- Astronomers, anthropologists, geologists, and many other scientists made mind-boggling breakthroughs in 2019.
- Some highlights include work that produced the first image of a black hole, traced the origins of modern humans, and predicted future sea-level rise.
- These are 26 of the biggest scientific accomplishments of the year.
In 2019, scientists around the world pulled off some impressive feats: They imaged a supermassive black hole for the first time, debuted two treatments for the Ebola virus, and launched a spacecraft into orbit that's powered by sunlight alone.
Over the past year, researchers have also discovered a hidden continent, captured video of a giant squid in its deep-sea habitat, and sent a probe to an asteroid 5.5 million miles from Earth.
These and other accomplishments are improving scientists' understanding of our own biology, our planet, and the surrounding cosmos.
As a new year — and a new decade — approaches, here's a look back at some of the most mind-boggling scientific discoveries from 2019.
On New Year's Day, NASA's nuclear-powered New Horizons spacecraft flew past a mysterious, mountain-sized object 4 billion miles from Earth.
The object, called MU69, is nicknamed Arrokoth, which means "sky" in the Powhatan/Algonquian language (it was previously nicknamed Ultima Thule). It's the most distant object humanity has ever visited.
The New Horizons probe took hundreds of photographs as it flew by the space rock at 32,200 miles per hour.
Images revealed that Arrokoth is flat like a pancake, rather than spherical in shape. The unprecedented data will likely reveal new clues about the solar system's evolution and how planets like Earth formed, though scientists are still receiving and processing the information from the distant probe.
Just days after New Horizons' fly-by, China's Chang'e-4 mission put a rover and lander on the far side of the moon — the part we can't see from Earth.
Before Chang'e-4's success, no country or space agency had ever touched the far side of the moon.
The name "Chang'e" is that of a mythical lunar goddess, and the "4" indicates that this is the fourth robotic mission in China's decade-long lunar exploration program.
The rover landed in the moon's South Pole-Aitken Basin, which is the site of a cataclysmic collision that occurred about 3.9 billion years ago. The celestial smash-up left a 1,550-mile-wide impact site that likely punched all the way through the moon's crust. Landing the spacecraft in this crater could therefore enable scientists to study some of the moon's most ancient rocks.
In order to collect samples from deep within the space rock, Hayabusa-2 blasted a hole in the asteroid before landing. The mission plan calls for it to bring those samples back to Earth. By studying Ryugu's innermost rocks and debris — which have been sheltered from the wear and tear of space — scientists hope to learn how asteroids like this may have seeded Earth with key ingredients for life billions of years ago.
The probe beamed back unprecedented data about previously unknown boundary layers at the far edge of our solar system — an area known as the heliopause.
The discovery of these boundary layers suggests there are stages in the transition from our solar bubble to interstellar space that scientists did not know about until now.
Though the image is somewhat fuzzy, it showed that, as predicted, black holes look like dark spheres surrounded by a glowing ring of light.
Scientists struggled for decades to capture a black hole on camera, since black holes distort space-time, ensuring that nothing can break free of their gravitational pull — even light. That's why the image shows a unique shadow in the form of a perfect circle at the center.
The catastrophic collision nearly a billion years ago created ripples in space-time, also known as gravitational waves. They passed through Earth this year.
This was the third event scientists observed using gravitational-wave detectors. In 2015, researchers detected waves from the collision of two black holes, and in 2017 they observed two neutron stars merging.
Einstein predicted the existence of gravitational waves in 1915, but thought they'd be too weak to ever pick up on Earth. New tools have proved otherwise.
As light particles reflect off that sail, they transfer momentum to the spacecraft.
A spacecraft that utilizes a solar sail in this way has an almost unlimited supply of energy. Advancing this type of propulsion technology could one day help spacecraft reach nearby star systems that aren't currently accessible due to the finite amount of fuel we can launch off the planet.
In April, a study revealed that the Greenland ice sheet is sloughing off an average of 286 billion tons of ice per year. Two decades ago, the annual average was just 50 billion.
In 2012, Greenland lost more than 400 billion tons of ice.
Antarctica, meanwhile, lost an average of 252 billion tons of ice per year in the last decade. In the 1980s, by comparison, Antarctica lost 40 billion tons of ice annually.
What's more, parts of Thwaites Glacier in western Antarctica are retreating by up to 2,625 feet per year, contributing to 4% of sea-level rise worldwide. A study published in July suggested that Thwaites' melting is a time bomb that is likely approaching an irreversible point after which the entire glacier could collapse into the ocean. If that happened, global sea levels would rise by more than 1.5 feet.
Another study suggested that the number of people displaced by sea-level rise could reach 630 million if greenhouse-gas emissions continue to rise through 2100.
In 2012, scientists from Japan's National Museum of Nature and Science filmed a giant squid in its natural habitat in the Ogasawara archipelago.
Hundreds of millions of years ago, Earth had one giant supercontinent named Pangea, which eventually broke up into our modern-day continents. A recent study showed that in that process, an eighth continent slid under what is now southern Europe about 120 million years ago.
It's still hidden deep within the Earth.
The researchers named this continent Greater Adria. Its uppermost regions formed mountain ranges across Europe, like the Alps.
The nearly-intact skull, which belonged to the species Australopithecus anamensis, is 3.8 million years old. The fossil, nicknamed "MRD," revealed that these ancient people had protruding faces with prominent foreheads and cheek bones, much like other Australopithecus species in the fossil record.
"The MRD find is an iconic cranium," paleoanthropologist Tim White told Nature.
MRD's age also suggested that these human ancestors coexisted with another species of human ancestor, Australopithecus afarensis, for at least 100,000 years. The nearly complete skeleton "Lucy" was a member of the latter group, which roamed Africa between 3.9 million and 3 million years ago.
