From faraway planets to the deepest depths of the ocean, 2012 has been an exciting year for scientific achievements and milestones.

Humans broke previously unimaginable barriers by detecting an elusive tiny particle and free-falling 24 miles from the edge of space. At the same time, we said goodbye to four retired NASA space shuttles that found new museum-type homes.

Here's our list of the biggest science achievements this year, in order of significance:

1. Curiosity lands, performs science on Mars

Every time I hear the word "curiosity" in a sentence, I'm tempted to butt in and ask if you're talking about the Mars rover Curiosity. She's really there! On Mars! Right now! And people are driving it! (Forgive me, I get excited about this.)

Landing this 2-ton rover flawlessly on the surface of Mars is our choice for the most exciting science moment of 2012. You can see from NASA's "seven minutes of terror" video how crazy-complicated that was -- the landing process included a supersonic parachute and a sky crane.

I'll never forget watching the live NASA feed with hundreds of other science enthusiasts at Georgia Institute of Technology in the first hours of August 6. James Wray, assistant professor at Georgia Tech, who is affiliated with Curiosity's science team, was next to me, rubbing his hands together in anticipation. And when the landing was confirmed, the room erupted in cheers and shouts. This was only one of many gatherings around the world celebrating this achievement.

And then there's all the stuff Curiosity's been doing since then, such as taking gorgeous photos, finding shiny objects, and coming across evidence that water once flowed on Mars.

We can't wait to see what Curiosity will do in 2013.

2. Higgs boson -- it's real

One of the most highly anticipated discoveries in all of physics happened this year -- well, probably. Scientists at CERN, the European Organization for Nuclear Research, said they used the Large Hadron Collider to detect a particle whose characteristics matched those of the Higgs boson.

What is the Higgs boson, you ask? It's basically a component of an invisible field, called the Higgs field, that is responsible for the mass of all the matter in the universe. In essence, it is why we are here.

Finding this particle, sometimes referred to as the "God particle" in popular culture, will fill a large gap in scientists' understanding about how the universe works. But it's not "God" in the way that you might think. Nobel Prize-winning physicist Leon Lederman wrote a book with "God Particle" in the title, but reportedly said he'd actually wanted to call it the "Goddamn Particle."

But wait, what about its mass? The two most precise ways that the particle has been measured have yielded slightly different values for its mass, said Beate Heinemann, scientist with the ATLAS experiment at the Large Hadron Collider. But these measurements are consistent, and with more data that difference should get smaller. "It all points at the moment to that this is indeed the Higgs boson," she said in an e-mail.

More results are expected in March 2013, she said.

3. James Cameron's deep dive

He didn't find The Heart of the Ocean necklace, but director James Cameron did probe the remotest depths of the ocean this year. In fact, using his one-man submersible, the maker of "Titanic" and "Avatar" traveled to the deepest known point in the world's oceans.

Cameron is the first to go alone to Challenger Deep, the name for that part of the Mariana Trench in the western Pacific Ocean. Here's a mind-boggling fact: Mariana Trench is deeper than Mount Everest is tall. Only two other humans have ever visited it.

In this cold, dark place, miles beneath the ocean's surface, Cameron said he did not see any fish, but did spot some "shrimplike animals." It took him 2 hours, 36 minutes, to get down there.

"It's a completely alien world," Cameron said.

4. Felix Baumgartner's record-breaking jump

Austrian daredevil Felix Baumgartner broke the speed of sound in October by jumping from the edge of space. He got up there on a balloon, then stepped off a platform 24 miles high and landed soon after in the New Mexico desert.

Baumgartner wore a 100-pound pressurized flight suit and helmet. Without protection, his blood would have been vaporized because the atmosphere was so thin when he jumped. The temperature at his launch point was estimated at 70 degrees below zero Fahrenheit, if not lower.

In doing so, Baumgartner broke the record for highest jump that had been set in 1960 by Col. Joe Kittinger. As part of a U.S. Air Force mission, Kittinger fell from 102,800 feet. He was a consultant for Baumgartner's efforts.

5. Planet with four suns