The Top 10 Science Stories of 2017

Scientific breakthroughs of 2017 truly spanned a gamut, manifesting themselves in nearly every discipline—cosmology, biology, and anthropology, to name a few. They ranged from astonishing revelations about Jupiter's famous rings to discovering a new continent on our own planet. Human cellular and embryonic sciences were in the limelight: Researchers fixed a disease-causing gene in human embryos in one experiment and grew human cells in pig embryos in another. Here on Earth, scientists achieved the first ever teleportation (of a particle). Far away, cosmic forces forged an enormous amount of gold, literally of galactic proportions—200 times the mass of our planet. Here are the top 10 most notable science stories of 2017.

1. WE FOUND SEVEN EARTH-LIKE PLANETS ORBITING A DIM STAR.

We found not one but seven Earth-like planets, out of which three could potentially host life. Orbiting around a cool, dim star 39 light-years from us in the Trappist-1 system, these planets were detected through their eclipses—a brief dimming in their star's brightness when a planet passes in front of it. Although Trappist-1 looks more like Jupiter and its Galilean moons than our own solar system, its seven Earth-sized planets may have "terrestrial" conditions. Three of the planets are located in the habitable zone with their surface temperatures allowing for water oceans and an Earth-like atmosphere to form.

So far, most planet-hunting efforts were focused on brighter stars and bigger planets. Trappist-1 is the first planetary system found to revolve around a smaller, dimmer star—and its discovery holds the potential to uncover many more exoplanets.

2. WE CUT A DISEASE-CAUSING MUTATION FROM HUMAN GENES.

Scientists have successfully used a gene-editing technique, CRISPR-Cas9, to clip out a mutated gene in human embryos, replacing it with a healthy copy. Called MYBPC3, the defective gene causes hypertrophic cardiomyopathy, a heart condition that can lead to sudden death in young people. While this was a stunning medical success, the CRISPR-Cas9 technique remains controversial among doctors, ethicists, and sociologists, who are concerned that attempts to build a better human could lead to dismal medical and social outcomes. When the study was published, an international committee of genetics experts issued a statement advising against editing any embryo intended for implantation into future mothers.

A different group of scientists managed to convert CRISPR into a fast, sensitive, and cheap diagnostic instrument for a range of diseases. Called SHERLOCK (for Specific High Sensitivity Enzymatic Reporter UnLOCKing), this method turns CRISPR into a tool that can sniff out specific genetic information, such as abnormal RNA. Surprisingly inexpensive, SHERLOCK can cost less than a buck per sample, and can hunt down the RNA of disease agents like dengue fever or Zika virus, and even search for mutations that can cause cancer.

3. THE LARSEN C ICE SHELF BROKE, BECOMING ONE OF THE LARGEST ICEBERGS EVER.

A giant piece of ice the size of Delaware broke off the Larsen ice shelf on the Antarctic Peninsula, and is now adrift in the Weddell Sea. Weighting a trillion tons, it's one of the largest icebergs ever recorded.

Over the last few decades, the Larsen ice shelf went through major changes. The sections called Larsen A and B collapsed in 1995 and 2002. More recently, a rift along the Larsen C section was detected, and it grew slowly over two years—until it was hanging by a thread, and then finally split off.

The scientists say that while climate change is responsible for melting sea ice around the world, this particular fracture may have been inevitable. Ice shelves naturally break up as they extend further out into the ocean. Neither will the massive iceberg cause a sea level rise as it melts—the same way ice cubes melting in your gin and tonic do not increase the volume of water in that glass.

4. WE ACHIEVED TELEPORTATION (OF PHOTONS, AT LEAST).

Purely the stuff of science fiction until now, teleportation became possible this year. Although not yet able to teleport an entire human, Chinese scientists said they managed to teleport a photon particle from the ground to a satellite 870 miles away.

How does it work? Teleportation is transmitting the state of a thing rather than the thing itself. It's not unlike a fax machine, which sends information as various marks on a paper sheet rather than the sheet itself.

If you combine this idea with the concept of quantum entanglement, in which two particles are created at the same time and place, so they effectively have the same existence, you can shoot one of the particles far away, but they will remain entangled—meaning if one changes, its remote twin will change too. So it's not a Star Trek–type of teleportation, where you can transfer objects or people from one place to another, but more like having a doppelganger tethered to you far away.

Instead of sending marks on a paper sheet to a receiving-end fax machine, the Chinese scientists transmitted a bunch of photons. The team created 4000 pairs of quantum-entangled photons and fired one photon from each pair in a beam of light towards a satellite that can detect the quantum states of these single photons sent from the ground.

So why all the excitement if we still can't teleport people? For one thing, quantum teleportation offers possibilities of creating un-hackable communications networks. Any attempts to eavesdrop on a quantum system or intercept the info being sent would cause detectable disturbances.

5. WE DISCOVERED A WHOLE NEW CONTINENT.

You'd think Earth was completely mapped out by now, but this year, an international team of scientists discovered an entirely new continent down under. Called Zealandia, this eighth continent broke off Australia millions of years ago, containing New Zealand and New Caledonia, an island further up north. More than 90 percent of Zealandia is underwater, which is why it managed to evade geographers for so long.

The team drilled cores 4000 feet underwater and gathered more than 8000 rock and sediment samples and several hundred fossils. They discovered microscopic remains of organisms that lived in warm, shallow seas as well as spores and pollen from terrestrial plants, revealing that in the past parts of Zealandia used to be above sea level.

