‘Extraordinary claims require extraordinary evidence’ − an astronomer explains how much evidence scientists need to claim discoveries like extraterrestrial life
The universe is filled with countless galaxies, stars and planets. Astronomers may find life one day, but they will need extraordinary proof. ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi Chris Impey, University of Arizona The detection of life beyond Earth would be one of the most profound discoveries in the history of science. The Milky Way galaxy alone hosts hundreds of millions of potentially habitable planets. Astronomers are using powerful space telescopes to look for molecular indicators of biology in the atmospheres of the most Earth-like of these planets. But so far, no solid evidence of life has ever been found beyond the Earth. A paper published in April 2025 claimed to detect a signature of life in the atmosphere of the planet K2-18b. And while this discovery is intriguing, most astronomers – including the paper’s authors – aren’t ready to claim that it means extraterrestrial life exists. A detection of life would be a remarkable development. The astronomer Carl Sagan used the phrase, “Extraordinary claims require extraordinary evidence,” in regard to searching for alien life. It conveys the idea that there should be a high bar for evidence to support a remarkable claim. I’m an astronomer who has written a book about astrobiology. Over my career, I’ve seen some compelling scientific discoveries. But to reach this threshold of finding life beyond Earth, a result needs to fit several important criteria.
When is a result important and reliable?
There are three criteria for a scientific result to represent a true discovery and not be subject to uncertainty and doubt. How does the claim of life on K2-18b measure up? First, the experiment needs to measure a meaningful and important quantity. Researchers observed K2-18b’s atmosphere with the James Webb Space Telescope and saw a spectral feature that they identified as dimethyl sulfide. On Earth, dimethyl sulfide is associated with biology, in particular bacteria and plankton in the oceans. However, it can also arise by other means, so this single molecule is not conclusive proof of life. Second, the detection needs to be strong. Every detector has some noise from the random motion of electrons. The signal should be strong enough to have a low probability of arising by chance from this noise. The K2-18b detection has a significance of 3-sigma, which means it has a 0.3% probability of arising by chance. That sounds low, but most scientists would consider that a weak detection. There are many molecules that could create a feature in the same spectral range. The “gold standard” for scientific detection is 5-sigma, which means the probability of the finding happening by chance is less than 0.00006%. For example, physicists at CERN gathered data patiently for two years until they had a 5-sigma detection of the Higgs boson particle, leading to a Nobel Prize one year later in 2013.The announcement of the discovery of the Higgs boson took decades from the time Peter Higgs first predicted the existence of the particle. Scientists, such as Joe Incandela shown here, waited until they’d reached that 5-sigma level to say, ‘I think we have it.’ Third, a result needs to be repeatable. Results are considered reliable when they’ve been repeated – ideally corroborated by other investigators or confirmed using a different instrument. For K2-18b, this might mean detecting other molecules that indicate biology, such as oxygen in the planet’s atmosphere. Without more and better data, most researchers are viewing the claim of life on K2-18b with skepticism.
Claims of life on Mars
In the past, some scientists have claimed to have found life much closer to home, on the planet Mars. Over a century ago, retired Boston merchant turned astronomer Percival Lowell claimed that linear features he saw on the surface of Mars were canals, constructed by a dying civilization to transport water from the poles to the equator. Artificial waterways on Mars would certainly have been a major discovery, but this example failed the other two criteria: strong evidence and repeatability. Lowell was misled by his visual observations, and he was engaging in wishful thinking. No other astronomers could confirm his findings.Mars, as taken by the OSIRIS instrument on the ESA Rosetta spacecraft during its February 2007 flyby of the planet and adjusted to show color.ESA & MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA, CC BY-SA In 1996, NASA held a press conference where a team of scientists presented evidence for biology in the Martian meteorite ALH 84001. Their evidence included an evocative image that seemed to show microfossils in the meteorite. However, scientists have come up with explanations for the meteorite’s unusual features that do not involve biology. That extraordinary claim has dissipated. More recently, astronomers detected low levels of methane in the atmosphere of Mars. Like dimethyl sulfide and oxygen, methane on Earth is made primarily – but not exclusively – by life. Different spacecraft and rovers on the Martian surface have returned conflicting results, where a detection with one spacecraft was not confirmed by another. The low level and variability of methane on Mars is still a mystery. And in the absence of definitive evidence that this very low level of methane has a biological origin, nobody is claiming definitive evidence of life on Mars.
