The solar system lost its ninth planet back when Pluto was demoted to a dwarf planet, but research might indicate that there ...

Astronomers have uncovered a massive new trans-Neptunian object, 2017 OF201, lurking at the edge of our solar system. With an ...

WHETHER or not you believe in life beyond Earth, there are actually a minimum of 100 billion planets in our universe, according to a Nasa study. But how many planets make up our solar system?

A quick guide to planets, including the eight in our solar system, how they form, and how many could be in the universe.

Are there any planets outside of our solar system? – Eli W., age 8, Baton Rouge, Louisiana This is a question that human beings have wondered about for thousands of years.

From the scorching surface of Mercury to the icy edges of Neptune, our planetary neighborhood is full of wonders. The order of the planets isn’t just trivia—it tells a story about temperature, ...

This star, known as HD 110067, may have even more planets. The six found so far are roughly two to three times the size of Earth, but with densities closer to the gas giants in our own solar system.

Seeing the Solar System all in one night is a real eye-opener, but some of the planets aren’t easy to find. However, at least five of them are fairly straightforward, and that’s not a bad haul.

All solar system planets circle our sun with slightly tilted orbits — and a new study shows even distant planetary systems in quiet neighborhoods have orbital tilts, too.

It instead orbits in the star’s flat plane, like planets in our solar system, and perpendicular to HD 3167 c and d. This star system is the first one known to act like this.

Is there life on planets other than Earth? For generations, scientists have puzzled over the question, searching for planets that might have the right conditions both inside and outside the Milky ...