Scientists discovered a new type of aurora earlier this year. They named it STEVE, an acronym for Strong Thermal Emission Velocity Enhancement.
STEVE does not share the green and blue hues of other auroras. Instead, it looks purple and is surrounded by a green structure resembling a fence.
This aurora appears much closer to the equator than the northern lights, or aurora borealis.
Amateur sky-watchers first observed the strange lights in Southern Canada three years ago. They later collaborated with NASA, and the group's findings were published in March.
Each year, the UK's Engineering and Physical Sciences Research Council puts on a science photography competition. This year's winner was a stunning photo of a single positively charged atom of strontium.
The photo shows a glow of light emitted by an atom that's trapped by magnetic fields and laser light. It was taken by David Nadlinger from the University of Oxford.
While you can't see anything atomic-sized without incredibly advanced imaging techniques, digital cameras can capture the photons (or particles of light) that are absorbed and re-emitted by atoms.
Photographers also documented devastating natural disasters throughout 2018. In the fall, astronauts in space managed to take pictures of the fearsome hurricanes that battered the US East Coast.
Alexander Gerst, a German astronaut who returned to Earth in December, saw this stunning view of Hurricane Florence from the space station's windows in September.
"Watch out, America!" Gerst said in a tweet featuring the pictures he took.
The 2018 Atlantic hurricane season was above-average in terms of damage, causing more than $33 billion in losses, due in part to torrential rainfall. Florence was one of two major (Category 4 or above) storms that made landfall in the US; the other was Hurricane Michael.
Hawaii's Kilauea volcano sent ash clouds 30,000 feet into the sky when it erupted in May.
The lava flows severely damaged residential neighborhoods and forced more than 2,000 people to evacuate their homes.
High levels of sulfur dioxide in the air were a threat to children, elderly people, and those with respiratory problems, according to the US Geological Survey.
The Camp Fire destroyed almost the entire 27,000-person town of Paradise, California, in early November. Eighty-five people lost their lives.
It was the deadliest and most destructive wildfire in the state's history, scorching at least 150,000 acres.
This year, more than 7,900 fires burned across California, fueled by hot, dry conditions and aggressive winds. The fires could also be seen from space.
As the Woolsey Fire engulfed Malibu, California in November, Los Angeles Times photographer Wally Skalij took an eerie photo of an owl on the city's beach.
The Woolsey Fire killed three people and burned nearly 100,000 acres of land.
Skalij's photo of the owl has been shared widely on social media over the past month, but the photographer told NPR that he did not expect it to become so popular.
"My mind is racing 100 miles an hour because this house is burning up in the hills, and I know I have to get pictures of the firefighters battling that," Skalij said about taking photos on the Malibu beach during the wildfire. "I'm glad I pulled back a little bit to get a little more sense of what was going on away from the flames."
At least 1,700 people were killed in September following a deadly earthquake and tsunami in Indonesia. The woman pictured below lost her three children and home due to the disaster.
The earthquake and subsequent tsunami displaced thousands of people.
Indonesia's early detection warning systems were not working before the tsunami hit. The country's geophysics agency issued a tsunami warning during the natural disaster, but lifted the warning shortly after.
Medical firsts also made for unforgettable images this year. In January, 18 months after a suicide attempt, a 26-year-old man traveled from California to New York for a face transplant surgery.
Cameron Underwood survived a severe gunshot wound to his face. According to New York University's Langone Health center, the wound left him missing most of his lower jaw, his nose, and nearly all of his teeth.
Underwood's case was also notable because it marked the shortest period of time between a patient's injury and the transplant procedure.
A photo published in the New England Journal of Medicine earlier this month shows a bronchial tree-shaped blood clot that came out of a patient's mouth in an "extreme" coughing fit. The 36-year-old man passed away soon after.
The man had been admitted to the intensive care unit due a sudden worsening of chronic heart failure symptoms. Doctors had put the patient on blood thinners after he received a mechanical heart pump, but the medication was ineffective at stopping the clot from forming.
