An international team of astronomers using the CHEOPS space telescope presents a striking discovery about exoplanet LTT9779b. The planet appears to rain molten titanium, and it shows the highest reflectivity observed beyond our solar system. The researchers published their findings in Astronomy and Astrophysics, sharing a view into a world where metals may play a visible role in the atmosphere.
Roughly Neptune-sized, LTT9779b lies about 260 light-years away from Earth. It reflects up to 80 percent of the starlight that reaches it, making it one of the brightest exoplanets observed from our vantage point. This extreme albedo is tied to the planet’s scorching conditions and the peculiar make-up of its upper atmosphere, where metals can influence how light is scattered and reflected back into space.
The planet orbits very close to its host star, completing a rotation in just 19 hours. In this tight configuration, scientists note that beyond gas giants, rocky worlds were once the usual closest neighbors around bright stars. LTT9779b challenges that expectation by presenting a heat-drenched environment that still supports a complex, observable atmosphere.
Daytime temperatures on LTT9779b reach around 2,000 degrees Celsius, a heat level that would normally prevent cloud formation. Nevertheless, astronomers are detecting atmospheric signatures that imply cloud structures do exist, albeit in unusual forms. The prevailing interpretation is that the intense warmth drives melting and evaporation of metals and silicates, injecting vapor that oversaturates the atmosphere and leads to the formation of metal-rich clouds. This gives researchers a rare glimpse into cloud chemistry under extreme conditions and helps explain the observed reflectivity.
Earlier observations have revealed multiple Neptune-sized exoplanets, underscoring a growing class of distant worlds that challenge traditional models of planet formation and atmospheric dynamics. The latest measurements of LTT9779b add a new data point to this category, illustrating how a planet can be both incredibly hot and highly reflective at the same time, and how its atmosphere can remain observable in such a violent environment. The CHEOPS mission continues to provide high-precision photometry that enables these insights, helping scientists to map the complex interplay between a planet’s surface, its atmospheric composition, and the bright light of its star.