrophysicist Jean Schneider started looking for these potentially habitable planets in a time when nobody believed. Thanks to him and a handful of pioneering discoveries fall today as if it rained.

Artist's impression of the three stars of the exoplanet HD 188753 Ab (one of the stars lying down) from a hypothetical satellite of the latter (Wikipedia / CC / Nasa)

His hair is white, long, float, his eye, playful and curious like a kid, so Albert Einstein, without tongue playfully pulled. And his childhood dream has not aged:

When I was young, I watched the stars and wondered if there were people there. "

A 74 spring, Jean Schneider always looking forward to "the day when we receive a picture of their world sent by aliens."

Jean Schneider: probably this name he told you nothing but this discreet man is a figure of the forefront of the scientific community. A pioneer counting among the handful of diehards dream hunters have launched in the unlikely quest for exoplanets, potentially habitable planets, outside our solar system, sometimes "only" a few light years from us.

(The astrophycisien Jean Schneider at the Paris Observatory.
Credit: Philippe Grollier / Pasco for "Obs")

Are we alone in the universe?

It was at the end of the 1980s, returning from a mission of experts to the Brussels commission, astrophysicist at this Laboratory Universe and Theories (Lute, in Paris), philosophy and linguistics enthusiast, decided to spend on one of our great existential questions: Are we or not, alone in the universe?

Today the subject puts the Web in turmoil. Especially since we are posting all four mornings a new discovery. The latest exoplanet to have a sensation as having several characteristics similar to those of Earth, was discovered in January. Like all the others before her, she was decked out with a cryptic code-named Kepler 438-b.

Immediately, the imagination of Internet users caressing the dream of an encounter of the third kind or interstellar travel was kindled. The Krypton and other Tatooine have beautiful long populate a slew of books and movies SF, no scientist "serious" or almost here just two decades, believed in their existence. Explanation of John Schneider:

Yet it is a matter of extraordinary research, with a philosophical component, which helps reflect the different forms of life, which is plant or animal ... And I always liked to study topics that nobody cares again.

Theoretically, nothing stood gravitate to the idea that planets like those in our solar system around the billion stars in the universe, but in the absence of tangible evidence, most astronomers eventually conclude that they simply did not exist. "

Galactic Challenge

To date, 1,800 certified and 3,000 to 4,000 exoplanets have already been identified. And must, directly or indirectly, a sacred harvest of these findings to John Schneider. So much so that our national star could - who knows - outdo his American alter ego Geoffrey Marcy, in whom the "New York Times" sees a potential Nobel Prize.

For if Marcy account his list of the greatest number of exoplanets (70 percent over the first identified), Jean Schneider, who first proposed a method to flush them out. This at a time when, said the American, "look for other Earth through the cosmos smelled science fiction, mystical folklore as the power of the pyramids or telekinesis ...". "The ideas fall from heaven like that ..." relativized Jean Schneider, in all modesty. Not so simple ...

(Artist's impression of the extrasolar planet CoRo T-7b.
Credit: CC / ESO / L. Calcad was via Wikipedia)

Finding exoplanets in the infinite cosmos held the galactic challenge. For, except those with temperatures above 1,000 ° C, they do not emit light, but reflect just that of their star. And, as the closest are at several light years of our blue planet, so finding a needle in the Milky Way, and groping at that.For, to make matters worse, astrophysicists did not have to start that very few clues about the areas to which direct their telescopes.

We had the necessary instruments, telescopes were already sufficiently powerful and precise, only we do not know how to go about it. "

It was then, in 1988, John Schneider suggests using the method called "transits", "pure intellectual speculation." Explanations:

I assumed that a planet passing in front of its star would cause a change in light of this star. This would be repeated periodically, with each pass of the planet on its orbit. Also, staying trained on a portion of the cosmos, say a field comprising a thousand stars, we would be able to identify these variations, and therefore any exoplanets. "

Discoveries that are accelerating

Our man does not know, but at the same time, an American, William Borucki, has the same idea, the other side of the Atlantic.

In fact, this possibility had been mentioned in a book in the nineteenth century and again in the 1950s, but no one had planned to implement it and thought about applying for exoplanets. "

And then thunder, it is ultimately a Swiss astronomer Michel Mayor, who in 1995, the jackpot: it identifies the first extrasolar planet, 51 Pegasi b, from the observatory of Haute-Provence. Jean Schneider says

He had managed, with his student at the time, Didier Queloz, and Andrew Baranne, optician engineer to develop a spectrograph with a very high accuracy. "

If the first discoveries fell dropper for more than fifteen years, they are accelerating today thanks to increasingly powerful spectrographs. This device analyzes the stellar radiation. It allows to confirm the presence of a planet by observing tiny variations in the orbit of its star and calculate its mass from the laws of gravity.

But it is mostly shipped telescopes in space, much closer to the goal that hit.In particular Corot, launched by the CNES (National Space Research Centre) at the initiative of Jean Schneider. Since his return to Earth in 2013, all data have not yet been exploited. We can also count on the famous Kepler, sent by NASA through William Borucki. After a failure, it is now left through the cosmos and continues its harvest of promising stars.

"The cosmos is not empty"

Not only John Schneider "has a lot of good ideas," as emphasized Geoffrey Marcy, but we also owe him an online encyclopedia, the only identify all identified exoplanets. A must exchange for specialists and enthusiasts worldwide.

They are classified according to the habitability criteria. So far we mostly found gaseous stars, large, more "easy" to spot but unlikely to support life forms as we know them. But in recent months, rocky planets smaller, appeared in the eye of the instruments.

(Illustration Kepler telescope in orbit. Credit: NASA )

Some being in the "habitable zone", not too close nor too far from a star, where water, very present in the universe can exist in liquid form, which is essential to the development of life. As to observe any flora fauna, it is not for now. As Jean Schneider:

For an animal the size of an elephant on one of these planets would require a telescope the size of our solar system! "

Is of course the opportunity to go see for ourselves ... But now, even four or five light years, it is not next door.

At the current speed of our spacecraft propulsion, today it would take thousands of years to get to the nearest exoplanet us! "

And even if we would come to attain the speed of light, there remains a small problem:

The cosmos is not empty. Now, at this speed, the tiniest speck of dust becomes a projectile of great power. "

So it's not tomorrow that man walk on exoplanet .

Véronique Radier

AND, are you there?
The holy grail of exoplanet hunters would discover traces or manifestations of technological intelligence. Scientists are divided into two camps: those who argue that it is highly unlikely, if not impossible, and those who, instead, believe in it.
The famous physicist Stephen Hawking believes even unwise to signal our existence to possible extraterrestrial sending messages, as we have already done.
Geoffrey Marcy, he emphasizes that the criteria for a planet can give rise to life are many and complex: for example, where and how water is distributed there. Thus, life could develop on Earth that because water is concentrated on its surface. He added that the billions of species on Earth, the human is an exception.
"We often have the illusion that intelligence is the logical result of evolution, yet other species have not developed through their neurons, but other strategies to adapt to their environment. This even when 'they lived for very long periods, such as dinosaurs. In addition to a hundred million years, their brains had not taken a gram. "
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