Dwarf planet

In 2006, Pluto was downgraded from planet to dwarf planet – and now, based on the same definition an object in the asteroid belt may need to be upgraded from asteroid to dwarf planet. New observations of asteroid Hygiea suggest it fits the criteria.

Astronomers are welcoming the newest and most distant object in the solar system – a dwarf planet orbiting more than 100 times further from the Sun than Earth. And because its discoverers aren’t the most creative bunch, it’s been dubbed “Farout.”

There could be thousands of dwarf planets – Pluto-sized or smaller – lurking at the very edges of the Sun’s influence. Now, astronomers have spotted a new distant dwarf with an incredibly wide orbit, lending further evidence to the idea that a much bigger “Planet X” is out there somewhere.

Pluto was demoted from planet status to dwarf planet in 2006. But a new study suggests it should be resurrected as a planet, since the definition the object failed to meet was not based on precedents set in scientific literature.

Evidence is growing for a ninth planet lurking on the edges of the Solar System. Objects out there move in ways that suggest an unseen world is pulling on them, but new calculations suggest that there is no Planet Nine – these distant objects might just be jostling each other like bumper cars.

Two new studies have used data gathered by NASA’s Dawn mission to determine that the dwarf planet Ceres’ salty, icy crust could be the remains of an ancient global ocean – and there may still be some liquid water locked up deep beneath the surface.

Astronomers have observed an occultation of a distant star to get a better look at the little-known dwarf planet Haumea, which orbits the Sun beyond Neptune. Scientists were able to pin down the planet’s size, shape and density, and make a surprising new discovery: Haumea has a rocky ring around it.

New data from NASA's Dawn spacecraft suggests that Ceres' surface is too strong to be dominated by ice.

​​NASA scientists have taken their first look at the interior of the dwarf planet Ceres, by tracking tiny alterations in the motion of the Dawn spacecraft as it continues to orbit the enigmatic planetoid.

A new dwarf planet has been identified on the fringes of our solar system. Designated 2015 RR245, the object’s size isn’t known just yet, but its discoverers estimate it to have a diameter of 700 km (435 miles) and one of the largest orbits of a dwarf planet, circling the Sun once every 700 years.

​​Using data collected by NASA's Dawn spacecraft, an international team of astronomers has created a Map of the dwarf planet Ceres' northern hemisphere detailing regions that exist in permanent shadow.

​Using data captured by NASA's New Horizons spacecraft, a team of researchers from Purdue University has estimated the depth of the vast nitrogen ice pool believed to exist beneath the Sputnik Planum region on the dwarf planet Pluto.