“This would be the first time that we can directly show through an atmospheric detection, that these planets with water-rich atmospheres can actually exist around other stars…This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets.”
–Statement by Björn Benneke of the Trottier Institute for Research on Exoplanets at Université de Montréal. He was referring to the Hubble space telescope’s detection of water vapor in the atmosphere of exoplanet GJ 9827d. The exoplanet is about twice the Earth’s diameter and approximately 97 light-years from Earth. You can read more about the Hubble discovery here.
Once upon a cosmic time, scientists assumed that stars apply an eternal magnetic brake, causing an endless slowdown of their rotation. With new observations and sophisticated methods, they have now peeked into a star’s magnetic secrets and found that they are not what they expected. The cosmic hotspots for finding alien neighbors might be around stars hitting their midlife crisis and beyond. This groundbreaking study, shedding light on magnetic phenomena and habitable environments, has been published in The Astrophysical Journal Letters.
In a system with two known planets, astronomers spotted something new: a small object transiting across the Sun-sized star. This turned out to be another planet: extra hot and Earth-sized…The newly-spotted planet, called HD 63433 d, is tidally locked, meaning there is a dayside which always faces its star and a side that is constantly in darkness. This exoplanet, or planet outside of our solar system, orbits around the star HD 63433 (TOI 1726) in the HD 63433 planetary system. This scorching world is the smallest confirmed exoplanet younger than 500 million years old. It’s also the closest discovered Earth-sized planet this young, at about 400 million years old.
Does the size of an exomoon help determine if life could form on an exoplanet it’s orbiting? This is something a February 2022 study published in Nature Communications hopes to address as a team of researchers investigated the potential for large exomoons to form around large exoplanets (Earth-sized and larger) like how our Moon was formed around the Earth. Despite this study being published almost two years ago, its findings still hold strong regarding the search for exomoons, as astronomers have yet to confirm the existence of any exomoons anywhere in the cosmos. But why is it so important to better understand the potential for large exomoons orbiting large exoplanets?
Image (Credit): Chart showing the planned travel of the JUICE spacecraft. (ESA, work performed by ATG under contract to ESA)
I wanted to start out the new year by first remembering all of the great missions from 2023. I also decided to group this work rather than focus on single missions.
NASA Asteroid Missions: Asteroids were the big news this year, with Lucy encountering a surprise pair of asteroids, OSIRIS-REx bringing back a sample from the asteroid Bennu, and NASA launching the Psyche mission.
JWST Discoveries: This year we celebrated the anniversary of the James Webb Space Telescope (JWST), which has been better than ever imaged. It is helping to change our understanding of the origin of the universe while poking and prodding at exoplanets to review their secrets.
ESA Missions: The European Space Agency (ESA) has also been very busy in 2023. For instance, the launch of the Euclid mission to study dark matter and dark energy, as well as the JUICE mission to study Jupiter and its moons, will assist with our understanding of the big picture as well as our own neighborhood.
That’s an impressive record, and I look forward to even more great news in 2024.
The conventional observables to identify a habitable or inhabited environment in exoplanets, such as an ocean glint or abundant atmospheric O2, will be challenging to detect with present or upcoming observatories. Here we suggest a new signature. A low carbon abundance in the atmosphere of a temperate rock`y planet, relative to other planets of the same system, traces the presence of a substantial amount of liquid water, plate tectonics and/or biomass. Here we show that JWST can already perform such a search in some selected systems such as TRAPPIST-1 via the CO2 band at 4.3 μm, which falls in a spectral sweet spot where the overall noise budget and the effect of cloud and/or hazes are optimal. We propose a three-step strategy for transiting exoplanets: detection of an atmosphere around temperate terrestrial planets in about 10 transits for the most favourable systems; assessment of atmospheric carbon depletion in about 40 transits; and measurements of O3 abundance to disentangle between a water- versus biomass-supported carbon depletion in about 100 transits. The concept of carbon depletion as a signature for habitability is also applicable for next-generation direct-imaging telescopes.
Citation: Triaud, A.H.M.J., de Wit, J., Klein, F. et al. Atmospheric carbon depletion as a tracer of water oceans and biomass on temperate terrestrial exoplanets. Nat Astron (2023). https://doi.org/10.1038/s41550-023-02157-9
Archive footage of space rockets taking off beam across giant walls in a new immersive show in London, as Hollywood actor Tom Hanks narrates the story of human voyages to the moon. “The Moonwalkers: A Journey With Tom Hanks” looks at the first moon landings of the Apollo missions from 1969 to 1972 and their successor, NASA’s human spaceflight program, Artemis. The next mission – the Artemis II lunar flyby – is planned for next year and interviews with the four-member team are also projected on the walls at the Lightroom gallery space in London’s King Cross area.
Just as it can be assumed that the stars in our Milky Way are orbited by planets, moons around these exoplanets should not be uncommon. This makes it all the more difficult to detect them. So far, only two of the more than 5300 known exoplanets have been found to have moons. A new data analysis now demonstrates that scientific statements are rarely black or white, that behind every result there is a greater or lesser degree of uncertainty and that the path to a statement often resembles a thriller. In observations of the planets Kepler-1625b and Kepler-1708b from the Kepler and Hubble space telescopes, researchers had discovered traces of such moons for the first time. A new study now raises doubts about these previous claims. As scientists from the Max Planck Institute for Solar System Research and the Sonnenberg Observatory, both in Germany, report in the journal Nature Astronomy, “planet-only” interpretations of the observations are more conclusive.
Human beings first disturbed moon dust Sept. 13, 1959, when the USSR’s unmanned spacecraft Luna 2 alighted on the lunar surface. In the following decades, more than a hundred other spacecraft have touched the moon — both crewed and uncrewed, sometimes landing and sometimes crashing. The most famous of these were NASA’s Apollo Lunar Modules, which transported humans to the moon’s surface to the astonishment of humankind. In the coming years, missions and projects already planned will change the face of the moon in more extreme ways. Now, according to anthropologists and geologists at the University of Kansas, it’s time to acknowledge humans have become the dominant force shaping the moon’s environment by declaring a new geological epoch for the moon: the Lunar Anthropocene.
