Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

Earth has four seasons, but do other planets in our solar system also have hot summer days and cold winter nights?

At the center is the sun, a yellow dwarf star that contains 99.8% of the solar system's mass. Everything else — from the eight major planets to dwarf planets, comets, asteroids, and icy objects ...

Discovered in 1930, Pluto was long considered our Solar System's ninth planet, but was unseated in 2006 after the discovery ...

For over a century, astronomers have wondered if there's an extra planet in our Solar System that we haven't been able to see ...

For years, astronomers have toyed with the idea that the Sun hides an extra planet so distant and dim that even the best ...

Astronomer Eliza Kempton said that she had waited her "entire career" to peer into an atmosphere from this mysterious class of planets.

A new look through decades-old data has unveiled some of the most compelling evidence yet of a hidden ninth planet in the far ...

Pluto was discovered in 1930 in Arizona, but in 2006 scientists decided to cut Pluto from the planetary line up. Here is why ...

The solar system consists of our star, the sun, and everything bound to it by gravity: the planets Mercury, Venus, Earth, ...

Astronomers may have found a candidate for Planet Nine. This planet is beyond Neptune. The finding could be the first ...

Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about ...