Using two infrared space telescopes and a 23-year gap, scientists may have spotted a mysterious, slow-moving object beyond ...

Researchers have found a candidate for the hypothetical Planet Nine, which could be an undiscovered giant planet way out in ...

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

The 950-foot hunk of primordial matter is classified as a "potentially hazardous asteroid," but that doesn't mean it has a ...

If the object really is Planet Nine, it would be larger than Neptune and exist 700 times further from the sun than Earth.

This is probably the most convincing evidence for Planet Nine so far. It is believed that this planet is five to ten times ...

A ninth planet the size of Neptune may be hidden in the far reaches of the solar system, but the evidence has left some experts skeptical.

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

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

The presence of another planet in the solar system could explain the odd movements of some of the bodies in the Kuiper Belt.

Astronomers have long speculated about an unseen planet lurking in the solar system's outer edge. This hypothetical world, ...

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