The International Astronomical Union defines a planet as a celestial body that orbits the sun, is massive enough that gravity has forced it into a spherical shape, and has cleared away other objects ...

You know what a planet is, right? A big round thing that orbits a star. Uh, not so fast. You know what a planet is, right? A big round thing that orbits a star. Uh, not so fast. The surprisingly ...

LOS ANGELES – Our solar system is suffering an identity crisis. For decades, it has consisted of nine planets, even as scientists debated whether Pluto really belonged. Then the recent discovery of an ...

When someone says the word embryo, what do you think of? Probably that picture you’ve seen a thousand times on a thousand different news articles: a translucent orb swelling with cytoplasm being ...