[The text below is a modified transcript of this video.]

2012 is almost over and it’s time take a look back at the top space stories of the past year. We’ll find out what happened in the weeks and months after the news broke. And, hey, don’t forget to tell us your top five in the comments.

5) Nearby Exoplanet

In October, an exoplanet was discovered in one of the closest star systems to the Earth. Orbiting around a star called Alpha Centauri B, the planet has a mass similar to Earth’s, but the proximity to its star makes the temperature too high to support life. This is the closest exoplanet we’ve discovered so far. So what’s stopping us from going there and exploring a new solar system?

Well, it’s the distance. This star system is four light years away from Earth. Space vehicles like the Voyager would take at least 400 centuries to get there. Scientists are currently researching ways to shorten the journey. While some suggest faster space vehicles, others are working on building spaceships that are more along the lines of time machines. They would cut through space, faster than the speed of light and bend space-time.

4) Water on Mercury

In late November, scientists discovered water on a planet beginning with the letter M--just not the one we were expecting. Data analyzed from the Messenger probe indicates the planet Mercury probably has water, in the form of ice, at its poles.

This may seem a little strange given that Mercury is the closest planet to the sun and its surface temperature can reach over 400 degrees Celsius. Apparently, the water hides out in large craters nears the planet’s poles. Mercury’s rotational axis is almost perfectly perpendicular to its orbit, so its poles stay in permanent shadow, with temperatures never reaching above -170 degrees Celsius. Scientists think the water arrived on the planet by hitching a ride on comets. It vaporized and condensed near the poles.

Launched in 2004, the Messenger spacecraft moved into orbit around Mercury in 2011. So far, it has orbited the planet 1000 times and produced over 100,000 images leading to numerous discoveries. As the data keeps pouring in we can probably expect more news on Mercury in 2013.

3) First Private Spacecraft Docks with ISS

This May, the privately owned company SpaceX made history when its Dragon capsule became the first commercially-manufactured spacecraft to dock with the ISS. In the past, it's taken government agencies to build vehicles with this capability.

With the end of NASA's space shuttle program, Dragon became responsible for resupplying the ISS. Although SpaceX signed a contract with NASA back in 2008, Dragon didn't make its first official run until October of this year. But the capsule's isn't limited to supply runs. Dragon can also act as a free-flying spacecraft and could someday carry humans: In August, SpaceX won funding from NASA to develop Dragon for human transport.

The Dragon capsule is only one of many successes for SpaceX. With NASA and US military contracts, and plans for a colony on Mars, this company will continue to expand the private sector's presence in space. The ascendency of SpaceX raises the question: Is the future of space travel in commercial hands? Let us know what you think in the comments below.

2) Curiosity on Mars

Private companies like SpaceX may be thriving, but NASA is hardly twiddling its thumbs. The agency pulled off a major success when the Mars Science Laboratory, better known as the Curiosity rover, touched down perfectly on August 5. While we celebrated from NASA to Times Square here on Earth, Curiosity got right to work, and boy has it been busy.

The rover has turned into quite the photographer, sending us beautiful Martian vistas, close-ups of rocks and soil, and even a self-portrait. More than an artist, Curiosity is also traveling across the planet's surface, drilling and zapping rocks with lasers, gathering information about the soil and atmosphere, and finding proof that water once flowed on Mars.

And Curiosity's success has inspired new plans for Mars exploration. Now, NASA wants to send another rover to the planet, and even to bring samples of Martian soil back to Earth. Stay tuned for 2020, when the new rover is scheduled to launch.

1) Higgs Discovery

In July , scientists announced the discovery of a particle matching the profile of the Higgs boson. The Higgs discovery showed the standard model of physics holds up and the universe works pretty much how scientists thought it did. Physicist Peter Higgs had predicted the existence of the Higgs boson in the 1960s, but scientists were only able to detect it by slamming particles together at insanely high speeds inside the Large Hadron Collider.

Since then, follow up experiments have shown the initial measurements were spot on and the particle has a mass of 125 to 126 times the mass of a proton--just as predicted*. The news made waves around the world and in a surprise move Time magazine even nominated Higgs, the particle not the scientist, as person of the year.

Unfortunately, it didn’t win and now a feeling universal sadness permeates the cosmos.

- Portions of the script above written by Sophie Bushwick, Eric R. Olson & Isha Soni

*Update: After filming this episode of The Countdown, new data was released that hints at multiple Higgs Bosons with masses of about 123.5 and 126.6 times the mass of a proton.