" " Image courtesy NASA/JPL-Caltech In 2013, we learned our beloved Milky Way may host billions of stars with Earth-like planets.

In November 2013, astronomers made a startling announcement: The Milky Way galaxy hosts at least 8.8 billion stars with planets the size of Earth. Those planets, the researchers said after studying NASA's Kepler data, revolve around their suns in a so-called Goldilocks zone. That zone is where life, as we know it, can exist.

"Just in our Milky Way galaxy alone, that's 8.8 billion throws of the biological dice," said Geoff Marcy, one of the study's authors [source: Borenstein].

The Kepler telescope, which experienced technical problems in summer 2013, was gazing at a thin slice of the Milky Way to see how many Earth-like planets might be out there. The astronomers then did some math homework and extrapolated that figure to the rest of the galaxy. The next step is to see if these Earth-like planets have atmospheres. The right kind of atmosphere is a good indication that life might exist on the planet's surface [source: Borenstein].

That finding is just one of many scientific discoveries that made headlines in 2013. Wait until you hear the other 10.