Planet 9 sits at the edge of scientific imagination, promising either an epic expansion of the Solar System or a lesson in how easily patterns can mislead us. As new data arrive and old assumptions ...

Learn how Pluto nearly kept its planet status in a proposed 12-planet Solar System as its demotion marks its 20th anniversary ...

The discovery of the Kuiper Belt revealed thousands of icy objects near Pluto, challenging its status as a planet. After the ...