2019 Nobel Prize In Physics: Evolution Of The Universe And Discovery Of Exoplanet Orbiting Solar-Type Star

 

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2019 “for contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos” with one half to James Peebles of Princeton University, USA, “for theoretical discoveries in physical cosmology” and the other half jointly to Michel Mayor of the University of Geneva, Switzerland, and Didier Queloz of the University of Geneva, Switzerland, and the University of Cambridge, UK, “for the discovery of an exoplanet orbiting a solar-type star.”

New perspectives on our place in the universe

This year’s Nobel Prize in Physics rewards new understanding of the universe’s structure and history, and the first discovery of a planet orbiting a solar-type star outside our solar system.

James Peebles’ insights into physical cosmology have enriched the entire field of research and laid a foundation for the transformation of cosmology over the last fifty years, from speculation to science. His theoretical framework, developed since the mid-1960s, is the basis of our contemporary ideas about the universe.

The Big Bang model describes the universe from its very first moments, almost 14 billion years ago, when it was extremely hot and dense. Since then, the universe has been expanding, becoming larger and colder. Barely 400,000 years after the Big Bang, the universe became transparent and light rays were able to travel through space. Even today, this ancient radiation is all around us and, coded into it, many of the universe’s secrets are hiding. Using his theoretical tools and calculations, James Peebles was able to interpret these traces from the infancy of the universe and discover new physical processes.

The results showed us a universe in which just five per cent of its content is known, the matter which constitutes stars, planets, trees — and us. The rest, 95 per cent, is unknown dark matter and dark energy. This is a mystery and a challenge to modern physics.

In October 1995, Michel Mayor and Didier Queloz announced the first discovery of a planet outside our solar system, an exoplanet, orbiting a solar-type star in our home galaxy, the Milky Way. At the Haute-Provence Observatory in southern France, using custom-made instruments, they were able to see planet 51 Pegasi b, a gaseous ball comparable with the solar system’s biggest gas giant, Jupiter.

This discovery started a revolution in astronomy and over 4,000 exoplanets have since been found in the Milky Way. Strange new worlds are still being discovered, with an incredible wealth of sizes, forms and orbits. They challenge our preconceived ideas about planetary systems and are forcing scientists to revise their theories of the physical processes behind the origins of planets. With numerous projects planned to start searching for exoplanets, we may eventually find an answer to the eternal question of whether other life is out there.

This year’s Laureates have transformed our ideas about the cosmos. While James Peebles’ theoretical discoveries contributed to our understanding of how the universe evolved after the Big Bang, Michel Mayor and Didier Queloz explored our cosmic neighbourhoods on the hunt for unknown planets. Their discoveries have forever changed our conceptions of the world.

James Peebles, born 1935 in Winnipeg, Canada. Ph.D. 1962 from Princeton University, USA. Albert Einstein Professor of Science at Princeton University, USA.

Michel Mayor, born 1942 in Lausanne, Switzerland. Ph.D. 1971 from University of Geneva, Switzerland. Professor at University of Geneva, Switzerland.

Didier Queloz, born 1966. Ph.D. 1995 from University of Geneva, Switzerland. Professor at University of Geneva, Switzerland and University of Cambridge, UK.

Prize amount: 9 million Swedish krona, with one half to James Peebles and the other half jointly to Michel Mayor and Didier Queloz

Galactic Fountains And Carousels: Order Emerging From Chaos

 

Scientists from Germany and the United States have unveiled the results of a newly-completed, state of the art simulation of the evolution of galaxies. TNG50 is the most detailed large-scale cosmological simulation yet. It allows researchers to study in detail how galaxies form, and how they have evolved since shortly after the Big Bang. For the first time, it reveals that the geometry of the cosmic gas flows around galaxies determines galaxies’ structures, and vice versa. The researchers publish their results in two papers in the journal Monthly Notices of the Royal Astronomical Society.

Astronomers running cosmological simulations face a fundamental trade-off: with finite computing power, typical simulations so far have been either very detailed or have spanned a large volume of virtual space, but have so far not been able to do both. Detailed simulations with limited volumes can model no more than a few galaxies, making statistical deductions difficult. Large-volume simulations, in turn, typically lack the details necessary to reproduce many of the small-scale properties we observe in our own Universe, reducing their predictive power.