Claims of advanced civilizations
Detecting microbial life on Mars or an exoplanet would be dramatic, but the discovery of extraterrestrial civilizations would be truly spectacular. The search for extraterrestrial intelligence, or SETI, has been underway for 75 years. No messages have ever been received, but in 1977 a radio telescope in Ohio detected a strong signal that lasted only for a minute. This signal was so unusual that an astronomer working at the telescope wrote “Wow!” on the printout, giving the signal its name. Unfortunately, nothing like it has since been detected from that region of the sky, so the Wow! Signal fails the test of repeatability.‘Oumuamua is the first object passing through the solar system that astronomers have identified as having interstellar origins.European Southern Observatory/M. Kornmesser In 2017, a rocky, cigar-shaped object called ‘Oumuamua was the first known interstellar object to visit the solar system. ‘Oumuamua’s strange shape and trajectory led Harvard astronomer Avi Loeb to argue that it was an alien artifact. However, the object has already left the solar system, so there’s no chance for astronomers to observe it again. And some researchers have gathered evidence suggesting that it’s just a comet. While many scientists think we aren’t alone, given the enormous amount of habitable real estate beyond Earth, no detection has cleared the threshold enunciated by Carl Sagan.
Claims about the universe
These same criteria apply to research about the entire universe. One particular concern in cosmology is the fact that, unlike the case of planets, there is only one universe to study. A cautionary tale comes from attempts to show that the universe went through a period of extremely rapid expansion a fraction of a second after the Big Bang. Cosmologists call this event inflation, and it is invoked to explain why the universe is now smooth and flat. In 2014, astronomers claimed to have found evidence for inflation in a subtle signal from microwaves left over after the Big Bang. Within a year, however, the team retracted the result because the signal had a mundane explanation: They had confused dust in our galaxy with a signature of inflation. On the other hand, the discovery of the universe’s acceleration shows the success of the scientific method. In 1929, astronomer Edwin Hubble found that the universe was expanding. Then, in 1998, evidence emerged that this cosmic expansion is accelerating. Physicists were startled by this result. Two research groups used supernovae to separately trace the expansion. In a friendly rivalry, they used different sets of supernovae but got the same result. Independent corroboration increased their confidence that the universe was accelerating. They called the force behind this accelerating expansion dark energy and received a Nobel Prize in 2011 for its discovery. On scales large and small, astronomers try to set a high bar of evidence before claiming a discovery.Chris Impey, University Distinguished Professor of Astronomy, University of Arizona This article is republished from The Conversation under a Creative Commons license. Read the original article.
NASA goes on an ESCAPADE – twin small, low-cost orbiters will examine Mars’ atmosphere
NASA’s ESCAPADE mission launched two small, affordable orbiters to Mars on Blue Origin’s New Glenn rocket. Discover how these twin spacecraft will study Mars’ atmosphere, test new trajectories, and usher in a new era of rapid, low-cost space exploration.
NASA goes on an ESCAPADE – twin small, low-cost orbiters will examine Mars’ atmosphere
Christopher Carr, Georgia Institute of Technology and Glenn Lightsey, Georgia Institute of Technology Envision a time when hundreds of spacecraft are exploring the solar system and beyond. That’s the future that NASA’s ESCAPADE, or Escape and Plasma Acceleration and Dynamics Explorers, mission will help unleash: one where small, low-cost spacecraft enable researchers to learn rapidly, iterate, and advance technology and science. The ESCAPADE mission launched on Nov. 13, 2025 on a Blue Origin New Glenn rocket, sending two small orbiters to Mars to study its atmosphere. As aerospace engineers, we’re excited about this mission because not only will it do great science while advancing the deep space capabilities of small spacecraft, but it also will travel to the red planet on an innovative new trajectory. The ESCAPADE mission is actually two spacecraft instead of one. Two identical spacecraft will take simultaneous measurements, resulting in better science. These spacecraft are smaller than those used in the past, each about the size of a copy machine, partly enabled by an ongoing miniaturization trend in the space industry. Doing more with less is very important for space exploration, because it typically takes most of the mass of a spacecraft simply to transport it where you want it to go.The ESCAPADE mission logo shows the twin orbiters.TRAX International/Kristen Perrin Having two spacecraft also acts as an insurance policy in case one of them doesn’t work as planned. Even if one completely fails, researchers can still do science with a single working spacecraft. This redundancy enables each spacecraft to be built more affordably than in the past, because the copies allow for more acceptance of risk.
