Astronomers have unexpectedly discovered the heaviest Neptune-like planet yet — one more than four times the mass of our solar system's Neptune — yet it remains a mystery how the world might have ...

Warm Neptune-size exoplanets are not nearly as common as super-Earths or hot Jupiters — and we are now closer to finding out why. Our galaxy apparently has a dearth of Neptune-size worlds that orbit ...

Uranus and Neptune may not be the icy worlds we’ve long imagined. A new Swiss-led study uses innovative hybrid modeling to reveal that these planets could just as easily be dominated by rock as by ...