Astrophysicists propose new methods to detect exoplanet oceans and atmospheres

Researchers are developing new methods to identify liquid oceans on distant exoplanets and understand how certain worlds retain their atmospheres.

A study from the University of Arizona suggests that astronomers could detect oceans by observing “glint,” or specular reflection. Unlike rocky or sandy surfaces that scatter light in all directions, water acts like a mirror at shallow angles. When an exoplanet is in its crescent phase, starlight hitting an ocean could reflect directly into telescopes, causing a dramatic increase in brightness. This phenomenon has previously been observed on Saturn's moon Titan and Earth.

Separately, Stanford University researchers have proposed a model to explain why some lava-covered planets near their stars retain thick atmospheres despite intense stellar radiation. The study, published in The Astrophysical Journal Letters, introduces the concept of a “cosmic sandbar.” This model suggests that molten surfaces can regulate the release of gases from a planet’s interior, allowing atmospheric replenishment to keep pace with losses. This finding expands the known “cosmic shoreline,” the boundary that traditionally separates rocky worlds capable of holding atmospheres from those that cannot.