1. New Horizons nails the most distant flyby in history
Just 33 minutes after ringing in the New Year, scientists at the Johns Hopkins University Applied Physics Laboratory cheered and threw confetti a second time. The New Horizons spacecraft had just conducted a flyby of a Kuiper Belt object 4 billion miles from Earth. And as the sun rose on January 1, New Horizons beamed back its first close-up images of the 19-mile-long peanut-shaped space rock, officially named 2014 MU69.
Images eventually revealed 2014 MU69 (initially nicknamed “Ultima Thule”), to be a surprisingly flat “contact binary,” a body composed of two once-separated rocks that slowly gravitated toward each other until they lightly touched and fused. Scientists believe the flyby data could offer insight into how planets formed in our solar system billions of years ago.
In November, NASA changed the rock’s nickname from Ultima Thule, a term with links to the Nazi party, to “Arrokoth,” which means “sky” in the Powhatan/Algonquian language.
2. A second HIV patient enters long-term remission
Twelve years after a first patient was declared to be rid of HIV, another person achieved a similar milestone this year. In March, with the help of a stem cell transplant from a virus-resistant donor, the anonymous individual entered long-term remission from HIV.
In both cases, remission followed a transplant of bone marrow from a person with a mutation in the gene that encodes the protein CCR5, which many HIV strains use to infiltrate cells. Neither treatment was originally intended to eliminate the infection itself, but to treat blood cancers that had spread in both individuals.
While the intervention is likely to be effective in only a small fraction of HIV-positive individuals, the 2019 case shows that its efficacy was more than a one-time event.
3. Scientists reveal the first-ever black hole image
In April, we were able to feast our eyes on the first-ever image of a black hole. The black hole, whose image was generated from data captured by a network of eight radio observatories that make up the Event Horizon Telescope, dwells in the center of a galaxy some 55 million light-years away from Earth.
As popular as the black hole image was, another aspect of the story that quickly unfolded online: the contribution of 29-year-old MIT scientist Katie Bouman, who crafted an algorithm to help translate the telescope data into the black hole image. Bouman, captured in a photo with a laptop, beaming behind her folded hands, quickly became a symbol for women’s accomplishment in astronomy and computer science. But, Marina Koren writes for The Atlantic, “This one image tapped into a multitude of questions about the role of women in science, the myth of the lone genius, and the pressure scientists have to promote themselves and their work on social media.”
“No one algorithm or person made this image,” Bouman later wrote, referring to the black hole picture, in a Facebook post. “It required the amazing talent of a team of scientists from around the globe and years of hard work to develop the instrument, data processing, imaging methods, and analysis techniques that were necessary to pull off this seemingly impossible feat.”
4. First CRISPR clinical trials in the U.S. take place
In April, researchers began the first CRISPR-Cas9 gene-editing clinical trials in people in the United States. In the trials, scientists used CRISPR, a powerful gene-editing technique derived from an ancient bacterial immune system, to combat cancer and blood disorders. That month, two cancer patients—one with myeloma and one with sarcoma—were treated using CRISPR.
In the cancer and blood disorder trials, researchers remove some cells from a patient’s body, edit the cells’ DNA using CRISPR, and inject the cells back in, “now hopefully armed to fight disease,” Tina Hesman Saey writes for Science News. But in another trial, conducted by Editas Medicine in Cambridge, Mass., researchers are using CRISPR to edit DNA directly in the human body by “snipping a small piece of DNA out of cells in the eyes of people with an inherited form of blindness,” Saey writes.
The trials come on the heels of Chinese scientist He Jiankui’s gene-editing on twin girls born in November 2018, which was widely criticized as premature and highly unethical. .
5. New fossils capture the day the dinosaurs died—and the million years after
This year, scientists gleaned new insight into the day the dinosaur-killing asteroid crashed into Earth 66 million years ago, and the first million years after the impact.
In April, paleontologist and graduate student Robert DePalma claimed to unveil an unprecedented time capsule of the asteroid-induced catastrophe. He reported finding scorched tree trunks and hundreds of well-preserved fossil fish beneath sediment at a site in North Dakota, forming a snapshot of the first minutes and hours after impact. (Some experts remain cautious about the finding, due in part to the fact that DePalma’s discovery was first announced in a New Yorker article before publication of the peer-reviewed paper.)
Then, in October, new fossils that capture the million-year timeline of life after the dinosaurs died were revealed. Discovered in Colorado’s Corral Bluffs by paleontologist Tyler Lyson and his team, the fossils showcase the extraordinary resilience of life in the wake of disaster and help reveal the evolutionary journey of the mammals that survived the asteroid.