The TNG50 simulation, which has just been published, manages to avoid this trade-off. For the first time, it combines the idea of a large-scale cosmological simulation — a Universe in a box — with the computational resolution of “zoom” simulations, at a level of detail that had previously only been possible for studies of individual galaxies.

In a simulated cube of space that is more than 230 million light-years across, TNG50 can discern physical phenomena that occur on scales one million times smaller, tracing the simultaneous evolution of thousands of galaxies over 13.8 billion years of cosmic history. It does so with more than 20 billion particles representing dark (invisible) matter, stars, cosmic gas, magnetic fields, and supermassive black holes. The calculation itself required 16,000 cores on the Hazel Hen supercomputer in Stuttgart, working together, 24/7, for more than a year — the equivalent of fifteen thousand years on a single processor, making it one of the most demanding astrophysical computations to date.

The first scientific results from TNG50 are published by a team led by Dr Annalisa Pillepich (Max Planck Institute for Astronomy, Heidelberg) and Dr Dylan Nelson (Max Planck Institute for Astrophysics, Garching) and reveal unforeseen physical phenomena. According to Nelson: “Numerical experiments of this kind are particularly successful when you get out more than you put in. In our simulation, we see phenomena that had not been programmed explicitly into the simulation code. These phenomena emerge in a natural fashion, from the complex interplay of the basic physical ingredients of our model universe.”

TNG50 features two prominent examples for this kind of emergent behaviour. The first concerns the formation of “disc” galaxies like our own Milky Way. Using the simulation as a time machine to rewind the evolution of cosmic structure, researchers have seen how the well-ordered, rapidly rotating disc galaxies (which are common in our nearby Universe) emerge from chaotic, disorganised, and highly turbulent clouds of gas at earlier epochs.

As the gas settles down, newborn stars are typically found on more and more circular orbits, eventually forming large spiral galaxies — galactic carousels. Annalisa Pillepich explains: “In practice, TNG50 shows that our own Milky Way galaxy with its thin disc is at the height of galaxy fashion: over the past 10 billion years, at least those galaxies that are still forming new stars have become more and more disc-like, and their chaotic internal motions have decreased considerably. The Universe was much messier when it was just a few billion years old!”

As these galaxies flatten out, researchers found another emergent phenomenon, involving the high-speed outflows and winds of gas flowing out of galaxies. This launched as a result of the explosions of massive stars (supernovae) and activity from supermassive black holes found at the heart of galaxies. Galactic gaseous outflows are initially also chaotic and flow away in all directions, but over time, they begin to become more focused along a path of least resistance.

In the late universe, flows out of galaxies take the form of two cones, emerging in opposite directions — like two ice cream cones placed tip to tip, with the galaxy swirling at the centre. These flows of material slow down as they attempt to leave the gravitational well of the galaxy’s halo of invisible — or dark — matter, and can eventually stall and fall back, forming a galactic fountain of recycled gas. This process redistributes gas from the centre of a galaxy to its outskirts, further accelerating the transformation of the galaxy itself into a thin disc: galactic structure shapes galactic fountains, and vice versa.

The team of scientists creating TNG50 (based at Max-Planck-Institutes in Garching and Heidelberg, Harvard University, MIT, and the Center for Computational Astrophysics (CCA)) will eventually release all simulation data to the astronomy community at large, as well as to the public. This will allow astronomers all over the world to make their own discoveries in the TNG50 universe — and possibly find additional examples of emergent cosmic phenomena, of order emerging from chaos.

Black Holes Stunt Growth Of Dwarf Galaxies

 

Astronomers at the University of California, Riverside, have discovered that powerful winds driven by supermassive black holes in the centers of dwarf galaxies have a significant impact on the evolution of these galaxies by suppressing star formation.

Dwarf galaxies are small galaxies that contain between 100 million to a few billion stars. In contrast, the Milky Way has 200-400 billion stars. Dwarf galaxies are the most abundant galaxy type in the universe and often orbit larger galaxies.

The team of three astronomers was surprised by the strength of the detected winds.

“We expected we would need observations with much higher resolution and sensitivity, and we had planned on obtaining these as a follow-up to our initial observations,” said Gabriela Canalizo, a professor of physics and astronomy at UC Riverside, who led the research team. “But we could see the signs strongly and clearly in the initial observations. The winds were stronger than we had anticipated.”

