Imagine looking up at the night sky and pondering the existence of alien oceans on distant worlds. Well, that might not be purely sci-fi anymore. Thanks to the James Webb Space Telescope (JWST), scientists have uncovered compelling evidence that a distant exoplanet called LHS 1140 b might harbor liquid water – potentially even an entire ocean. This riveting discovery has set astronomers’ hearts ablaze as they edge closer to answering one of humanity’s oldest questions: are we alone in the universe?
LHS 1140 b isn’t just any exoplanet. Found about 48 light-years away in the constellation Cetus, this world is more massive than Earth, scaling at 1.7 times Earth’s size and 5.6 times its mass. Interestingly, it orbits a red dwarf star that's cooler and smaller than our sun, making LHS 1140 b a premier candidate for habitability. In contrast to formerly held beliefs labeling it a mini-Neptune, recent observations suggest it might be a “super-Earth” with significant amounts of liquid water or even an icy substellar ocean.
To offer some backstory, LHS 1140 b was first discovered in 2017. Initial observations had scientists classify it as a mini-Neptune, assuming it had a thick atmosphere comprising hydrogen and helium. But the haze cleared up significantly with new JWST data. Researchers now propose that the exoplanet is icier and wetter, thus more likely to be habitable.
“Of all currently known temperate exoplanets, LHS 1140 b could well be our best bet to one day indirectly confirm liquid water on the surface of an alien world beyond our solar system,” says Charles Cadieux, an astrophysicist involved in the study.
The star at the heart of LHS 1140 b’s system is a red dwarf, smaller and cooler compared to our sun. This classification is key because it places the exoplanet within the ‘Goldilocks zone’ – the ideal distance from its star where conditions are neither too hot nor too cold and liquid water can potentially exist. On Earth, liquid water is essential for life; therefore, finding it on an exoplanet boosts its odds of being habitable.
You might wonder how researchers arrived at such a conclusion. They used JWST’s Near-Infrared Imager and Slitless Spectrograph to observe the planet. Light from the star passes through the planet’s atmosphere before reaching JWST, allowing scientists to discern the chemicals present. Observations revealed traces of nitrogen, akin to Earth’s atmosphere. Remarkably, the density measurements indicate it isn’t rocky but rather covered by an icy expanse. Calculations further propose that about 10-20% of its mass could be water.
The intriguing “eyeball” theory about LHS 1140 b has also gained traction. In this model, the side of the planet facing the star is warm enough to sustain liquid water, forming an iris-like ocean, while the far side remains frozen in perpetual darkness. This leads to a stark visual akin to an eyeball peering out into space.
Worlds like LHS 1140 b are captivating not just for their potential habitability, but also for what they teach us about planetary formation and climate. The idea that there could be a marine ecosystem in an alien world’s iris boggles the mind and turns science fiction into plausible future discoveries. In the quest for extraterrestrial life, such tantalizing finds set an optimistic stage for detailed future studies.
The JWST’s observations are relatively young, and much more data will be needed to paint a complete picture. “Detecting an Earth-like atmosphere on a temperate planet is pushing Webb's capabilities to its limits – it’s feasible; we just need lots of observing time,” explained René Doyon, one of the researchers. More observations are planned to confirm the presence of a nitrogen-rich atmosphere and to check for other vital gases like carbon dioxide. This makes LHS 1140 b an ideal candidate for continued study.
An exciting future lies ahead as researchers gear up to utilize every JWST opportunity to study this intriguing world. The potential discoveries from this mission could rewrite our understanding of exoplanets and their capacity to support life. Until we gather all the necessary data, the notion of an alien ocean glistening under an extraterrestrial sky remains one of the most exciting chapters in the search for life beyond Earth. As Cadieux pointedly stated, “This is a very promising start.”
