The atmosphere of the distant “warm Neptune” HAT-P-26b, illustrated here, is unexpectedly primitive, composed primarily of hydrogen and helium. By combining observations from NASA’s Hubble and Spitzer space telescopes, researchers determined that, unlike Neptune and Uranus, the exoplanet has relatively low metallicity, an indication of the how rich the planet is in all elements heavier than hydrogen and helium. | NASA/GSFC

Watery Atmosphere Discovered on Neptune-Like Exoplanet

The finding could provide an important breakthrough in understanding how planets form, and how atmospheres can vary between exoplanets with different masses.

May 11, 2017
2:31 PM EDT