According to the New England Journal of Medicine, the coughing incident was not the cause of the 36-year-old's death.
Nikon's annual Small World microscope photography competition brought incredible images of an unseen universe to the public, including this shot of an Asian red palm weevil's eye flecked with green scales.
The first-place photo for the 2018 Nikon Small World contest shows the compound eye of a half-inch-long Asian red palm weevil, a type of beetle.
"Not all people appreciate small species, particularly insects," Yousef Al Habshi, the winning photographer, said in a press release. "Through photomicrography we can find a whole new, beautiful world which hasn't been seen before. It's like discovering what lies under the ocean's surface."
This photo also won a prestigious prize. It shows thousands of recalled Volkswagen and Audi vehicles sitting in the Mojave Desert, years after it was revealed that the car manufacturer was cheating on emissions tests.
Shot by Jassen Todorov in Southern California, the image won the grand prize in the 2018 National Geographic Photo Contest. It's titled "Unreal."
"Models manufactured from 2009 to 2015 were designed to cheat emissions tests mandated by the US Environmental Protection Agency," Todorov said. "Following the scandal, Volkswagen recalled millions of cars. By capturing scenes like this one, I hope we will all become more conscious of and more caring toward our beautiful planet."
The top prize in National Geographic's 2018 Travel Photographer of the Year contest went to this underwater view of a humpback whale calf's scuffed-up tail.
Photographer Reiko Takahashi calls the picture "Mermaid." He captured the image while snorkeling near Japan's Kumejima Island.
"Most of the time, the calf stayed close to her mom. At one point, the calf began jumping and tapping its tail on the water near us — it was very friendly and curious," Takahashi said. "Finally, the mother, who was watching nearby, came to pick up the calf and swim away. I fell in love completely with the calf and its very energetic, large, and beautiful tail."
Other memorable images from 2018 captured the year's biggest science news. In the US' midterm elections in November, Americans voted 10 new scientists and engineers into Congress (one senator and nine House reps).
The Democratic candidates who won all received support from 314 Action, a nonprofit political action committee focused on recruiting, training, and funding scientists and healthcare workers who are interested in running for office.
Kim Schrier, a pediatrician from Washington (shown here), was elected to represent Washington's 8th district in the House of Representatives.
The successful arrival of NASA's InSight lander on Mars was a major success for the agency. InSight took its first selfie on the red planet in early December, showing off its solar panels and scientific instruments.
InSight's selfie is made up of 11 images that were stitched together.
NASA's $830 million InSight mission to Mars is the first since the Curiosity rover reached the red planet more than six years ago. The lander touched down on Mars in late November, and scientists now plan to use InSight's tools to study Mars' internal structure and the history of its formation.
Other remarkable images from space came after the debut of SpaceX's Falcon Heavy rocket. Tech mogul Elon Musk demonstrated the system's power in February by blasting his own Tesla Roadster into space with a spacesuit-clad dummy called "Starman."
Several cameras on the Roadster led to images that were arguably more incredible than any taken of Falcon Heavy itself (which is currently the world's most powerful rocket).
The footage gave unprecedented views of the car and Starman against the backdrop of Earth and the inky black void of space. The visuals seemed unbelievable at times, but astronomers verified that the car was indeed up there.
SpaceX rocketed the sports car toward the orbit of Mars, to the annoyance of NASA's planetary protection office.
This time-lapse image of a SpaceX rocket launch is also remarkable, since it shows the company's as-yet unmatched capability of recovering orbital rocket boosters.
In 2018, SpaceX broke its own personal rocket-launch record (and that of the commercial space industry). The company's workhorse rocket, the Falcon 9, was behind that feat.
This photo shows a Falcon 9 rocket launching the SAOCOM-1 satellite into space from Vandenberg Air Force Base on October 8, 2018.
What's remarkable is that the time-lapse picture captured all stages of the launch.
The bright streak on the bottom right in the photo is from the blast-off, while the cloud at the top is the moment the rocket's upper-stage separated from the booster. Then the thin blue arc of exhaust is the 16-story-tall booster flying back, and the booster's landing burn is the shorter streak to the right of the central launch arc.