Space is not a friendly place. Most of it is a vacuum – that is, mostly empty, without the gas molecules that create pressure and allow you to breathe or transfer heat. These molecules keep things from getting too hot or too cold. In space, with no pressure, a spacecraft can easily get too hot or too cold, depending on whether it is in sunlight or in shadow. In addition, the Sun and other, farther astronomical objects emit radiation that living things do not experience on Earth. Earth’s magnetic field protects you from the worst of this radiation. So when humans or our robotic representatives leave the Earth, our spacecraft must survive in this extreme environment not present on Earth. ESCAPADE will overcome these challenges with a shoestring budget totaling US$80 million. That is a lot of money, but for a mission to another planet it is inexpensive. It has kept costs low by leveraging commercial technologies for deep space exploration, which is now possible because of prior investments in fundamental research. For example, the GRAIL mission, launched in 2011, previously used two spacecraft, Ebb and Flow, to map the Moon’s gravity fields. ESCAPADE takes this concept to another world, Mars, and costs a fraction as much as GRAIL. Led by Rob Lillis of UC Berkeley’s Space Sciences Laboratory, this collaboration between spacecraft builders Rocket Lab, trajectory specialists Advanced Space LLC and launch provider Blue Origin – all commercial partners funded by NASA – aims to show that deep space exploration is now faster, more agile and more affordable than ever before.NASA’s ESCAPADE represents a partnership between a university, commercial companies and the government.
How will ESCAPADE get to Mars?
ESCAPADE will also use a new trajectory to get to Mars. Imagine being an archer in the Olympics. To hit a bull’s-eye, you have to shoot an arrow through a 15-inch – 40-centimeter – circle from a distance of 300 feet, or 90 meters. Now imagine the bull’s-eye represents Mars. To hit it from Earth, you would have to shoot an arrow through the same 15-inch bull’s-eye at a distance of over 13 miles, or 22 kilometers. You would also have to shoot the arrow in a curved path so that it goes around the Sun. Not only that, but Mars won’t be at the bull’s-eye at the time you shoot the arrow. You must shoot for the spot that Mars will be in 10 months from now. This is the problem that the ESCAPADE mission designers faced. What is amazing is that the physical laws and forces of nature are so predictable that this was not even the hardest problem to solve for the ESCAPADE mission. It takes energy to get from one place to another. To go from Earth to Mars, a spacecraft has to carry the energy it needs, in the form of rocket fuel, much like gasoline in a car. As a result, a high percentage of the total launch mass has to be fuel for the trip. When going to Mars orbit from Earth orbit, as much as 80% to 85% of the spacecraft mass has to be propellant, which means not much mass is dedicated to the part of the spacecraft that does all the experiments. This issue makes it important to pack as much capability into the rest of the spacecraft as possible. For ESCAPADE, the propellant is only about 65% of the spacecraft’s mass. ESCAPADE’s route is particularly fuel-efficient. First, Blue and Gold will go to the L2 Lagrange point, one of five places where gravitational forces of the Sun and Earth cancel out. Then, after about a year, during which they will collect data monitoring the Sun, they will fly by the Earth, using its gravitational field to get a boost. This way, they will arrive at Mars in about 10 more months. This new approach has another advantage beyond needing to carry less fuel: Trips from Earth to Mars are typically favorable to save fuel about every 26 months due to the two planets’ relative positions. However, this new trajectory makes the departure time more flexible. Future cargo and human missions could use a similar trajectory to have more frequent and less time-constrained trips to Mars. ESCAPADE is a testament to a new era in spaceflight. For a new generation of scientists and engineers, ESCAPADE is not just a mission – it is a blueprint for a new collaborative era of exploration and discovery. This article was updated on Nov. 13, 2025 to reflect the ESCAPADE launch’s date and success.Christopher Carr, Assistant Professor of Aerospace Engineering, Georgia Institute of Technology and Glenn Lightsey, Professor of Space Systems Technology, Georgia Institute of Technology This article is republished from The Conversation under a Creative Commons license. Read the original article.
Where Is Most Normal Matter in the Universe? Astronomers Map the Invisible
Most normal matter in the universe isn’t found in stars or planets. Discover how astronomers traced it to the cosmic web between galaxies using fast radio bursts and what this means for our understanding of the cosmos.
