From landing on a comet to expanding our genetic alphabet, 2014 was an amazing year for scientific discoveries—just check out our Breakthrough of the Year section and our top 10 science news stories of the year. That means we got to see a lot of incredibly cool stuff over the past 12 months. Here are some of our favorite pictures from this year.

1. The Rosetta mission lands on a comet

The Rosetta mission and its landing of the Philae probe on comet 67P/Churyumov-Gerasimenko was one of the biggest science success stories of 2014—and our Breakthrough of the Year. This image of the comet’s surface, taken by Philae when it was just moments away from landing, is one of the mission’s most iconic.

2. The origin of the penis

It’s not a question a lot of scientists ponder out loud, but it’s key to much of life on Earth: Where does the penis come from? This image of a snake embryo shows tiny buds where legs would be if snakes had legs—but in fact, they’re actually the beginning of the snake's paired penises. After studying how the organ gets its start in snakes, lizards, mice, and chickens, researchers said they’ve finally figured out where the penis comes from.

3. The Z machine

In October, researchers using the awesomely named Z machine at Sandia National Laboratories in New Mexico reported a significant advance in the race toward nuclear fusion. They’ve detected significant numbers of neutrons—byproducts of fusion reactions—coming from the experiment. This not only demonstrates the viability of their approach, but also brings them closer to their ultimate goal of producing more energy than the fusion device takes in.

4. Two giant blue stars melding in space

Astronomers found further evidence of how phenomenally cool space is—and how little we know about it—when they discovered that the brightest object in a nearby star cluster isn’t a single star, but actually two massive blue stars in the process of merging (artist’s conception below). We don't know what will happen when the merging is complete: Some models predict the explosive release of a massive amount of energy, but others hint at a less violent outcome.

5. Adrift on an Arctic ice floe

Home alone for the holidays? It could be worse. Somewhere in the Arctic Ocean, two Norwegian scientists are adrift on an ice floe, equipped with a year’s worth of food and fuel—and one research hovercraft named SABVABAA (pictured). Right now, they’re drifting northward along the submarine Lomonosov Ridge, taking sediment cores to learn about the polar environment more than 60 million years ago.

6. An octopus supermom

This octopus died in 2011, but scientists didn’t tell her amazing story until this year. She was spotted in the same place, holding her eggs in her arms, for a whopping 4.5 years—smashing the previous record for egg brooding. In 53 months, she was never seen eating, and over time she turned from pale purple to ghostly white. Like most female octopuses, she died after her watch ended—but her eggs hatched successfully.

7. Rocks made out of plastic

In June, researchers reported finding a new type of rock made out of plastic on the shores of Hawaii. Called a plastiglomerate, the rock is cobbled together from plastic and organic matter like sand and coral. The discovery suggests humanity’s heavy hand in natural processes may be changing the world more than we realize.

8. An uncontacted tribe makes contact

This year, members of a previously isolated Amazonian tribe took a momentous step and made contact with the outside world. In this picture, a young man from the tribe clutches a bundle of used clothing, which some worry could have been a source of disease transmission, during initial contact with local villagers in July. Officials suspect that the tribe fled illegal logging and drug trafficking in their traditional homelands in Peru.

9. Spinosaurus, the swimming dinosaur

Meet Spinosaurus, the world’s biggest carnivorous dinosaur—and the only swimmer (as seen in this artist’s conception). In September, analysis of 97-million-year-old fossils revealed that 15-meter-long Spinosaurus is not only the largest land carnivore ever to exist, but it’s also the only dinosaur known to have made its home in the water.

10. Comet dust found on Earth

This is a single particle of comet dust, found preserved in the ice and snow of Antarctica—the first time it's ever been found on Earth’s surface. Comet dust is the oldest astronomical particle we can study and provides clues about how our solar system first formed, so scientists are excited to get their hands on this potential new source.