Exoplanets: The “impossible planet” observed by two Nobel Prize winners | United States

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Nobel laureates Michel Mayor (l) and Didier Queloz at the European Space Agency Center in Villafranca del Castillo.Julien rojas

In recent months, astronomers Michel Mayor, 78, and Didier Queloz, 55, have been observing an “impossible planet”. It’s called 55 Cancri e and it’s a little bigger than the Earth. It’s so strange that it shouldn’t exist. But here it is: 40 light years from Earth, orbiting a twin star from the Sun. On this planet, one hemisphere always faces the Sun. The surface is over 2000 ° C and the dark side is 1300 ° C. It is likely that the entire planet is covered with molten rock. This is what astronomers call a lava world.

“It is the only planet of this type that we can observe,” Queloz told EL PAÍS, during a visit to Madrid alongside his mentor, Michel Mayor, to give a talk at the Space Agency Center European Union (ESAC). The two Swiss astronomers won the Nobel Prize in Physics in 2019 for their discovery in 1995 of the first planet outside the solar system, known as the exoplanet. It was a giant gas planet orbiting the star 51 Pegasi, 50 light years from Earth. Today, just 26 years after the discovery, more than 4,500 exoplanets have been identified. When the CHEOPS European Space Telescope was launched in 2019 with the aim of determining the size of known exoplanets, Queloz’s first goal was to study 55 Cancri e.

“We have infrared observations of thermal emissions from this planet,” Queloz explains. “In addition, there is an observation in the visible light spectrum. These data do not give us a very clear idea of ​​what the planet looks like. We don’t know if it has an atmosphere or if any part of its surface is solid. It is also not known whether there is a seasonal evolution. Why is this important then? Because it is not much different from what the newly born Earth was, in its first 50 million years of life. It’s a little bigger, but it’s very similar. That is why we have to understand it. The best thing is that this planet is just in the right place. With CHEOPS we will be able to study its evolution, its reflectivity. One can even determine whether it has a permanent or temporary atmosphere. That’s why I’m so excited, ”he says of 55 Cancri e, which was renamed Janssen in 2015, in honor of telescope pioneer Zacharias Janssen.

It is tempting to imagine that in 4.5 billion years, the age of the Earth, there will still be humans following the evolutions of this lava world.

Planet 55 Canri e is not much different from the newly born Earth in its first 50 million years of life. That’s why we have to understand it

Astronomer Didier Queloz

The mayor explains that the other goal of exploring exoplanets is to find Earth’s twin planets with other stars. “In our research, we found a lot of stars that could house the equivalent of our solar system,” he says. “For a moment, imagine that we are the aliens in another part of the universe and we are looking at our own solar system through today’s telescopes. If that was the case, for the time being, we would only have discovered Jupiter and suspect that Saturn exists. We would have no idea of ​​the Earth, ”he explains. Most of the exoplanets discovered so far are large gas giants like Jupiter. These planets are very likely to be found on the outskirts of solar systems that have rocky planets, like Earth, in the inner zone. “But our technology is still too young to discover them,” explains the mayor.

Queloz is leading an international project to discover new planets. The project is based on HARPS3, a new instrument specially designed to perform the largest search for planets like the Earth in solar systems with stars like the Sun. HARPS3 will be installed in the Newton Telescope in La Palma, in the Spanish Canary Islands, off the coast of northwest Africa. This instrument takes current technology for detecting planets in other solar systems to the next level. Its mission is to achieve something that has never been done before. Stars like the Sun have an atmosphere, and these emit light signals – noise – that can mask the presence of a rocky planet. “We have to kill this noise and we don’t know when we can do it,” said the mayor.

HARPS3 will start operating in 2023 and will analyze 60 stars similar to the Sun. “My goal is that within 10 years, when I retire, this experience will be over,” Queloz explains. “I am convinced that by then we will have discovered an Earth twin. It is possible that there are even 10. But we might have bad luck and the 10 are like Venus. I believe that the Earth cannot be so strange, so unique.

Hunting for planets is only the first step. Astronomers will then have to determine if there is life on the planet. And this is where things get very complicated. Telescopes of today and those that will define the future of astronomical exploration in the coming decades, like the James Webb Space Telescope, can only detect signs of life – oxygen, water, and other components of an atmosphere that could indicate the presence of a life form. “Even with the right equipment, you’ll never be sure you’ve detected life,” Queloz explains. “A biologist won’t believe you until there is a huge amount of evidence, he probably won’t accept it until you bring him the living alien.”

I am convinced that within 10 years we will have discovered an Earth twin

Astronomer Didier Queloz

But reaching these worlds is impossible, says the mayor. “They are too far away. Remember the trip to the moon. We took three days to get there. The light makes the trip in a second. Imagine finding an Earth twin just 30 light years away. At that distance, it would be a very, very close neighbor. It would take a billion seconds for the light to get there. It’s a billion times farther than Apollo 11 [the spaceflight that first landed humans on the Moon] and this trip was the farthest humans have traveled on crewed missions. If you want to hit an exoplanet, you need to be able to craft a rocket that approaches the speed of light and, most importantly, decelerates when it is close to its destination. The energy required is simply gigantic, impossible to achieve.

The day after the Nobel Prize, the mayor accepted an interview with EL PAÍS, in which he said: “Religion says that God has decided that there will be life only here on Earth, and I have it. believed. Scientific facts show that life is a natural process. I believe the only answer is to investigate and find the answer, but for me there is no place for God in the universe. Mayor, however, recognizes that the technical limitations of humans mean that it will be impossible to know if there is life on an exoplanet for many centuries to come. But there is a shorter path, says Mayor: to seek life in areas of our own solar system, especially the frozen moons of Jupiter and Saturn. “We’re much more likely to be able to analyze and find alien life in these places,” he says.


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