Mysterious blasts of radio waves from across the universe called fast radio bursts help astronomers catalog matter. ESO/M. Kornmesser, CC BY-SA
Most normal matter in the universe isn’t found in planets, stars or galaxies – an astronomer explains where it’s distributed
Chris Impey, University of Arizona If you look across space with a telescope, you’ll see countless galaxies, most of which host large central black holes, billions of stars and their attendant planets. The universe teems with huge, spectacular objects, and it might seem like these massive objects should hold most of the universe’s matter. But the Big Bang theory predicts that about 5% of the universe’s contents should be atoms made of protons, neutrons and electrons. Most of those atoms cannot be found in stars and galaxies – a discrepancy that has puzzled astronomers. If not in visible stars and galaxies, the most likely hiding place for the matter is in the dark space between galaxies. While space is often referred to as a vacuum, it isn’t completely empty. Individual particles and atoms are dispersed throughout the space between stars and galaxies, forming a dark, filamentary network called the “cosmic web.” Throughout my career as an astronomer, I’ve studied this cosmic web, and I know how difficult it is to account for the matter spread throughout space. In a study published in June 2025, a team of scientists used a unique radio technique to complete the census of normal matter in the universe.
The census of normal matter
The most obvious place to look for normal matter is in the form of stars. Gravity gathers stars together into galaxies, and astronomers can count galaxies throughout the observable universe. The census comes to several hundred billion galaxies, each made of several hundred billion stars. The numbers are uncertain because many stars lurk outside of galaxies. That’s an estimated 1023 stars in the universe, or hundreds of times more than the number of sand grains on all of Earth’s beaches. There are an estimated 1082 atoms in the universe. However, this prodigious number falls far short of accounting for all the matter predicted by the Big Bang. Careful accounting indicates that stars contain only 0.5% of the matter in the universe. Ten times more atoms are presumably floating freely in space. Just 0.03% of the matter is elements other than hydrogen and helium, including carbon and all the building blocks of life.
Looking between galaxies
The intergalactic medium – the space between galaxies – is near-total vacuum, with a density of one atom per cubic meter, or one atom every 35 cubic feet. That’s less than a billionth of a billionth of the density of air on Earth. Even at this very low density, this diffuse medium adds up to a lot of matter, given the enormous, 92-billion-light-year diameter of the universe. The intergalactic medium is very hot, with a temperature of millions of degrees. That makes it difficult to observe except with X-ray telescopes, since very hot gas radiates out through the universe at very short X-ray wavelengths. X-ray telescopes have limited sensitivity because they are smaller than most optical telescopes.
Deploying a new tool
Astronomers recently used a new tool to solve this missing matter problem. Fast radio bursts are intense blasts of radio waves that can put out as much energy in a millisecond as the Sun puts out in three days. First discovered in 2007, scientists found that the bursts are caused by compact stellar remnants in distant galaxies. Their energy peters out as the bursts travel through space, and by the time that energy reaches the Earth, it is a thousand times weaker than a mobile phone signal would be if emitted on the Moon, then detected on Earth. Research from early 2025 suggests the source of the bursts is the highly magnetic region around an ultra-compact neutron star. Neutron stars are incredibly dense remnants of massive stars that have collapsed under their own gravity after a supernova explosion. The particular type of neutron star that emits radio bursts is called a magnetar, with a magnetic field a thousand trillion times stronger than the Earth’s.A magnetar is a rare type of neutron star with an extremely strong magnetic field.ESO/L. Calçada, CC BY-ND Even though astronomers don’t fully understand fast radio bursts, they can use them to probe the spaces between galaxies. As the bursts travel through space, interactions with electrons in the hot intergalactic gas preferentially slow down longer wavelengths. The radio signal is spread out, analogous to the way a prism turns sunlight into a rainbow. Astronomers use the amount of spreading to calculate how much gas the burst has passed through on its way to Earth.