This image shows a less recent event: a "hybrid" solar eclipse on November 3, 2013. The picture is actually is a series of five photos stacked together; the collage was submitted to the Royal Society's 2018 photography contest — and it won.
The award-winning picture is titled "Three Diamonds in the Sky" and was shot by photographer Petr Horálek from Pakwero, Uganda.
This eclipse Horálek captured was a hybrid — not total eclipse or annular eclipse — due to where he was standing on Earth.
Some points on our round world are physically closer to the moon, and at those closer points, the moon's umbra or central shadow drops perfectly on Earth's surface. At more distant locations, however, the physics of refraction cause the moon's shadow to flip. This leads to leading to unusual lighting effects at those spots on our planet.
The next hybrid solar eclipse will occur in April 2023 over western Australia and Indonesia, Horálek said in a press release.
NASA's Juno spacecraft took this incredible series of Jupiter images on April 1, 2018. A few months later, NASA decided to extend the $1 billion mission.
Juno's views of Jupiter are as unprecedented as they are beautiful. The probe has been circling Jupiter since July 2016, completing a highly elliptical orbit called a perijove every 53.5 days. This path keeps the spacecraft from hanging out in the planet's dangerous radiation fields for too long.
At the pinnacle of the long loop, Juno speeds close to Jupiter's north pole going 130,000 mph, then moves along its surface and over the south pole. These flybys have led to numerous scientific revelations.
This series of images shows the last half of Juno's 12th perijove, and it includes views of Jupiter's south pole and Great Red Spot.
The Insight Astronomy Photographer of the Year honors those who look up, and this picture — which could easily pass for a sci-fi view from an alien planet — won the contest in 2018.
The stunning time-lapse image, titled "Transport the Soul," netted photographer Brad Goldpoint nearly $13,000 in prize money.
The photo shows the Milky Way galaxy (right), moon (center), and the tripod-wielding astrophotographer himself (left) perched on the lip of a desert canyon in Moab, Utah.
Other scenes from 2018 look alien in different ways, and contain dark truths. This award-winning shot shows Iran's evaporating Urmia Lake. Drought, damming, and irrigation have decimated the ecosystem by creating water eight times saltier than seawater.
Saeed Mohammadzadeh won the 2018 Environmental Photographer of the Year competition held by the Chartered Institution of Water and Environmental Management. His picture reveals how human activity can inadvertently destroy treasured local resources.
"Climate change is intensifying the droughts that speed up evaporation in the region. The lake has also been suffering from illegal wells and a proliferation of dams and irrigation projects causing it to reduce significantly in volume," Mohammadzadeh said in a release. "Noxious, salt-tinged dust storms inflame the eyes, skin, and lungs of residents in surrounding areas."
Many of Earth's creatures are threatened by human activity, including elephants. This image earned a certificate of merit in the 2018 Sanctuary Wildlife Photography Awards.
The annual contest highlights beautiful and often gut-wrenching wildlife shots, many of which reveal the human-created dangers that animals face.
Called "Impossible Odds," this photo by Biplap Hazra shows an adult elephant and a calf trying to cross railway tracks in West Bengal. The picture is part of an ongoing series in which Hazra documents threats to elephants' way of life.
"Here in the Bankura district, beleaguered herds desperately navigate a landscape that would be unrecognizable to their fore-mothers," the contest's organizers wrote about the photo. "The railway authorities didn’t consider their ancient pathways when they laid this track, and every year a memory’s worth of elephants is wiped out by speeding trains."
Not all great nature photos need to be serious or solemn, though. Photographing wildlife often leads to humorous situations — a fact that the Comedy Wildlife Photography Awards bank on.
This image, titled "Wildlife PhotograBear" and captured by Roie Galitz, shows a polar bear inspecting his strange-smelling and unusual-looking camera setup on Norway's Svalbard Island.
Galitz's shot was a highly commended image in the 2018 Comedy Wildlife Photo Awards, though it was just one of many hilarious pictures in the contest.
