"It's incredible to be able to make these kinds of discoveries," said researcher David Armstrong.
"These selected missions have the potential to transform our understanding of some of the solar system's most active and complex worlds," NASA's Thomas Zurbuchen said.
Two of Neptune's inner moons are locked together in a type of orbit that has not been seen before. This allows them to cross paths without coming into contact, researchers say.
The planet is the first of its kind to be discovered in the "Neptunian Desert"—the region immediately surrounding stars where no planets similar in size to Neptune are found.
Months after Russia seized three Ukrainian navy ships in the Sea of Azov, the project is more relevant than ever.
The planets face supernovas, gamma-ray bursts and gravity-disrupting stars in the crowded center of the Milky Way.
The storm could smell like rotten eggs, according to scientists.
Neptune and Uranus could have thin exterior shells of liquid water and thick interior mantles of superionic ice water.
Dry your eyes and grab your binoculars. There's still plenty to see.
The discovery of a small, icy world is raising questions about the entire prospect of a ninth planet.
The planet is believed to be 5,000 times the mass of Pluto.
Astrophysicists cite orbit patterns, but some critics are not yet ready to believe.