The planet TRAPPIST-1e lies in its star’s Goldilocks zone, where water remains liquid – and an analysis suggests it might have a nitrogen-rich atmosphere like Earth’s
By Matthew Sparkes
8 September 2025
Artist’s impression of the planet TRAPPIST-1e
NASA/JPL-Caltech
There are promising signs that one of the planets in the TRAPPIST-1 star system, which lies about 40 light years from Earth, has an atmosphere capable of supporting life. But scientists will need to image it 15 times more to make sure.
TRAPPIST-1 is a small red dwarf star with at least seven planets. It was discovered in 2016 and immediately became a target for astronomers hoping to detect extraterrestrial life because three of its planets lie within the so-called Goldilocks zone where water remains liquid.
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Ryan MacDonald at the University of St Andrews, UK, says TRAPPIST-1 caused a huge amount of excitement among astronomers after its discovery. However, subsequent imaging of three of its exoplanets, including two of the three within the Goldilocks zone, left the field disappointed when no atmosphere was detected around any of them. But he and colleagues have long been focused on TRAPPIST-1e, right in the middle of the Goldilocks zone, and now believe they have reason for optimism.
MacDonald and his colleagues used the James Webb Space Telescope to scan TRAPPIST-1e in 2023 and have been working since then to extract a better picture of the world. Astronomers gather information on whether a distant exoplanet has an atmosphere by capturing images of the world as it passes in front of its star. Analysing subtle alterations to the starlight can reveal which chemicals are present in any atmosphere – and whether they include those that may be conducive to life.
But because TRAPPIST-1 is a red dwarf, it is much cooler than our own sun, making the readings more complex. For instance, chemicals like water that could indicate a hospitable atmosphere might actually be present in the star itself, meaning that signatures from TRAPPIST-1e’s atmosphere had to be disentangled from those of the TRAPPIST-1 starlight that was shining through it. This demanded new models and years of work. The preliminary results are now in and they suggest TRAPPIST-1e has a life-friendly atmosphere, potentially marking a significant moment in the search for habitable conditions for life beyond Earth.