Puzzle solved
In the new study, published in June 2025, a team of astronomers from Caltech and the Harvard Center for Astrophysics studied 69 fast radio bursts using an array of 110 radio telescopes in California. The team found that 76% of the universe’s normal matter lies in the space between galaxies, with another 15% in galaxy halos – the area surrounding the visible stars in a galaxy – and the remaining 9% in stars and cold gas within galaxies. The complete accounting of normal matter in the universe provides a strong affirmation of the Big Bang theory. The theory predicts the abundance of normal matter formed in the first few minutes of the universe, so by recovering the predicted 5%, the theory passes a critical test. Several thousand fast radio bursts have already been observed, and an upcoming array of radio telescopes will likely increase the discovery rate to 10,000 per year. Such a large sample will let fast radio bursts become powerful tools for cosmology. Cosmology is the study of the size, shape and evolution of the universe. Radio bursts could go beyond counting atoms to mapping the three-dimensional structure of the cosmic web.
Pie chart of the universe
Scientists may now have the complete picture of where normal matter is distributed, but most of the universe is still made up of stuff they don’t fully understand. The most abundant ingredients in the universe are dark matter and dark energy, both of which are poorly understood. Dark energy is causing the accelerating expansion of the universe, and dark matter is the invisible glue that holds galaxies and the universe together.Despite physicists not knowing much about it, dark matter makes up around 27% of the universe.Visual Capitalist/Science Photo Library via Getty Images Dark matter is probably a previously unstudied type of fundamental particle that is not part of the standard model of particle physics. Physicists haven’t been able to detect this novel particle yet, but we know it exists because, according to general relativity, mass bends light, and far more gravitational lensing is seen than can be explained by visible matter. With gravitational lensing, a cluster of galaxies bends and magnifies light in a way that’s analogous to an optical lens. Dark matter outweighs conventional matter by more than a factor of five. One mystery may be solved, but a larger mystery remains. While dark matter is still enigmatic, we now know a lot about the normal atoms making up us as humans, and the world around us.
Most normal matter in the universe isn’t found in planets, stars or galaxies – an astronomer explains where it’s distributed
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Habitable Zone Planets: How Scientists Search for Liquid Water Beyond Earth
Habitable zone planets: Scientists use the habitable zone to find planets that could host liquid water and life. Learn how planetary atmospheres and geology determine true habitability beyond Earth.
Some exoplanets, like the one shown in this illustration, may have atmospheres that could make them potentially suitable for life. NASA/JPL-Caltech via AP
Habitable Zone Planets: How Scientists Search for Liquid Water Beyond Earth
Morgan Underwood, Rice University When astronomers search for planets that could host liquid water on their surface, they start by looking at a star’s habitable zone. Water is a key ingredient for life, and on a planet too close to its star, water on its surface may “boil”; too far, and it could freeze. This zone marks the region in between. But being in this sweet spot doesn’t automatically mean a planet is hospitable to life. Other factors, like whether a planet is geologically active or has processes that regulate gases in its atmosphere, play a role. The habitable zone provides a useful guide to search for signs of life on exoplanets – planets outside our solar system orbiting other stars. But what’s in these planets’ atmospheres holds the next clue about whether liquid water — and possibly life — exists beyond Earth. On Earth, the greenhouse effect, caused by gases like carbon dioxide and water vapor, keeps the planet warm enough for liquid water and life as we know it. Without an atmosphere, Earth’s surface temperature would average around zero degrees Fahrenheit (minus 18 degrees Celsius), far below the freezing point of water. The boundaries of the habitable zone are defined by how much of a “greenhouse effect” is necessary to maintain the surface temperatures that allow for liquid water to persist. It’s a balance between sunlight and atmospheric warming. Many planetary scientists, including me, are seeking to understand if the processes responsible for regulating Earth’s climate are operating on other habitable zone worlds. We use what we know about Earth’s geology and climate to predict how these processes might appear elsewhere, which is where my geoscience expertise comes in.Picturing the habitable zone of a solar system analog, with Venus- and Mars-like planets outside of the ‘just right’ temperature zone.NASA
Why the habitable zone?
The habitable zone is a simple and powerful idea, and for good reason. It provides a starting point, directing astronomers to where they might expect to find planets with liquid water, without needing to know every detail about the planet’s atmosphere or history. Its definition is partially informed by what scientists know about Earth’s rocky neighbors. Mars, which lies just outside the outer edge of the habitable zone, shows clear evidence of ancient rivers and lakes where liquid water once flowed. Similarly, Venus is currently too close to the Sun to be within the habitable zone. Yet, some geochemical evidence and modeling studies suggest Venus may have had water in its past, though how much and for how long remains uncertain. These examples show that while the habitable zone is not a perfect predictor of habitability, it provides a useful starting point.