Canalizo explained that astronomers have suspected for the past couple of decades that supermassive black holes at the centers of large galaxies can have a profound influence on the way large galaxies grow and age.

“Our findings now indicate that their effect can be just as dramatic, if not more dramatic, in dwarf galaxies in the universe,” she said.

Study results appear in The Astrophysical Journal.

The researchers, who also include Laura V. Sales, an assistant professor of physics and astronomy; and Christina M. Manzano-King, a doctoral student in Canalizo’s lab, used a portion of the data from the Sloan Digital Sky Survey, which maps more than 35% of the sky, to identify 50 dwarf galaxies, 29 of which showed signs of being associated with black holes in their centers. Six of these 29 galaxies showed evidence of winds — specifically, high-velocity ionized gas outflows — emanating from their active black holes.

“Using the Keck telescopes in Hawaii, we were able to not only detect, but also measure specific properties of these winds, such as their kinematics, distribution, and power source — the first time this has been done,” Canalizo said. “We found some evidence that these winds may be changing the rate at which the galaxies are able to form stars.”

Manzano-King, the first author of the research paper, explained that many unanswered questions about galaxy evolution can be understood by studying dwarf galaxies.

“Larger galaxies often form when dwarf galaxies merge together,” she said. “Dwarf galaxies are, therefore, useful in understanding how galaxies evolve. Dwarf galaxies are small because after they formed, they somehow avoided merging with other galaxies. Thus, they serve as fossils by revealing what the environment of the early universe was like. Dwarf galaxies are the smallest galaxies in which we are directly seeing winds — gas flows up to 1,000 kilometers per second — for the first time.”

Manzano-King explained that as material falls into a black hole, it heats up due to friction and strong gravitational fields and releases radiative energy. This energy pushes ambient gas outward from the center of the galaxy into intergalactic space.

“What’s interesting is that these winds are being pushed out by active black holes in the six dwarf galaxies rather than by stellar processes such as supernovae,” she said. “Typically, winds driven by stellar processes are common in dwarf galaxies and constitute the dominant process for regulating the amount of gas available in dwarf galaxies for forming stars.”

Astronomers suspect that when wind emanating from a black hole is pushed out, it compresses the gas ahead of the wind, which can increase star formation. But if all the wind gets expelled from the galaxy’s center, gas becomes unavailable and star formation could decrease. The latter appears to be what is occurring in the six dwarf galaxies the researchers identified.

“In these six cases, the wind has a negative impact on star formation,” Sales said. “Theoretical models for the formation and evolution of galaxies have not included the impact of black holes in dwarf galaxies. We are seeing evidence, however, of a suppression of star formation in these galaxies. Our findings show that galaxy formation models must include black holes as important, if not dominant, regulators of star formation in dwarf galaxies.”

Next, the researchers plan to study the mass and momentum of gas outflows in dwarf galaxies.

“This would better inform theorists who rely on such data to build models,” Manzano-King said. “These models, in turn, teach observational astronomers just how the winds affect dwarf galaxies. We also plan to do a systematic search in a larger sample of the Sloan Digital Sky Survey to identify dwarf galaxies with outflows originating in active black holes.”

The research was funded by the National Science Foundation, NASA, and the Hellman Foundation. Data was obtained at the W. M. Keck Observatory, and made possible by financial support from the W. M. Keck Foundation.

Astronomers Catch Wind Rushing Out Of Galaxy

 

Exploring the influence of galactic winds from a distant galaxy called Makani, UC San Diego’s Alison Coil, Rhodes College’s David Rupke and a group of collaborators from around the world made a novel discovery. Published in Nature, their study’s findings provide direct evidence for the first time of the role of galactic winds — ejections of gas from galaxies — in creating the circumgalactic medium (CGM). It exists in the regions around galaxies, and it plays an active role in their cosmic evolution. The unique composition of Makani — meaning wind in Hawaiian — uniquely lent itself to the breakthrough findings.

“Makani is not a typical galaxy,” noted Coil, a physics professor at UC San Diego. “It’s what’s known as a late-stage major merger — two recently combined similarly massive galaxies, which came together because of the gravitational pull each felt from the other as they drew nearer. Galaxy mergers often lead to starburst events, when a substantial amount of gas present in the merging galaxies is compressed, resulting in a burst of new star births. Those new stars, in the case of Makani, likely caused the huge outflows — either in stellar winds or at the end of their lives when they exploded as supernovae.”

