Snow monkey spa
You can almost hear this Japanese macaque, or snow monkey, saying "aaah" as it melts into the man-made hot spring during a chilly winter day. This year, scientists learned why they like to bathe in these springs: They're cold. More specifically, lower the monkeys' levels of biological stress. "This indicates that, as in humans, the hot spring has a stress-reducing effect in snow monkeys," study lead author Rafaela Takeshita, of Kyoto University in Japan, said in a statement.
New brain cells
Your brain keeps making new nerve cells, even as you get older. And they're beautiful. The study, published in April, suggests that aging brains produce just as many new brain cells as young brains do, something that surprised scientists who looked at brains from corpses of individuals who died between ages 14 and 79. They sliced up each brain's hippocampus and counted the newly formed brain cells to come to their conclusion. However, there were differences between old and young brains: The older brains appeared to be making fewer new blood cells and they weren't forming new connections between brain cells as quickly. Shown here, developing nerve cells, with the nuclei shown in yellow.
Whale's rainbow sneeze
Would the world be a better place if we could all just sneeze rainbows? Well, maybe not, but this humpback whale image suggests goodness is hiding all over the planet. Fortunately, wildlife photographer Domenic Biagini was in the right place at the right time to capture footage of what looks to be a rainbow spraying from the whale's blowhole; Biagini then shared the image on Reddit in April. Being an oxygen-breathing mammal, a whale exhales a mixture of warm air, some water vapor and plenty of whale snot. In this whale's case, the water vapor caught the sunlight just perfectly — in the same way raindrops do when they refract light into its constituent colors, creating rainbows.
Jupiter's hellish storms
While Jupiter is infamous for its bigger-than-Earth storm that has raged near the planet's equator for centuries — and is so hellish it's called the Great Red Spot — another glowing, swirling system at the north pole mesmerized Earthlings this year. In April, NASA released a video showing a 3D flyover of the gas giant's north pole in infrared light. The views relied on data from NASA's Juno mission, revealing the turbulent 2,500-mile-wide (4,000 kilometers) cyclone at its top. That's not all, as the monster is ringed by eight other cyclones, each with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,700 km). The flyover is worth the 1 minute-plus it takes to watch.
Sun hole aurora
Dramatic auroras were the first sign on the night of April 10 that a stream of charged particles that had escaped from a hole in the sun's atmosphere had made its way through Earth's upper atmosphere. The glorious Northern lights appearing at latitudes as low as Williston, North Dakota. Here, the coronal hole on the sun seen in an image captured on April 10, by NASA's Solar Dynamics Observatory.
When gross is … stunningly cool-looking. Treetop-dwelling ants from Southeast Asia take down their foes by blowing themselves up, rupturing their cell walls and spattering toxic body fluids all over prey. And this year, scientists found such "exploding ants" (which sacrifice their own lives with the goo-spattering weapon) encompass not one, but 15, separate species, including one previously unknown species in Borneo, which they described in a new study released in April.
You can't help but think this Mary River turtle should have a guitar in its claws. As Live Science's Brandon Specktor described the punk rocker reptile in April: "With whisker-like growths forking out of its chin and shocks of algae bursting off of its head like a punky green mohawk, the freshwater swimmer looks as much like an aging rocker as it does an endangered species." The looker drew headlines in the spring when it took spot 29 on the Zoological Society of London's list of the world's 100 most endangered reptiles.
Yellowstone magma pit
This year, scientists announced they were closer than ever to understanding how Yellowstone became the powerhouse of supervolcanoes. Using a computer model, the team found that 7 million years of underground unrest led up to the creation of the dual magma chambers that animate the Yellowstone caldera in modern times. Shown here, the Grand Prismatic Spring, which is one of the many signs of this hidden supervolcano.
Is ugly the new cute? Probably not, but we chose this image as one of our top science photos of the year because, this fish is, well, a badass. This venomous, armored stonefish has not one but two "switchblades" embedded in its skull. And scientists only just discovered these onboard assassin weapons this year. Moral of this story: Don't invite the armored stonefish to your next holiday party.
These dinner plate-size octopuses, which sport relatively enormous eyes, were spotted in droves this year clinging to hardened lava from an undersea volcano. Scientists were amazed when they came upon hundreds of the octopuses in footage captured by a submersible on the Dorado Outcrop, located about 155 miles (250 kilometers) west of Costa Rica. Not only was this quite a crowd of cephalopods, but many of them were mothers protecting clusters of eggs.