Science mattered more than ever in 2013. Climate science questions raged after Super Typhoon Haiyan pummeled the Philippines. And scientific expertise figured in disarmament debates in Syria and in Iran's proposed halt to its nuclear activities.

Meanwhile, on the pure research front, investigators made plenty of intriguing discoveries in 2013. With plenty to choose from, and argue over, here's a top five list of some favorites from the year. And while you're at it, check out National Geographic's Year in Review.

Of course, not all of them are places you would want to live. A November analysis from NASA's Keck Observatory team suggested that one in five stars may have Earth-size planets orbiting in their "habitable zones"—zones