Compared with other known planetary systems, the solar system contains an unusually high number of planets. In total, there are 812 known planetary systems with three or more confirmed planets ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy ... Objects need to be at least 400 km or so in size to round out via self-gravity, ...

This limits the number of concentric orbital planes you can have around a star before a system becomes unstable. He found that, theoretically, a Sun-like star could support 42 planets in a single ...

Rogue planets that range from Mars mass to Earth mass will be future targets for the Roman telescope. As they cross in front of a star and bend spacetime (therefore bending the star’s light ...

This month, both the TRAPPIST and Kepler planet-hunting telescopes have announced the discovery of multiple near-Earth-sized planets orbiting M dwarf stars, some within the habitable zones.

A new theory suggests that if life was possible on Super-Earth planets, gravity may be holding aliens back from leaving. ... This would limit the number of flights that could be sent to space.

At the same time, our two planets are really quite different, and in a number of very important ways. One of these is the fact that gravity on Mars is just a fraction of what it is here on Earth ...