Coil explained that most of the gas in the universe inexplicably appears in the regions surrounding galaxies — not in the galaxies. Typically, when astronomers observe a galaxy, they are not witnessing it undergoing dramatic events — big mergers, the rearrangement of stars, the creation of multiple stars or driving huge, fast winds.

“While these events may occur at some point in a galaxy’s life, they’d be relatively brief,” noted Coil. “Here, we’re actually catching it all right as it’s happening through these huge outflows of gas and dust.”

Coil and Rupke, the paper’s first author, used data collected from the W. M. Keck Observatory’s new Keck Cosmic Web Imager (KCWI) instrument, combined with images from the Hubble Space Telescope and the Atacama Large Millimeter Array (ALMA), to draw their conclusions. The KCWI data provided what the researchers call the “stunning detection” of the ionized oxygen gas to extremely large scales, well beyond the stars in the galaxy. It allowed them to distinguish a fast gaseous outflow launched from the galaxy a few million year ago, from a gas outflow launched hundreds of millions of years earlier that has since slowed significantly.

“The earlier outflow has flowed to large distances from the galaxy, while the fast, recent outflow has not had time to do so,” summarized Rupke, associate professor of physics at Rhodes College.

From the Hubble, the researchers procured images of Makani’s stars, showing it to be a massive, compact galaxy that resulted from a merger of two once separate galaxies. From ALMA, they could see that the outflow contains molecules as well as atoms. The data sets indicated that with a mixed population of old, middle-age and young stars, the galaxy might also contain a dust-obscured accreting supermassive black hole. This suggests to the scientists that Makani’s properties and timescales are consistent with theoretical models of galactic winds.

“In terms of both their size and speed of travel, the two outflows are consistent with their creation by these past starburst events; they’re also consistent with theoretical models of how large and fast winds should be if created by starbursts. So observations and theory are agreeing well here,” noted Coil.

Rupke noticed that the hourglass shape of Makani’s nebula is strongly reminiscent of similar galactic winds in other galaxies, but that Makani’s wind is much larger than in other observed galaxies.

“This means that we can confirm it’s actually moving gas from the galaxy into the circumgalactic regions around it, as well as sweeping up more gas from its surroundings as it moves out,” Rupke explained. “And it’s moving a lot of it — at least one to 10 percent of the visible mass of the entire galaxy — at very high speeds, thousands of kilometers per second.”

Rupke also noted that while astronomers are converging on the idea that galactic winds are important for feeding the CGM, most of the evidence has come from theoretical models or observations that don’t encompass the entire galaxy.

“Here we have the whole spatial picture for one galaxy, which is a remarkable illustration of what people expected,” he said. “Makani’s existence provides one of the first direct windows into how a galaxy contributes to the ongoing formation and chemical enrichment of its CGM.”

This study was supported by the National Science Foundation (collaborative grant AST-1814233, 1813365, 1814159 and 1813702), NASA (award SOF-06-0191, issued by USRA), Rhodes College and the Royal Society.

Scientists May Have Discovered Whole New Class Of Black Holes

 

Black holes are an important part of how astrophysicists make sense of the universe — so important that scientists have been trying to build a census of all the black holes in the Milky Way galaxy.

But new research shows that their search might have been missing an entire class of black holes that they didn’t know existed.

In a study published today in the journal Science, astronomers offer a new way to search for black holes, and show that it is possible there is a class of black holes smaller than the smallest known black holes in the universe.

“We’re showing this hint that there is another population out there that we have yet to really probe in the search for black holes,” said Todd Thompson, a professor of astronomy at The Ohio State University and lead author of the study.

“People are trying to understand supernova explosions, how supermassive black stars explode, how the elements were formed in supermassive stars. So if we could reveal a new population of black holes, it would tell us more about which stars explode, which don’t, which form black holes, which form neutron stars. It opens up a new area of study.”

Imagine a census of a city that only counted people 5’9″ and taller — and imagine that the census takers didn’t even know that people shorter than 5’9″ existed. Data from that census would be incomplete, providing an inaccurate picture of the population. That is essentially what has been happening in the search for black holes, Thompson said.

