New measurements of the mass of Saturn's rings reveal their age — and something they have in common with dinosaurs.

Data from NASA's New Horizons spacecraft, which explored Kuiper Belt object Ultima Thule earlier this week, is yielding scientific discoveries daily.

Images of the Kuiper Belt object Ultima Thule unveil the very first stages of solar system's history.

NASA's New Horizons spacecraft flew past Ultima Thule in the early hours of New Year's Day, ushering in the era of exploration from the enigmatic Kuiper Belt.

A message from Thomas Zurbuchen, the associate administrator of NASA's Science Missions Directorate, to Alan Stern, New Horizons principal investigator of the Southwest Research Institute in Boulder, Colorado.

On December 31, NASA's OSIRIS-REx spacecraft entered into orbit around the asteroid Bennu, and made Bennu the smallest object ever to be orbited by a spacecraft.

Closest approach takes place in the early morning hours of New Year's Day—12:33 a.m. EST—marking the most distant close exploration of worlds ever completed by humankind.

A schedule of events surrounding the New Horizons flyby of Kuiper Belt Object MU69.

Without Hubble's intriguing early images, there might have never been a mission to explore Pluto and the Kuiper Belt.

From its brightness and size, New Horizons team members have calculated Ultima's reflectivity, which is only about 10 percent, or about as dark as garden dirt. Beyond that, nothing else is known about it.

NASA's Lucy spacecraft will fly by six asteroid targets, each in different orbits, over the course of 12 years.

The asteroid will fly safely past Earth on Saturday, Dec. 22, at a distance of about 1.8 million miles (2.9 million kilometers).