About twenty years ago, no planet was known outside of our solar system. Researchers say this fall we've known the exoplanet 1000. Officially, Michel Mayor and Didier Queloz found the first exoplanet: 51 Peg b.

But still, the main way to capture planets is to observe them. In fact, if a star's brightness changes periodically, that means there's something between it and us. However, this method confuses the true planets with the “spots” of other types. Surely in the coming years we will know that many of those who have been considered planets are something else.

Without mistakes, we are sure that there will be more planets found than the ones deleted from the list. So we're getting closer and closer to finding a Earth-like planet.