Astronomers have long been searching for black holes, which have gravitational pulls so fierce that nothing — not matter, not radiation — can escape. Black holes form when some stars die, shrink into themselves, and explode. Astronomers have also been looking for neutron stars — small, dense stars that form when some stars die and collapse.

Both could hold interesting information about the elements on Earth and about how stars live and die. But in order to uncover that information, astronomers first have to figure out where the black holes are. And to figure out where the black holes are, they need to know what they are looking for.

One clue: Black holes often exist in something called a binary system. This simply means that two stars are close enough to one another to be locked together by gravity in a mutual orbit around one another. When one of those stars dies, the other can remain, still orbiting the space where the dead star — now a black hole or neutron star — once lived, and where a black hole or neutron star has formed.

For years, the black holes scientists knew about were all between approximately five and 15 times the mass of the sun. The known neutron stars are generally no bigger than about 2.1 times the mass of the sun — if they were above 2.5 times the sun’s mass, they would collapse to a black hole.

But in the summer of 2017, a survey called LIGO — the Laser Interferometer Gravitational-Wave Observatory — saw two black holes merging together in a galaxy about 1.8 million light years away. One of those black holes was about 31 times the mass of the sun; the other about 25 times the mass of the sun.

“Immediately, everyone was like ‘wow,’ because it was such a spectacular thing,” Thompson said. “Not only because it proved that LIGO worked, but because the masses were huge. Black holes that size are a big deal — we hadn’t seen them before.”

Thompson and other astrophysicists had long suspected that black holes might come in sizes outside the known range, and LIGO’s discovery proved that black holes could be larger. But there remained a window of size between the biggest neutron stars and the smallest black holes.

Thompson decided to see if he could solve that mystery.

He and other scientists began combing through data from APOGEE, the Apache Point Observatory Galactic Evolution Experiment, which collected light spectra from around 100,000 stars across the Milky Way. The spectra, Thompson realized, could show whether a star might be orbiting around another object: Changes in spectra — a shift toward bluer wavelengths, for example, followed by a shift to redder wavelengths — could show that a star was orbiting an unseen companion.

Thompson began combing through the data, looking for stars that showed that change, indicating that they might be orbiting a black hole.

Then, he narrowed the APOGEE data to 200 stars that might be most interesting. He gave the data to a graduate research associate at Ohio State, Tharindu Jayasinghe, who compiled thousands of images of each potential binary system from ASAS-SN, the All-Sky Automated Survey for Supernovae. (ASAS-SN has found some 1,000 supernovae, and is run out of Ohio State.)

Their data crunching found a giant red star that appeared to be orbiting something, but that something, based on their calculations, was likely much smaller than the known black holes in the Milky Way, but way bigger than most known neutron stars.

After more calculations and additional data from the Tillinghast Reflector Echelle Spectrograph and the Gaia satellite, they realized they had found a low-mass black hole, likely about 3.3 times the mass of the sun.

“What we’ve done here is come up with a new way to search for black holes, but we’ve also potentially identified one of the first of a new class of low-mass black holes that astronomers hadn’t previously known about.” Thompson said. “The masses of things tell us about their formation and evolution, and they tell us about their nature.”

Mars Once Had Salt Lakes Similar To Those On Earth

 

Mars once had salt lakes that are similar to those on Earth and has gone through wet and dry periods, according to an international team of scientists that includes a Texas A&M University College of Geosciences researcher.

Marion Nachon, a postdoctoral research associate in the Department of Geology and Geophysics at Texas A&M, and colleagues have had their work published in the current issue of Nature Geoscience.

The team examined Mars’ geological terrains from Gale Crater, an immense 95-mile-wide rocky basin that is being explored with the NASA Curiosity rover since 2012 as part of the MSL (Mars Science Laboratory) mission.

The results show that the lake that was present in Gale Crater over 3 billion years ago underwent a drying episode, potentially linked to the global drying of Mars.

Gale Crater formed about 3.6 billion years ago when a meteor hit Mars and created its large impact crater.

“Since then, its geological terrains have recorded the history of Mars, and studies have shown Gale Crater reveals signs that liquid water was present over its history, which is a key ingredient of microbial life as we know it,” Nachon said. “During these drying periods, salt ponds eventually formed. It is difficult to say exactly how large these ponds were, but the lake in Gale Crater was present for long periods of time — from at least hundreds of years to perhaps tens of thousands of years,” Nachon said.

So what happened to these salt lakes?

Nachon said that Mars probably became dryer over time, and the planet lost its planetary magnetic field, which left the atmosphere exposed to be stripped by solar wind and radiation over millions of years.

“With an atmosphere becoming thinner, the pressure at the surface became lesser, and the conditions for liquid water to be stable at the surface were not fulfilled anymore,” Nachon said. “So liquid water became unsustainable and evaporated.”

The salt ponds on Mars are believed to be similar to some found on Earth, especially those in a region called Altiplano, which is near the Bolivia-Peru border.

Nachon said the Altiplano is an arid, high-altitude plateau where rivers and streams from mountain ranges “do not flow to the sea but lead to closed basins, similar to what used to happen at Gale Crater on Mars,” she said. “This hydrology creates lakes with water levels heavily influenced by climate. During the arid periods Altiplano lakes become shallow due to evaporation, and some even dry up entirely. The fact that the Atliplano is mostly vegetation free makes the region look even more like Mars,” she said.”

Nachon added that the study shows that the ancient lake in Gale Crater underwent at least one episode of drying before “recovering.” It’s also possible that the lake was segmented into separate ponds, where some of the ponds could have undergone more evaporation.

Because up to now only one location along the rover’s path shows such a drying history, Nachon said it might give clues about how many drying episodes the lake underwent before Mars’s climate became as dry as it is currently.

“It could indicate that Mars’s climate ‘dried out’ over the long term, on a way that still allowed for the cyclical presence of a lake,” Nachon said. “These results indicate a past Mars climate that fluctuated between wetter and drier periods. They also tell us about the types of chemical elements (in this case sulphur, a key ingredient for life) that were available in the liquid water present at the surface at the time, and about the type of environmental fluctuations Mars life would have had to cope with, if it ever existed.”

Water Detected On An Exoplanet Located In Its Star’s Habitable Zone

 

 

Ever since the discovery of the first exoplanet in the 1990s, astronomers have made steady progress towards finding and probing planets located in the habitable zone of their stars, where conditions can lead to the formation of liquid water and the proliferation of life.

Results from the Kepler satellite mission, which discovered nearly 2/3 of all known exoplanets to date, indicate that 5 to 20% of Earths and super-Earths are located in the habitable zone of their stars. However, despite this abundance, probing the conditions and atmospheric properties on any of these habitable zone planets is extremely difficult and has remained elusive… until now.

A new study by Professor Björn Benneke of the Institute for Research on Exoplanets at the Université de Montréal, his doctoral student Caroline Piaulet and several of their collaborators reports the detection of water vapour and perhaps even liquid water clouds in the atmosphere of the planet K2-18b. This exoplanet is about nine times more massive than our Earth and is found in the habitable zone of the star it orbits. This M-type star is smaller and cooler than our Sun, but due to K2-18b’s close proximity to its star, the planet receives almost the same total amount of energy from its star as our Earth receives from the Sun.

The similarities between the exoplanet K2-18b and the Earth suggest to astronomers that the exoplanet may potentially have a water cycle possibly allowing water to condense into clouds and liquid water rain to fall. This detection was made possible by combining eight transit observations — the moment when an exoplanet passes in front of its star — taken by the Hubble Space Telescope.

The Université de Montréal is no stranger to the K2-18 system located 111 light years away. The existence of K2-18b was first confirmed by Prof. Benneke and his team in a 2016 paper using data from the Spitzer Space Telescope. The mass and radius of the planet were then determined by former Université de Montréal and University of Toronto PhD student Ryan Cloutier. These promising initial results encouraged the iREx team to collect follow-up observations of the intriguing world.”

Scientists currently believe that the thick gaseous envelope of K2-18b likely prevents life as we know it from existing on the planet’s surface. However, the study shows that even these planets of relatively low mass which are therefore more difficult to study can be explored using astronomical instruments developed in recent years. By studying these planets which are in the habitable zone of their star and have the right conditions for liquid water, astronomers are one step closer to directly detecting signs of life beyond our Solar System.

“This represents the biggest step yet taken towards our ultimate goal of finding life on other planets, of proving that we are not alone. Thanks to our observations and our climate model of this planet, we have shown that its water vapour can condense into liquid water. This is a first,” says Björn Benneke.