This discovery marks the first known case of a compact planetary system with such a noticeable tilt between close planet ...

Artist's impression of Planet Nine – a suspected “wide-orbit” planet – with the Sun in the distance; Neptune's orbit is shown ...

Stars often whip their planets with solar winds and radiation, pull them ever closer with gravity and sear them with heat.

But an international team of astronomers have detected the unmistakable signature of a gas giant planet orbiting the ...

For the dwarf planet candidate, one trip around the sun takes over 24,000 years. Its orbit challenges a proposed path for a hypothetical Planet Nine.

A dwarf planet is "classified as a celestial body that orbits the sun that has enough mass and gravity to be mostly round, but unlike other planets, has not cleared its orbital path of asteroids and ...