It is a question that feels like it should have a straightforward answer: how many planets are there in our solar system? Since Pluto was relegated back down to dwarf planet status, almost everyone ...

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

An artist's illustration of a possible ninth planet in our solar system, hovering at the edge of our solar system. Neptune's orbit is shown as a bright ring around the Sun. Scientists in Taiwan ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

WASHINGTON, May 30 (Reuters) - Scientists have identified an object about 435 miles (700 km) wide inhabiting the frigid outer reaches of our solar system that might qualify as a dwarf planet, spotting ...

Sheppard joined Carnegie as a prestigeous NASA Hubble Fellow in 2004 and was appointed to a faculty position in 2007. He ...