When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky A cloud of collapsing gas created our Sun, the first thing to form in ...

About 4.6 billion years ago, a celestial cloud collapsed, paving the way for our solar system to form. Then, a nebula with strong gravitational pull took shape, kick-starting the birth of the sun. But ...

Still, science being science, we needed proof—and we got it in 1992, when two astronomers found two planets orbiting a pulsar ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

There are 8 planets in our solar system. The planets orbit the Sun in elliptical trajectories, and they are all different in size, composition, temperature, and characteristics. The planets can be ...

Ian Whittaker does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond ...