Woe, when the mistral blows. The cold wind from the northwest is causing astronomers at the Observatoire de Haute-Provence (OHP) about 45 days a year. Not because it causes frosty temperatures. On the other hand, one can arm yourself. The problem is rather that atmospheric disturbances then abruptly worsen the observation conditions.
Normally sky gazers out there, about 100 kilometers north of Marseille, have a relatively undisturbed view of the French night sky. On a plateau, about 650 meters above the sea, four mirror telescopes. They are not very tall, they are not very modern.
And yet, one of them has revolutionized our view of the cosmos: on the 1.93-meter telescope of the OHP, the Swiss astrophysicist Michel Mayor and his former doctoral student Didier Queloz tracked down the first known planet outside the solar system nearly 51 years ago: 51 Pegasi b, recorded today in the sky maps as Dimidium.
"Someone had to do it"
"Everyone expected that there are such planets," says Matthias Steinmetz, Scientific Director at the Leibniz Institute for Astrophysics in Potsdam. "It was time to measure that too, but somebody had to do it." And that was Mayor and Queloz. For their discovery, the two were awarded on Tuesday by the Royal Swedish Academy of Sciences with half of this year's Nobel Prize for physics.
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Seen from Earth, a distant planet is extremely faint. He only reveals himself indirectly - for example, because he always pulls a bit on the star he circles around because of his mass. The fact that this star moves back and forth, can be demonstrated with a spectrograph in its light: sometimes the waves are pulled apart a bit, sometimes minimally compressed.
Seen from the earth, the light of the star periodically looks slightly different. However, Mayor and Queloz also had to show that the observed changes can not be explained only by the fact that the material of their telescope had expanded slightly in the heat of the day and shrank again during the night. "If I'm not careful, it looks like an exoplanet," says Steinmetz.
In the meantime, astronomers know more than 4000 of these distant worlds - and that is for sure just an incredible small fraction of the planets out there in the universe. Mayor and Queloz have "really opened up a new field of research," praises Heike Rauer, director of the Institute for Planetary Research at the German Aerospace Center (DLR) in Berlin. "This is a long-deserved award."
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Once, as a doctoral student, she observed comets at the OHP herself, Rauer recalls. She had to share her time at the telescope with exoplanet researchers. At that time she had found that funny: "Something crazy, that can not exist."
Today she is exploring exoplanets herself.
And she also knows how diverse these distant worlds can be. The planet that the two Swiss had discovered is a gas giant of half the mass of Jupiter, but orbiting extremely close around its star, in only one-eighth of the distance from Mercury to the Sun.
But not only such cosmic curiosities interest the exoplanet researchers. They are also looking for life-friendly places in space, for a second, third, fourth earth somewhere out there. Are we alone in space? That's a question that even four-year-olds can understand and find fascinating. It is one of the most fundamental questions in the universe.
That we are alone in space, that is still possible. Just because there are exoplanets, there does not necessarily have to be life somewhere. By all the laws of probability, it is very, very, very unlikely, if that were not the case.
We do not have to oracle anymore - we can search
Only by the call of the SPIEGEL exoplanet researcher Rauer on Wednesday learned of the honor for the two colleagues. That's because she was sitting with colleagues in a preparatory meeting for the planned European probe "Plato". From 2026 onwards, it will search for more planets in the depths of space, using a different method than Mayor and Queloz's: Instead of looking for stars that treacherously wobble, it is instead inquired whether passing planets may be shining their star's light darken for a short time.
The technical management of "Plato" lies with German researchers. But that this mission, that there is even the research subject at all, is due to Mayor and Queloz. The two Swiss have made sure that when we ask ourselves whether we are alone in space, we do not just have to oracle - we can now search.
How the world became "interesting"
James Peebles, who was honored on Wednesday with the other half of the Nobel Prize, has dealt with an equally fundamental question: Why are we even? "Jim Peebles has explained why the world as a whole has become interesting," says Hans-Walter Rix, director at the Max Planck Institute for Astronomy in Heidelberg, the SPIEGEL. Because shortly after the Big Bang, the universe had been impressively boring: "Everything was equally distributed."
The Canadian-born Peebles showed half a century ago, using computer simulations, among other things, that tiny differences in the distribution of mass in the early universe have ensured that galaxies, stars, planets exist today. Under the effect of gravity in the expanding universe, the mass clumped in a self-reinforcing process - and structure emerged where none existed before. "Everything attracts everything else," says Rix.
Today, astronomers know that a network of galaxy clusters pervades the universe, embedded in the mysterious dark matter. And also that the cosmic models do not make sense without this dark matter, Peebles has also found that out, says researcher Rix. From which particles the substance exists, which determines the fate of the cosmos, scientists do not know until today. But Peebles has helped to exclude some candidates like the neutrinos - because their mass in the universe just is not enough.
Incidentally, when Peebles comes up, fellow researchers praise not only the intellect of the scientist, but also his extraordinary personality. There is talk of an "incredibly likeable person" with "great restraint" and of "unbelievable modesty." You hear the praise of a star without airs. "If you sit in meetings, where the powerful group and the mass," says the Potsdam astrophysicist Steinmetz, "then he sits in the crowd."
And not only the award winner is top: "This is the perfect price for astrophysics," rejoices Steinmetz and builds the bridge between the cosmologist Peebles and the exoplanet researchers Mayor and Queloz. "Because he asks the question, 'Where are we from?' connects with the question: 'Are we alone?' It's a price that ranges from the biggest to the smallest. "