The year 2014 was a packed one for astronomical science.

Over the last 12 months, scientists made historic progress in the study of Mars, had two close encounters with comets, and may have found hints of dark matter and signals from the Big Bang. It's enough to make us eager for 2015 to see what new discoveries await.

But there are some stories that stand out from the crowd that was space science in 2014. Here is our list of the biggest astronomy stories of the year:

Tantalizing new information about the Red Planet, along with new clues about the possibility that it once supported life, was revealed this year. 2014 also happens to be the 50-year launch anniversary of the first probe ever sent to Mars.

In December, scientists working on the Mars rover Curiosity announced that the Red Planet hosts organic chemicals (those that contain carbon and are the building blocks of life on Earth). The chemicals chlorobenzene, dichloroethane, dichloropropane and dichlorobutane were discovered inside a rock that Curiosity drilled into in May 2013. Researchers stressed that their findings do not indicate that life exists or ever existed on Mars but it does open the door of possibility.

In addition, scientists confirmed in December that the rover had detected methane on Mars, despite not finding any trace of methane last year. Living organisms on Earth are known to produce high levels of methane, so its presence on the Red Planet is another possible sign of life.

NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft arrived at the Red Planet on Sept. 21, just in time to observe the flyby of Comet Siding Spring. The $671 million mission will focus on uncovering the events that changed the planet from a world with lakes and rivers, to a complete desert.

Just two days after MAVEN, India's Mars Orbiter Mission (MOM) arrived at the fourth planet from the sun. The $74 million mission is India's first probe to reach Mars. MOM is carrying a camera (and has already snapped some stunning photos), and four scientific instruments that will study the planet's surface and atmosphere.

The swarm of activity around Mars came during the 50-year anniversary of the launch of the Mariner 4 spacecraft in 1964. Mariner 4 was the first probe to ever fly by Mars and the first mission to take up-close images of another planet from deep space. In celebration of the anniversary, the space-funding company Uwingu used radio telescopes to beam nearly 90,000 messages straight at the Red Planet.

The BICEP2 collaboration grabbed headlines in March when it claimed to have found evidence that our universe rapidly expanded after the Big Bang, causing ripples in the fabric of the universe. By September, outside evaluation had thrown serious doubt on the findings.

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The Biggest Astronomy Stories of 2014