The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

HD 20794 d completes its orbit just shy of two Earth years, placing it well within reach of conditions that might harbor life ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

When you first learned about the Solar System, you probably saw diagrams that made it look orderly, with planets arranged in ...

A new study suggests that a close encounter with a massive interstellar object, possibly eight times the mass of Jupiter, may ...

A new study claims it is possible an "alien visitor" could have warped our solar system during its earliest years.

Beyond Neptune lies the Kuiper Belt, a vast expanse of icy bodies that may hold clues to the solar system’s formation. These ...

Ever since Isaac Newton famously talked about gravity, its dominance as a force in our solar system has been well known. It's ...

Our Solar System is a carefully balanced celestial dance held together by a virtually perfect balance of gravity and inertia.

may have significantly altered the orbits of the four outer planets in our solar system. This encounter, occurring billions of years ago, could explain the slight deviations from ideal circular ...