An Exoplanet Like No Other Yet Found

Of the 4,044 confirmed exoplanets found orbiting faraway stars, some are rocky like Earth, and others are gaseous like Jupiter. Some have thick atmospheres, others have none at all. Some planets hurtle around their stars in a matter of hours, while others can take decades to complete one orbit.

And then there’s K2-18b. It is about twice the size of Earth, but nearly nine times more massive. It orbits within its star’s habitable zone. And scientists just detected a hint of water in its atmosphere.

Astronomers have found water vapor in exoplanets before. But this distant world is the first known exoplanet that both shows signs of water