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

Does our Solar System have 9 planets or only 8? Astronomers have gone back and forth on that a lot, with Pluto now being classified as a dwarf planet. However, out beyond Neptune there could be ...

In February 2025, all seven of our planetary neighbors will be visible from Earth. So what does such a planetary alignment ...

A planet-size object that possibly once visited the solar system may have permanently changed our cosmic neighborhood by warping the orbits of the four outer planets, a new study suggests.

That path is called the ecliptic, and it exists because all planets in our solar system orbit around the sun on roughly the same plane. Astronomers, on the other hand, look for more specific ...