atmospheres Archives

February 3, 2024February 3, 2024 by Brian Koberlein

Atmospheres in the TRAPPIST-1 System Should be Long Gone

Illustration of the Trappist-1 system. Credit: NASA/JPL-Caltech

Trappist-1 is a fascinating exoplanetary system. Seven worlds orbiting a red dwarf star just 40 light-years away. All of the worlds are similar to Earth in mass and size, and 3 or 4 of them are potentially habitable. Imagine exploring a system of life-rich worlds within easy traveling distance of each other. It’s a wonderful dream, but as a new study shows it isn’t likely that life exists in the system. It’s more likely the planets are barren and stripped of their atmospheres.

January 17, 2023January 17, 2023 by Evan Gough

Worlds Bustling With Plantlife Should Shine in a Detectable Wavelength of Infrared

Artist's rendering of a super-Earth-type exoplanet, TOI 1452 b. Credit: Benoit Gougeon, Université de Montréal.

Future historians might look back on this time and call it the ‘exoplanet age.’ We’ve found over 5,000 exoplanets, and we’ll keep finding more. Next, we’ll move beyond just finding them, and we’ll turn our efforts to finding biosignatures, the special chemical fingerprints that living processes imprint on exoplanet atmospheres.

But there’s more to biosignatures than atmospheric chemistry. On a planet with lots of plant life, light can be a biosignature, too.

October 18, 2022October 18, 2022 by Evan Gough

Scientists Discover a New Way Exoplanets Could Make Oxygen; Unfortunately, it Doesn’t Require Life

Oxygen is a valuable biosignature because Earth is oxygen-rich, and because life made all that oxygen. But if we find oxygen in an exoplanet atmosphere does that mean life made it? Or is there an abiotic source of oxygen? Image Credit: NASA

Finding oxygen in an exoplanet’s atmosphere is a clue that life may be at work. On Earth, photosynthetic organisms absorb carbon dioxide, sunlight, and water and produce sugars and starches for energy. Oxygen is the byproduct of that process, so if we can detect oxygen elsewhere, it’ll generate excitement. But researchers have also put pressure on the idea that oxygen in an exoplanet’s atmosphere indicates life. It’s only evidence of life if we can rule out other pathways that created the oxygen.

But scientists can’t rule them out.

March 31, 2022March 31, 2022 by Evan Gough

It’s Not Conclusive, But Methane is Probably the Best Sign of Life on Exoplanets

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. Scientists could use this one or one like it to measure planetary entropy production as a prelude to exploration. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

When the James Webb Space Telescope aims at exoplanet atmospheres, it’ll use spectroscopy to identify chemical elements. One of the things it’s looking for is methane, a chemical compound that can indicate the presence of life.

Methane is a compelling biosignature. Finding a large amount of methane in an exoplanet’s atmosphere might be our most reliable indication that life’s at work there. There are abiotic sources of methane, but for the most part, methane comes from life.

But to understand methane as a potential biosignature, we need to understand it in a planetary context. A new research letter aims to do that.

March 15, 2022March 15, 2022 by Evan Gough

Smaller, Ground-Based Telescopes can Study Exoplanet Atmospheres too

An artist's illustration of exoplanet Kelt-9b. Image Credit: NASA/JPL-Caltech

The next step to understanding exoplanets is to understand their atmospheres better. Astronomers can determine a planet’s mass, density, and other physical characteristics fairly routinely. But characterizing their atmospheres is more complicated.

Astronomers have had some success studying exoplanet atmospheres, and spacecraft like the James Webb Space Telescope and the ESA’s ARIEL mission will help a lot. But there are thousands of confirmed exoplanets with many more to come, and the Webb has many demands on its time.

Can smaller, ground-based telescopes play a role in understanding exoplanet atmospheres?

February 8, 2022February 8, 2022 by Brian Koberlein

Why are Neptune and Uranus Different Colors?

A comparison of Uranus (left) and Neptune (right). Credit: Left: NASA/JPL-Caltech, Right: NASA

Uranus and Neptune are similar planets in many ways. Both are ice giant worlds, both have atmospheres rich in methane, and both have a bluish color. But while Uranus has a pale blue-green hue, Neptune has a deep blue color. But why? Why would two planets so similar in size and composition appear so different? According to a recent study, the answer lies in their aerosols.

January 8, 2021January 8, 2021 by Evan Gough

Stellar Flares May Not Condemn a Planet’s Habitability

An artistic rendering of a series of powerful stellar flares. New research says that flaring activity may not prevent life on exoplanets. CREDIT NASA's Goddard Space Flight Center/S. Wiessinger

Red dwarf stars are the most common kind of star in our neighbourhood, and probably in the Milky Way. Because of that, many of the Earth-like and potentially life-supporting exoplanets we’ve detected are in orbit around red dwarfs. The problem is that red dwarfs can exhibit intense flaring behaviour, much more energetic than our relatively placid Sun.

So what does that mean for the potential of those exoplanets to actually support life?

October 13, 2020October 13, 2020 by Evan Gough

An Exoplanet So Hot There Are 7 Different Kinds of Gaseous Metals in its Atmosphere

This artist's illustration shows an alien world that is losing magnesium and iron gas from its atmosphere. The observations represent the first time that so-called "heavy metals"—elements more massive than hydrogen and helium—have been detected escaping from a hot Jupiter, a large gaseous exoplanet orbiting very close to its star. The planet, known as WASP-121b, orbits a star brighter and hotter than the Sun. Image Credit: NASA, ESA, and J. Olmsted (STScI)

The search for exoplanets has revealed types of planets that are nothing like the worlds in our own Solar System. One such type is the hot-Jupiter. They’re gas giants like Jupiter that orbit their host star very closely. That proximity raises their temperatures to extreme heights.

Hot-Jupiters can be hot enough to vaporize metals, making their atmospheres un-Earthlike. A team of astronomers examining one exoplanet has found 7 different gaseous metals in its atmosphere.

September 17, 2020September 17, 2020 by Evan Gough

James Webb Will Look for Signs of Life on Planets Orbiting Dead Stars

A planet orbiting a small star produces strong atmospheric signals when it passes in front, or “transits,” its host star, as pictured above. White dwarfs offer astronomers a rare opportunity to characterize rocky planets. Image Credit: Jack Madden/Carl Sagan Institute

Can the galaxy’s dead stars help us in our search for life? A group of researchers from Cornell University thinks so. They say that watching exoplanets transit in front of white dwarfs can tell us a lot about those planets.

It might even reveal signs of life.

May 28, 2020May 28, 2020 by Evan Gough

Extremely Hot Exoplanets Can Have Extreme Weather, Like Clouds of Aluminum Oxide and Titanium Rain

Thi illustration of a Hot Jupiter orbiting close to its star. Image Credit: ESA/ATG medialab, CC BY-SA 3.0 IGO

Thanks to the success of the Kepler mission, we know that there are multitudes of exoplanets of a type called “Hot Jupiters.” These are gas giants that orbit so close to their stars that they reach extremely high temperatures. They also have exotic atmospheres, and those atmospheres contain a lot of strangeness, like clouds made of aluminum oxide, and titanium rain.

A team of astronomers has created a cloud atlas for Hot Jupiters, detailing which type of clouds and atmospheres we’ll see when we observe different Hot Jupiters.