Planetary processes can inform habitability
What the habitable zone doesn’t do is determine whether a planet can sustain habitable conditions over long periods of time. On Earth, a stable climate allowed life to emerge and persist. Liquid water could remain on the surface, giving slow chemical reactions enough time to build the molecules of life and let early ecosystems develop resilience to change, which reinforced habitability. Life emerged on Earth, but continued to reshape the environments it evolved in, making them more conducive to life. This stability likely unfolded over hundreds of millions of years, as the planet’s surface, oceans and atmosphere worked together as part of a slow but powerful system to regulate Earth’s temperature. A key part of this system is how Earth recycles inorganic carbon between the atmosphere, surface and oceans over the course of millions of years. Inorganic carbon refers to carbon bound in atmospheric gases, dissolved in seawater or locked in minerals, rather than biological material. This part of the carbon cycle acts like a natural thermostat. When volcanoes release carbon dioxide into the atmosphere, the carbon dioxide molecules trap heat and warm the planet. As temperatures rise, rain and weathering draw carbon out of the air and store it in rocks and oceans. If the planet cools, this process slows down, allowing carbon dioxide, a warming greenhouse gas, to build up in the atmosphere again. This part of the carbon cycle has helped Earth recover from past ice ages and avoid runaway warming. Even as the Sun has gradually brightened, this cycle has contributed to keeping temperatures on Earth within a range where liquid water and life can persist for long spans of time. Now, scientists are asking whether similar geological processes might operate on other planets, and if so, how they might detect them. For example, if researchers could observe enough rocky planets in their stars’ habitable zones, they could look for a pattern connecting the amount of sunlight a planet receives and how much carbon dioxide is in its atmosphere. Finding such a pattern may hint that the same kind of carbon-cycling process could be operating elsewhere. The mix of gases in a planet’s atmosphere is shaped by what’s happening on or below its surface. One study shows that measuring atmospheric carbon dioxide in a number of rocky planets could reveal whether their surfaces are broken into a number of moving plates, like Earth’s, or if their crusts are more rigid. On Earth, these shifting plates drive volcanism and rock weathering, which are key to carbon cycling.Simulation of what space telescopes, like the Habitable Worlds Observatory, will capture when looking at distant solar systems.STScI, NASA GSFC
Keeping an eye on distant atmospheres
The next step will be toward gaining a population-level perspective of planets in their stars’ habitable zones. By analyzing atmospheric data from many rocky planets, researchers can look for trends that reveal the influence of underlying planetary processes, such as the carbon cycle. Scientists could then compare these patterns with a planet’s position in the habitable zone. Doing so would allow them to test whether the zone accurately predicts where habitable conditions are possible, or whether some planets maintain conditions suitable for liquid water beyond the zone’s edges. This kind of approach is especially important given the diversity of exoplanets. Many exoplanets fall into categories that don’t exist in our solar system — such as super Earths and mini Neptunes. Others orbit stars smaller and cooler than the Sun. The datasets needed to explore and understand this diversity are just on the horizon. NASA’s upcoming Habitable Worlds Observatory will be the first space telescope designed specifically to search for signs of habitability and life on planets orbiting other stars. It will directly image Earth-sized planets around Sun-like stars to study their atmospheres in detail.NASA’s planned Habitable Worlds Observatory will look for exoplanets that could potentially host life. Instruments on the observatory will analyze starlight passing through these atmospheres to detect gases like carbon dioxide, methane, water vapor and oxygen. As starlight filters through a planet’s atmosphere, different molecules absorb specific wavelengths of light, leaving behind a chemical fingerprint that reveals which gases are present. These compounds offer insight into the processes shaping these worlds. The Habitable Worlds Observatory is under active scientific and engineering development, with a potential launch targeted for the 2040s. Combined with today’s telescopes, which are increasingly capable of observing atmospheres of Earth-sized worlds, scientists may soon be able to determine whether the same planetary processes that regulate Earth’s climate are common throughout the galaxy, or uniquely our own. Morgan Underwood, Ph.D. Candidate in Earth, Environmental and Planetary Sciences, Rice University This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Chris Impey, University Distinguished Professor of Astronomy, University of Arizona This article is republished from The Conversation under a Creative Commons license. Read the original article.
