JWST Directly Images a Distant Exoplanet With Water Vapor in Its Atmosphere
Summary: On July 25, 2026, astronomers using JWST directly imaged a distant exoplanet with water vapor in its atmosphere, expanding the frontier of exoplanet atmospheric characterization.
In a landmark achievement for exoplanet science, the James Webb Space Telescope (JWST) has directly imaged a gas giant exoplanet and detected water vapor in its atmosphere — a first for a planet observed via direct imaging at such a large distance.
The exoplanet, designated YSES-1c, orbits a young Sun-like star called YSES-1 located approximately 309 light-years from Earth in the constellation Centaurus. The host star is only about 17 million years old, making it a valuable laboratory for studying planetary formation and early atmospheric evolution. YSES-1c is a super-Jupiter with a mass roughly 6 times that of Jupiter, orbiting at a projected separation of about 320 astronomical units (AU) — an extraordinarily wide orbit. At this distance the planet receives very little stellar radiation, and its effective temperature is estimated at around 800 Kelvin (~527°C).
Using the Mid-Infrared Instrument (MIRI) on JWST, the research team employed coronagraphy to block the overwhelming glare of the host star and isolate the faint infrared light emitted by the planet itself. MIRI's sensitivity in the mid-infrared range (roughly 5 to 28 microns) was critical, as water vapor has strong absorption features in this spectral region. Spectroscopic analysis revealed clear signatures of H₂O (water vapor) along with hints of other molecular species.
Lead author Dr. Kellen Lawson of NASA's Goddard Space Flight Center noted that this is exactly the kind of science JWST was built for — being able to directly capture the light from a planet's atmosphere and identify specific molecules like water vapor opens a new window into understanding how planetary atmospheres form and evolve. The research paper has been accepted for publication in The Astronomical Journal.