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

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

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 ...

NASA's Lucy will venture as close as 596 miles to this asteroid, an estimated 2 ½ miles in length but much shorter in width.