6. Racism persists in medicine and science
With the use of artificial intelligence on the rise, one serious flaw continued to make headlines in 2019: racial bias. In October, researchers announced that a particular algorithm, which predicts who might benefit from follow-up care and affects 100 million Americans, underestimates black patients’ need for additional treatment. The algorithm underestimates the health needs of black patients even when they’re sicker than their white counterparts.
Additionally, the U.S. remains one of the most dangerous developed nations in which to be pregnant and give birth, particularly for minorities. “Pregnancy-related deaths are rising in the United States and the main risk factor is being black,” Mike Stobbe and Marilynn Marchione write for AP News. A CDC report concludes “black women, along with Native Americans and Alaska natives, are three times more likely to die before, during or after having a baby, and more than half of these deaths are preventable,” Stobbe and Marchione write.
Also this year, researchers further investigated why black scientists are less likely to receive funding from the National Institutes of Health (NIH) than their white counterparts. A study published in October illustrated that topic choice contributes to the lower rates of NIH awards going to black scientists. “Specifically,” Jeffrey Mervis writes for Science Magazine, “black applicants are more likely to propose approaches, such as community interventions, and topics, such as health disparities, adolescent health, and fertility, that receive less competitive scores from reviewers.”
7. A new link is drawn between humans and Denisovans
New findings in 2019 added to anthropologists’ understanding of Denisovans, a species of early human that likely shared the planet with Homo sapiens as recently as 50,000 years ago.
This fall, scientists learned that although Denisovans’ DNA ties them more closely to Neanderthals, their fingers may have looked more like ours, suggesting Neanderthals’ broader digits evolved after their lineage split off from the Denisovans around 410,000 years ago. “A few more fossils,” Bruce Bower writes for Science News, “plus genetic analyses indicated Denisovans were close relatives and occasional mating partners of Neanderthals and Homo sapiens tens of thousands of years ago. But there was too little evidence to say what Denisovans looked like or how they behaved.”
8. Google claims quantum supremacy
Physicists reached a milestone in quantum computing this year, a method of computing that uses quantum physics to solve complex problems quickly.
In October, Google said it had achieved “quantum supremacy.” Its AI Quantum Team presented evidence that it had built a quantum computer that needs only 200 seconds to solve a problem that would have taken IBM’s Summit, the world’s most powerful supercomputer, 10,000 years to crack. Though IBM disputed the claim, others in the computing community are tentatively optimistic about the breakthrough’s promise. If validated, it may bring us closer to a future of ultra-efficient computing.
9. Saturn now has the most moons in the solar system
On October 7, the International Astronomical Union’s Minor Planet Center announced that researchers discovered an additional 20 moons orbiting Saturn, bringing its grand total to a whopping 82. Jupiter, the largest and oldest planet in our solar system, has 79.
The latest discoveries were made possible by Hawaii’s Subaru telescope. A team led by Carnegie Science’s Scott S. Sheppard first eyed them in the spring of 2017, but because faraway moons are dim and tough to spot, researchers used Subaru to scan the skies periodically throughout the following years to confirm their finding. Then, they used a computer algorithm to link the data through time and confirm that the moons were indeed reliably orbiting Saturn.
10. Climate change intensifies, and youth fight back
Less than a week after the U.N. climate talks came to a close in Madrid this month, Australia recorded its hottest day ever, one day after its previous record. Just a few months ago, wildfires raged across not only the American West and Australian Outback but also Europe and the Amazon, an occurrence that many climatologists believe may have been exacerbated by climate change-induced drought and high temperatures. And in May, a United Nations report claimed that one million plant and animal species are on the verge of extinction—more than in any other period in human history—with alarming implications for human survival. The warming climate, which heightens the effects of overfishing, pesticide use, pollution, and urban expansion is a major driver, the report concludes.
Three weeks ago, a “bleak” climate report, also from the U.N., predicted that global carbon emissions will climb “despite promises from almost 200 nations to address climate change, propelling temperatures upward and threatening to shatter the threshold of 2°C that scientists say would invite dramatic changes to ecology and the economy,” Nathaniel Gronewald writes for Science Magazine. And many declared this month’s COP25 climate talks to be a massive failure.
But climate activists, particularly teens, have seized the spotlight this year. Greta Thunberg, a 16-year-old Swedish climate activist, was just named TIME’s Person of the Year. And at COP25, official youth constituency representatives expressed their disappointment to leaders and officials, Kartik Chandramouli writes for Mongabay. “Do you want to be remembered as the ones who had the chance to act but decided not to as betrayers of our generation, of indigenous people and communities desperately fighting on the ground?” Youth representatives said. “We are rising, we are fighting and we will win.”