A planet-size object that possibly once visited the solar system may have permanently changed our cosmic neighborhood by ...

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

Astronomers have discovered six planets orbiting a bright star in perfect resonance. The star system, 100 light-years from Earth, was described on Wednesday in a paper published in the journal ...

Using computer models of the four outer planets, the team carried out 50,000 simulations of such flybys, each over 20 million years, while altering certain parameters of each visitor, ...

Using computer models of the four outer planets, the team carried out 50,000 simulations of such flybys, each over 20 million years, while altering certain parameters of each visitor, including ...