It's been one Neptunian year—or about 165 Earth years—since astronomers first observed the most distant planet from the sun.

Because the solar system's contents formed from a disk around the sun, we would expect the orbits of everything orbiting the sun to keep relatively close to the plane of that disk. However, some don’t ...

Astronomers have unexpectedly discovered the heaviest Neptune-like planet yet — one more than four times the mass of our solar system's Neptune — yet it remains a mystery how the world might have ...

In 1989, Voyager 2 became the first and only spacecraft to ever fly by Neptune, and images from that mission famously show a planet that's a deep azure color. But in reality, Neptune is far more of a ...

Nearly a century after Pluto’s discovery, astronomers are still hunting for mysterious planets beyond Neptune - including a ...

An enigmatic, cloud-enshrouded planet that has puzzled astronomers for years turns out to be less hot than expected – and surprisingly shiny. That's what the James Webb Space Telescope revealed when ...

Mars lies well to the left (east) of the planetary duo of Jupiter and Saturn and stands about three fists high in the southeastern sky at early dawn. To see all three planets best be out around an ...

Mercury, the planet of communication and thought, began its retrograde in Sagittarius on November 9, spotlighting truth, ...

Artist’s concept of a Neptune-sized planet, left, around a blue, A-type star. UC Berkeley astronomers have discovered a hard-to-find gas giant around one of these bright, but short-lived, stars, right ...

A planet's year length depends on its distance from the Sun. Planets closer to the Sun have shorter years. A planet's rotation speed is unrelated to its year length. Planets' orbital speeds vary ...