Besides their historical importance, these findings will help us understand the planet's future prospects. The fossilized records of Zealandia's past will provide more insight into the movement of Earth's tectonic plates and the global climate system, and contribute to the computer models used to predict future climate flukes.

6. WE FOUND A MYSTERIOUS VOID IN THE GREAT PYRAMID OF GIZA.

Using a new type of tomography that employs subatomic particles called muons, scientists generated 3D images of the ancient Egyptian pyramids, including the Great Pyramid of Giza, the biggest in Egypt. The images, generated as part of the ScanPyramids project, an international endeavor launched in 2015, revealed a surprising void, suggesting an inner structure.

Despite being studied for more than a century, the Great Pyramid of Giza, built more than 4500 years ago as a burial place of pharaoh Khufu (a.k.a. Cheops), is still full of mysteries waiting to be discovered. Muons, which are byproducts of cosmic rays, pass through stones better than x-rays or other similar technology do, so they work very well for peeking inside the inaccessible ancient structures. According to the images, the void is at least 100 feet long and bears a structural resemblance to the section directly below it—the pyramid's Grand Gallery, a long area that feels like a "very big cathedral at the center of the monument," as engineer and ScanPyramids co-founder Mehdi Tayoubi described it. The discovery marks the first time a new inner structure has been located in the pyramid since the 19th century.

7. WE GREW HUMAN CELLS IN PIGS.

Researchers from the Salk Institute successfully managed to grow human cells inside pig embryos. The goal was to better understand how to develop functional and transplantable tissue or organs.

The project actually consisted of two parts. During the first part, researchers created a cross between a rat and a mouse by implanting rat cells into mouse embryos. During the second part, the team used the same technique with human cells and non-human animal hosts—such as cows or pigs, since their organs are closer in size to our own. The second feat was harder to achieve since people and pigs are further apart from each other than mice and rats are, and pig embryos develop faster than human ones.

While the experiment was successful, the technology remains very controversial, as many experts fear it could potentially lead to human-animal chimeras.

8. WE WERE WRONG ABOUT JUPITER AND SENT CASSINI ON A SUICIDE MISSION TO SATURN.

The Juno mission aimed at exploring Jupiter, which reached the target in 2016, proved that much of what we thought we knew about this planet is wrong. Turns out Jupiter's famous bands do not continue to the north and south poles. Instead, the poles are characterized by chaotic swirls and ovular features, which are Texas-sized ammonia cyclones. Ammonia, which emanates from Jupiter's great depths, plays a role in the planet's atmosphere and weather, but its levels vary greatly between different areas. Scientists still don't know whether Jupiter has a core, but they know that the pressure inside the gas giant is so strong that hydrogen, which normally is a gas, has been squeezed into a metallic fluid. The other mystery Juno may help shed some light on is Jupiter's magnetosphere, which generates spectacular auroras that are different in nature from Earth's Northern Lights.

In September, scientists deliberately sacrificed the Cassini spacecraft, which ran out of fuel after decades-long exploration of our other cosmic neighbor, Saturn. Launched in 1997 and reaching its target seven years later, Cassini tremendously expanded our knowledge about Saturn, its satellites, and our entire solar system. Thanks to Cassini, we assessed the composition of Saturn's rings and discovered that it has six moons. More interestingly, it expanded our assumptions about the habitable planets' range. We learned that a moon named Titan holds methane lakes, which could harbor a different form of life, and may have subsurface water oceans, possibly with hydrothermal vents akin to those in the Earth's undersea crusts. Now that Cassini's mission is over, all eyes are on Juno.

9. WE WATCHED TWO NEURON STARS COLLIDE AND SPEW ENOUGH GOLD TO MAKE 200 EARTHS.

Astronomers watched a never-before-witnessed cosmic phenomenon: two dead stars merging into one. It was a head-on collision of two neutron stars, which are superdense remains of previously exploded stars.

As the two stars smashed into each other in a distant galaxy 130 million light-years from Earth, they emitted gravitational waves which began traveling outward like ripples on a pond. When the waves began their cosmic journey 130 million years ago, Earth was still ruled by dinosaurs, and the complex equipment necessary to observe this phenomenon didn't exist. However, the existence of such waves was predicted by Einstein, so by the time they reached Earth, the scientists were ready with their detectors—two in the United States and one in Italy.

Moments after the detectors noticed the waves, advanced space telescopes registered a high-energy light burst. Hours later, astronomers spotted a bright new point up in the sky, emitting infrared and ultraviolet light, followed by x-rays and radio waves days later. These observations informed scientists about a "kilonova" hypothesis, which postulates that neutron star collisions generate and spew out heavy elements like gold, silver, platinum, and uranium. The blast is believed to have created some 200 Earth-masses of gold, scientists say.

10. WE DISCOVERED HUMANS ARE 100,000 YEARS OLDER THAN WE THOUGHT.

Until this year, modern humans were thought to have originated between 150,000 and 200,000 years ago, according to the oldest-known fossils of Homo sapiens found in Ethiopia. But recently unearthed remains of five early H. sapiens were dated at 300,000 years old, making our species 100,000 years older than we thought.

The new fossils were found in Morocco, on the other side of the African continent and further north than Ethiopia. Researchers now think that our ancestors may not have originated in any one specific spot in Africa, but rather evolved across the entire continent.

Before the Sahara became a desert, it sprouted forests and plains, making it possible for early humans to travel across the continent. The early hominids were likely following and hunting herds of gazelles or other animals, evolving new cognitive skills along the way, which enabled them to create more complex tools and develop advanced social behaviors. So as they spread across Africa, these early humans acquired the very traits that later came to define our species.