Astronomers have spotted helium escaping from the atmosphere of an exoplanet, LHS 1140c, orbiting a red dwarf star. This finding suggests how planetary atmospheres can evolve over billions of years.

The study, published in Nature, reveals that hydrogen and helium are often lost to space due to radiation pressure, even though gravity tries to hold them back. Venus, Earth and Mars may also have once had similar atmospheres before losing their lighter elements.

What's unique about LHS 1140c is its proximity to the star; it takes just over three days to complete an orbit. This intense radiation could explain why helium is escaping so quickly from its atmosphere, unlike hydrogen which can be trapped in molecules like methane and ammonia.

The dynamics of atmospheric loss are complex, involving factors such as a planet's distance from its star, the strength of its magnetic field, and its gravitational pull. Understanding these processes helps us predict how other exoplanets might evolve over time.

This research could provide insights into our own atmosphere's future, especially if humans continue to rely on fossil fuels. As Earth warms and radiation increases, could we face similar atmospheric changes? Only time—and science—will tell.