 2019 was a big year for science. Since everyone's been looking back at the year and what happened, we thought why not take a look back at some of the biggest scientific discoveries of 2019. Don't forget to subscribe and hit that notification bell so you don't miss out on any future uploads and let's jump in. We started the year off strong. On New Year's Day, NASA's nuclear-powered New Horizons spacecraft flew past a mysterious mountain-sized object some 4 billion miles from Earth. The object, which was renamed from Ultima Thule to Aracoth, is the most distant object humanity has ever visited. The New Horizons probe took hundreds of photographs as it flew by the space rock at more than 32,000 miles per hour, revealing it to be oddly flat for a celestial body. The flyby is helping to reveal new clues about the Solar System's evolution and how planets like Earth formed, though scientists haven't even finished receiving all the data yet. Just days after New Horizons flyby, China's chain 4 mission was the first to put a rover and lander on the far side of the moon, the part we can't see from Earth. Before chain 4's success, no country or space agency had ever touched the far side of the moon. The rover landed in the moon's south pole, which is the site of a cataclysmic collision that occurred around 3.9 billion years ago. The celestial smashup left a 1,500-mile-wide impact site that likely punched all the way through the moon's crust. By landing the spacecraft in this crater, scientists hoped to study some of the moon's most ancient rocks. Elsewhere in the Solar System, NASA scientists learned about the existence of Mars quakes, the red planet's version of Earthquakes. This discovery came from NASA's inside lander, which first touched down on Mars in November 2018 and has given scientists the unprecedented ability to detect and monitor these quakes. The lander's built-in seismometer detected its first Mars quake in April, and since then researchers have recorded more than 100 seismic events, about 21 of which were likely quakes. They hope that by studying these quakes, they'll learn more about what lies underneath the Martian surface. And over 5 million miles from Earth, the Japanese spacecraft Hayabuso-2 touched down on the surface of an asteroid. The probe was first launched way back in December of 2014, but didn't land on the asteroid's surface until this past year, after its long journey. What makes this mission special was it was the first to collect samples from another celestial body to bring back to Earth. By studying the asteroid's innermost rocks and debris, which have been sheltered from the wear and tear of space since the formation of the solar system, scientists hope to learn how asteroids like this may have seeded Earth with key ingredients for life billions of years ago. And even further out, scientists discovered a planet outside our solar system that could be our best bet for finding alien life. In September, scientists announced they detected water vapor on a potentially habitable planet for the first time. The planet, named K-218B, is a super-Earth that orbits a red dwarf star some 110 light years away. K-218B is the only known exoplanet or planet outside our solar system with water, an atmosphere, and a temperature range that could support liquid water on its surface. That makes it the best candidate for habitability out of any planet discovered today. This was also a huge year for the study of black holes. In April, the Event Horizon Telescope team published the first-ever image of a black hole. The unprecedented image that set the internet abuzz shows the super-massive black hole at the center of the Mesa87 galaxy, which is about 54 million light years away from Earth and weighs more than 6 billion times the mass of our Sun. Though the image is somewhat fuzzy, it showed that, as predicted, black holes look like dark spheres surrounding by a glowing ring of light. Since black holes are, well, black, and they distort space-time around them, scientists struggled for decades to capture one on camera. But while it snatched all the headlines, this wasn't the only black hole breakthrough this year. For the first time, scientists detected a black hole devouring a nearby neutron star. In August, astrophysicists detected the aftermath of a collision between a black hole and a neutron star. The super-dense remains after a star goes supernova at the end of its life. The catastrophic collision nearly a billion years ago created ripples in space-time known as gravitational waves, large enough for the ground-based LIGO system to detect. This was only the third event big enough for scientists to detect, since gravitational waves were first discovered in 2015, after they were predicted by Einstein 100 years prior. This year also saw many innovations in space travel technology. In March, SpaceX underwent the first launch of the Crew Dragon system, a commercial spacecraft designed to put NASA astronauts into orbit. The maiden flight of the Crew Dragon marked the first time that a commercial spaceship designed for humans left Earth. It was also the first time in eight years that an American spaceship made for people launched into orbit. Crew Dragon's successful test flight was a critical milestone for the US, since NASA retired its fleet of space shuttles in 2011. And back here on Earth, scientists have made monumental, though often troubling discoveries. Climate researchers found that the Antarctic and Greenland ice sheets are melting at unprecedented rates. In April, a study revealed that the Greenland ice sheet is losing on average 286 billion tons of ice per year. Two decades ago, the number was just 50 billion. Antarctica meanwhile lost an average of 252 billion tons of ice per year in the last decade. For comparison, in the 1980s, it was only 40 billion. And researchers' predictions about coming sea level rise are getting more accurate and scarier. Estimates suggest the world's oceans could rise three feet by 2100, which would affect hundreds of millions of people around the world. And another landmark UN report revealed that between 500,000 and a million plant and animal species face extinction, many within decades. The report, published in April, estimated that 40% of amphibian species, more than a third of all marine mammals and reforming corals, and at least 10% of insects are threatened, largely as a result of human actions. And they found that more than 500,000 land species already don't have enough natural habitat left to ensure their long-term survival. Although, on the bright side, one nearly long-lost species emerged from the wilderness this year. In June, scientists spotted a giant squid in its deep sea habitat off the Gulf of Mexico. The giant squid, which inspired the legend of the Kraken monster, has only ever been caught on video one other time, because they rarely leave the icy depths of their habitat more than 3000 feet below the water. And in rockier news, anthropologists dug deep into the earth to make incredible discoveries in 2019. In August, researchers announced they found the oldest skull ever seen from one of our human ancestors, the nearly intact skull, which belonged to the species Australopithecus enaminensis, is 3.8 million years old. The fossil, nicknamed MRD, revealed that these ancient people had protruding faces with prominent foreheads and cheekbones. MRD's age also suggested that these human ancestors coexisted with another species of human ancestor, Australopithecus afarensis, for at least 100,000 years. Researchers also discovered the fate of the last known group of Homo erectus, one of humanity's longest lived ancestors. Anthropologists revealed that a population of Homo erectus from the island of Java died between 117 and 108,000 years ago, and is the last known appearance of Homo erectus in the fossil record. The individuals seem to have perished in a mysterious mass death, after which the bones were swept downstream in a flood. Zooming in, physicists, engineers, and biologists made big breakthroughs this year too. This summer, researchers captured quantum entanglement on camera for the first time. According to quantum mechanics, two particles can be paired and separated. They remain intimately and instantly connected across vast distances. So one particle will affect the other, no matter how far apart they are. This is quantum entanglement, and the strange phenomenon rattled Albert Einstein so much that he died believing it couldn't exist. And in October, engineers at Google announced they had created a quantum computer that could perform a computation in just over three minutes that would take the world's fastest supercomputer 10,000 years to achieve. This achievement in quantum computing, a field of study that strives to enable computers to perform exponentially faster than today's machines, could be used to improve artificial intelligence or assist in the development of new drugs. Google described the milestone as quantum supremacy, meaning their computer did something a conventional computer could never do. In other news, researchers at the World Health Organization garnered a big win for the fight against Ebola in the Democratic Republic of the Congo. In July, the WHO declared the Ebola virus outbreak in Africa a global health emergency. But fortunately, two experimental treatments were found to dramatically boost survival rates. The two treatments were a cocktail of antibodies injected directly into the bloodstream that could save 90% of people infected with the Ebola virus. Well, that's it for our action-packed recap of 2019. With the turn of the century, we can only hope there are plenty more discoveries yet to come. If you liked the video, don't forget to subscribe and hit that notification bell so you never miss an upload. And remember, there is always more to learn.