This year, our list of most popular stories was dominated by 2012's most famous robot, a long-sought subatomic particle, 10 billion exoplanets and an amazing new spider species.
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Watch Live: Last Transit of Venus of Your Lifetime
On June 5, a rare celestial event captivated our readers. Venus crossed across the face of the sun for the second and last time this century. We ran several live feeds of the event in our most popular post of the year. The next transit of Venus is not expected until 2117. If you missed this year's event, we have some great video and photos of the event.