WD 1856+534b—a freezing world with a surface temperature of -125 degrees Fahrenheit—exists where planets are normally scoured ...

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

While Mercury is often associated with havoc-wreaking retrogrades, the messenger planet deserves more credit for coloring our ...

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and then the possible Planet Nine. It's a dynamic system shaped by gravity and time, and while we've learned a lot, it still holds ...