Scientists may have just found the longest gravitational waves yet.



Gravitational waves are ripples in the fabric of spacetime. Kicked up by massive objects, they roll through the universe like water waves on the surface of the ocean. The newfound gravitational waves are light-years long. That means it would take years for light to travel the distance of a single ripple.



Explainer: What are gravitational waves?



Whats more, these waves wash through the universe nonstop. They constantly jostle Earth and the rest of our galaxy.





Pairs of huge supermassive black holes are thought to trigger these waves. Those black-hole behemoths sit at the centers of galaxies. Scientists think that when two galaxies collide, their black holes pair up and orbit each other. This action could churn up those gravitational waves in spacetime.



Indeed, across the universe, galaxies often mingle and merge. As they do, scientists had suspected their supermassive black holes would orbit each other. In the process, these black holes would give off gravitational waves. In fact, they should pump out waves nonstop for millions of years. Many supermassive-black-hole pairs in the many merging galaxies across the cosmos would send out their spacetime ripples at once. This, scientists thought, should create a constant mishmash of very long gravitational waves.



Explainer: What are black holes?



On June 28, researchers shared the first clear evidence of such a background of gravitational waves. Those data came from several teams around the world.



Scientists must confirm that the newly spotted waves are real and that they do come from pairs of huge black holes. But if so, its miraculous, says Meg Urry. Shes an astrophysicist at Yale University. Thats in New Haven, Conn.



Confirming the new findings would offer the first proof that the biggest black holes in the cosmos can spiral into each other and merge. Its extremely interesting, Urry says. The reason? We have essentially no handle on what the most massive black holes are doing.



Catching a new kind of wave



Since 2015, scientists have spotted lots of gravitational waves. Some have come from smashups between neutron stars. Others have come from colliding black holes. But the black holes in those collisions were small, by cosmic standards. Most were less than 100 times the mass of our sun. Their smashups created blips of gravitational waves that detectors on Earth felt for mere fractions of a second.



Those supermassive black holes thought to cause the newfound gravitational waves are entirely different beasts. Each can have the mass of millions or billions of suns.



The Earth is just randomly bumping around on this sea of gravitational waves, says Maura McLaughlin. Shes an astrophysicist at West Virginia University in Morgantown.





Compared to the gravitational waves seen before, this is a very different sort of thing, says Daniel Holz. This astrophysicist works at the University of Chicago, in Illinois. He and others have used the LIGO detector to spot gravitational-wave blips from small black-hole smashups.



To find waves from supermassive black holes required a whole new technique.





Peering at pulsars



For this new research, scientists looked to objects called pulsars. Theyre spinning remnants of exploded stars. Like celestial lighthouses, pulsars emit beams of radio waves as they spin. Their beams sweep past Earth at regular intervals. Those flashing beams of radio waves are picked up, like the precise ticks of a clock, by telescopes on Earth.



Gravitational waves can stretch and squeeze the space between a pulsar and Earth. In that way, such ripples in spacetime could cause a pulsars ticks to reach Earth early or late. Scientists have now used this effect to search for the gravitational waves from supermassive black holes as they roll through space.



A project called NANOGrav has watched dozens of pulsars for 15 years. (NANOGrav is short for North American Nanohertz Observatory for Gravitational Waves.) The NANOGrav team now thinks it finally has evidence of gravitational waves from pairs of supermassive black holes. The team just shared its findings in Astrophysical Journal Letters.



Scientists searched for gravitational waves by watching dozens of spinning stars called pulsars. Here, each pulsar is shown as a blue dot against a gray illustration of our Milky Way galaxy. The yellow star (near center) shows where Earth sits in the Milky Way.NANOGrav


Its really invigorating stuff, says Michael Keith. Hes an astrophysicist at the University of Manchester in England. Hes also a member of the European Pulsar Timing Array, or EPTA.



The EPTA team spent an even longer time staring at pulsars about 25 years. We were starting to think maybe the signal is just so weak, well never ever find it, Keith says. But like NANOGrav, EPTA has now seen evidence for gravitational waves altering pulsar signals.



EPTAs results have been accepted in the journal Astronomy and Astrophysics. The European group teamed up with researchers from the Indian Pulsar Timing Array to do the work. Teams from Australia and China have now shared evidence for gravitational waves from pairs of supermassive black holes, too.



Astronomers used a variety of radio telescopes to view pulsars in their hunt for gravitational waves. One of those telescopes was the Effelsberg radio telescope (shown) in Germany.Tacken, MPIfR


Its not over yet



Some scientists had thought that supermassive black holes in merging galaxies would never draw close enough to merge. In that case, they wouldnt give off gravitational waves like the ones scientists think they have now observed.



Its actually been a sore spot for our field for many years, Chiara Mingarelli says. Mingarelli is an astrophysicist on the NANOGrav team. Shes based at Yale University.



But if the new gravitational-wave signal is real, it seems to be stronger than expected. That suggests that supermassive black holes spiraling into each other are common. This, in turn, hints that mergers between such black holes also are common.



But none of the teams sharing new data say they have for sure detected gravitational waves from huge black-hole pairs. They just say theyve found strong evidence for this. Thats because each of their observations comes with some uncertainty. In the future, the separate teams plan to join forces. Combining their data may help confirm the detection.



Still, even if the waves are real, its possible they dont come from pairs of monster black holes. Such huge black holes appear to be the simplest explanation. Still, researchers cant rule out a more exotic one. For example, the ripples might have arisen from the fast expansion of the universe just after the Big Bang.



Learning more about supermassive black holes is key to understanding the galaxies that host them. So whatever the source of the potential new gravitational waves, their future study is bound to have ripple effects.

Northern elephant seals are the true masters of the power nap.



These marine mammals swim at sea for months between brief breaks on shore. During those sea voyages, the seals snooze less than 20 minutes at a time. On average, they get a total of just two hours of shut-eye per day.



This extreme sleep schedule rivals African elephants for the least sleep seen among mammals.



Researchers shared the discovery in the April 21 Science.



Its important to map these extremes of [sleep behavior] across the animal kingdom, says Jessica Kendall-Bar. She studies marine mammals at the University of California, San Diego. Learning how much or how little sleep different animals get could help reveal why animals, including people, sleep at all.





Knowing how seals catch their zzzs also could guide efforts to protect places where they sleep.





Tracking seal sleep



Northern elephant seals (Mirounga angustirostris) spend most of the year in the Pacific Ocean. At sea, those animals hunt around the clock for fish, squid and other food.



The elephant seals, in turn, are hunted by sharks and killer whales. The seals are most vulnerable to such predators at the sea surface. So they come up for air only a couple minutes at a time between 10- to 30-minute dives.



People had known that these seals dive almost all the time when theyre out in the ocean. But it wasnt known if and how they sleep, notes Niels Rattenborg. He wasnt involved in the new study, but he has studied animal sleep. He works in Seewiesen, Germany, at the Max Planck Institute for Biological Intelligence.



Explainer: How to read brain activity



Kendall-Bars team wanted to find out if northern elephant seals really do sleep while diving. To do this, the researchers outfitted two northern elephant seals with special caps. Those caps recorded the animals brain waves, revealing when they were asleep. Motion sensors were also strapped onto the seals.



By looking at both brain-wave readings and motion data, the researchers could see how seals moved while asleep.



Kendall-Bars team took their two seals from Ao Nuevo State Park. Thats on the coast of California, north of Santa Cruz. The researchers then released the seals at another beach, one about 60 kilometers (37 miles) south of Ao Nuevo. To swim home, the seals had to cross the deep Monterey Canyon. The waters here are similar to those in the deep Pacific, where the seals swim during their months-long trips at sea.





Matching the seals brain-wave readings to their diving motions on this journey showed how northern elephant seals get their sleep on long voyages.



Deep-sea snoozes



The data revealed that when a northern elephant seal wants to sleep at sea, it first dives 60 to 100 meters (200 to 360 feet) below the surface. Then, it relaxes into a glide. As the seal nods off, it keeps holding itself upright for several minutes.



But then, the seal slips into a stage of rest known as REM sleep. During this sleep stage, the animals body becomes paralyzed. A slumbering seal now flips upside-down and drifts in a gentle spiral toward the seafloor.



A northern elephant seal can descend hundreds of meters (yards) deep during one of these naps. Thats far below the waters where sharks and killer whales normally prowl. When a seal wakes after a five- to 10-minute nap, it swims back to the surface. The whole routine takes about 20 minutes.



Explainer: Tagging through history



Now that Kendall-Bars team knew how seals moved during sleep, they could pick out naps in motion data from other seals who hadnt been outfitted with the special caps.



The researchers looked for naptime dive motions in tracking data on 334 other northern elephant seals. Those seals had been outfitted with tracking tags from 2004 to 2019. The seals movements revealed that while at sea these creatures conk out, on average, only around two hours per day.



But northern elephant seals arent short on sleep all the time. They snooze nearly 11 hours per day when they come on land to mate and molt. On the beach, they can catch up on sleep without worrying about getting eaten.



What the seals are doing [at the beach] might be something like what we do when we sleep in on the weekend, Rattenborg says.



Northern elephant seal naps are no joke. While on land, these animals can conk out for a solid 11 hours per day. But at sea, the seals catch only brief bits of sleep.Photo by Jessica Kendall-Bar, NMFS 23188



Extreme animal sleep



Northern elephant seals arent the only animals that sleep very little, at times, and then a whole lot. Rattenborgs group has found a similar sleep pattern in great frigate birds. They fly over the ocean. They can sleep while theyre flying, Rattenborg says. So on those trips, they sleep less than an hour a day for up to a week at a time, he says. Once back on land, they sleep over 12 hours a day.



Curiously, the sleep habits of northern elephant seals seem quite different from those of other marine mammals. When studied in the lab, many marine mammals sleep with just half their brain at a time. That half-awake state allows dolphins, fur seals and sea lions to constantly watch for predators. They literally sleep with one eye open.



Its pretty cool that elephant seals get by without one-sided sleep, Kendall-Bar says. Theyre shutting off both halves of their brain completely and leaving themselves vulnerable. Diving far below predators is what allows the seals to rest easy.



It seems the key to their enjoying such deep sleep is sleeping deep in the sea.

Low power. Your device will power down unless plugged into a power outlet.



How many of us have gotten such a warning from one of our digital devices? Looks like its time to plug it in and recharge the batteries with electricity.



But what is electricity?



Electricity is the term we use to describe the energy of charged particles. Electricity might be stored, like in a battery. When you connect a battery to a light bulb, electricity flows. This happens because electrical charges (electrons) are free to carry energy from the battery through the bulb. Sometimes electricity is described as the flow of electrons between neighboring atoms.





Several terms help us describe electricity and its potential to do work.



Current refers to the flow of electric charges. That is, how much charge is moving per second. When people talk about electricity, theyre usually referring to electric current.



Currents are measured in units known as amperes, or amps, for short. A single ampere of current is about 6 quintillion electrons per second. (Thats the number 6 followed by 18 zeroes.) For many devices, its common to see currents that are only thousandths of an amp, or milliamps.





Voltage offers a gauge of how much electrical energy is available to power devices. Voltage could be stored in a battery or capacitor. You may have seen a 1.5-volt label on AA and AAA batteries. In the United States, every regular electrical outlet supplies 120 volts. Large appliances like refrigerators and some air conditioners are powered by a special outlet. That outlet supplies 220 volts.



Current and voltage are related. To understand how, imagine water flowing downhill in a river. Voltage is like the height of the hill. Current is like the moving water. A tall hill could cause more water to flow. In the same way, a bigger voltage can yield a bigger electrical current.



But the height of a hill isnt the only thing that affects how the water flows. A wide riverbank would allow lots of water to flow. But if the river is narrow, the path is restricted. Not as much water can get through. And if the river gets clogged with fallen trees, the water might even stop flowing. Just like many factors affect the waters ability to flow, there are several ways that the flow of electric current can be helped or resisted.



Resistance describes how easily current can flow. A bigger voltage can lead to a bigger current, but more resistance lowers that current. Resistance varies from material to material. It also depends on the condition of a material. For instance, dry skin has a high resistance. Electricity does not easily pass across it. Getting skin wet, however, drops the resistance to almost zero.



Its important to realize that any amount of resistance may be overwhelmed by too much current trying to pass through it. As an example, electricity will not flow through wood if you simply hold the electrode of a small battery against the trunk of a tree. But a powerful bolt of lightning packs enough energy to split the tree in half.



In this simple circuit, you can see how the circuit is a loop. When the orange copper switch is open (as shown), the loop is not complete and electricity will not flow. When it is closed, electricity can flow from the battery through the circuit to turn on the light bulb.haryigit/iStock/Getty Images Plus



Circuits describe the paths that electrical currents take. Think of a circuit as a loop. In order for electricity to flow, this loop must remain closed. That means it has no gaps. When you connect a light bulb to a battery, the electricity flows from one end of the battery, through a wire, to the light bulb. Then it flows back to the battery through another wire. The circuit will continue to light the bulb as long as the loop is closed. Cut the wire and theres no longer a circuit because the path is broken.



Conductors and insulators are types of materials that respond differently to electricity. Conductors have very low resistance, so they can easily transmit a current. Most metals are very good conductors. So is saltwater. (This is why its dangerous to go swimming during a lightning storm! The chemicals in a swimming pool and the salts on our bodies make the water an especially good conductor of electricity.)



Insulators, in contrast, strongly resist the flow of electricity through them. Most plastics are insulators. Thats why electrical cords are jacketed in a layer of plastic. Electricity will flow through the copper (metal) wire inside a power cord, but the plastic coating outside makes the cord safe for us to handle.



Electricity flows through the copper wires bundled inside a power cord. The plastic coating jackets the wires so that we can safely touch the cord.Jose A. Bernat Bacete/Moment/Getty Images Plus



Semiconductors are materials that are in between conductors and insulators. In semiconductors, the flow of electricity can be precisely controlled. That makes these materials useful for directing electrical current, like tiny traffic guards, inside electronics. Computer chips depend on the ability of semiconductors to interact in complex circuits. The most common semiconductor material is the element silicon. (Not to be confused with the silicone found in flexible ice cube trays and baking tools!)



Transformers, as their name suggests, are devices that transform electrical voltage. They can be found in the box-shaped plugs at the end of device chargers. Most of these transformers convert a wall outlets 120 volts into a much, much lower level. Why? Household outlets are primed to run high-power appliances such as lamps, toasters, vacuum cleaners or space heaters. But that voltage is far more than smartphones and computers can handle. So the transformer in a charge cord steps down the electricity to a safe level that can run your device without frying it. Each device has its own specific needs for how much voltage it can handle. Thats why its important to use the right charging cable for each electronic device.



Electricity can safely power our homes and our devices when used properly. Keep in mind, however, that even common household electricity can cause severe injury or death. Always tell an adult about any broken plugs or cracked electrical wires. Dont overload circuits by plugging in too many devices at once. Never use electricity near water. And make sure that a devices power is turned off when changing its batteries. Finally, follow all of the safety warnings that come with electrical devices. Its better to be safe than to risk injury or fire.

Bacteria can have superpowers. Some flourish in almost any environment. Others can transform toxic materials into harmless sludge. A bacterium called Shewanella oneidensis can do both. But this microbe also has a much rarer superpower: It absorbs and produces electricity. In fact, new research suggests, these bacteria may be able to use energy collected from wind or solar sources to make fuels to run vehicles and more.



I think of these organisms as eating electricity, says Annette Rowe. Shes a microbiologist at the University of Cincinnati in Ohio. Her team has just identified which genes the microbe uses to gobble electricity.



Explainer: Understanding electricity



Electrons are negatively charged particles. A moving stream of them creates an electric current. Scientists already knew that Shewanella can move electrons back and forth across its cell wall. But they didnt know exactly how the microbes controlled their current, Rowe says.





The pathway for getting the electrons in and out of the cell is like a wire, says Rowe. It allows current to flow from the inside to the outside. Reverse the flow, she says, and you can drive electrons into the cell. The cell could then use those electrons to do some other job, such as generate current. Or it could store the energy to use later. Those electrons could later be used to make fuel, for example.



Rowe knew that Shewanellas cellular wire had to be controlled by genes. But which ones?



Buz Barstow was able to help. He is a biological engineer at Cornell University. Its in Ithaca, N.Y. Earlier, he had made a list of nearly 4,000 of this bacteriums genes. That list also included mutations, or changes, in those genes. Rowe tested these mutants to find the genes that made up Shewanella’s cellular “wire.”



Explainer: What are genes?



Within a cell, a gene can deleted. For the new study, Rowe and her colleagues tested groups of bacteria with groups of deleted genes. Their goal: to see which deleted genes allowed the bacteria to pull in electrons. These were likely genes involved in making the cell’s “wire.”



That was no easy task. It was really tricky to look for electron flow and track the electrons, she says. But in time they devised a clever test. They grew the different mutated bacteria on glass covered by a thin metal film. Then they attached a wire to the bacteria. When they sent an electric current through the wire, they could measure how much the bacteria absorbed or added. If electrons didnt flow, the scientists knew the deleted genes must have been the ones needed for electron flow. 



In time, they narrowed in on five such genes that Shewanella apparently uses to absorb electrons. Each gene tells the cell how to make a protein. Some of those proteins likely grab electrons and bring them into the cell. Others may send signals within the cell that guide the process. Still others can likely expel electrons from the cell.





Bacterial biofuels



Scientists see many ways to use electric microbes. One would be to make biofuels. These differ from fossil fuels, such as coal and natural gas. (Fossil fuels are rich in carbon from decayed remains of ancient living things.) Ethanol, which can be made from corn or sugarcane, is a biofuel that can be added to standard gasoline. Cars that run on diesel can be adapted to run on another biofuel. Called biodiesel, it is fuel made from vegetable oil or animal fats.



Biofuels get their carbon from sources like plants or animal wastes. One day, they may even get their carbon with the help of bacteria, says Rowe.



This technician holds a biofuel sample, an alternative to fossil fuels. One day bacteria may be able to supply the power or the carbon needed to unleash a new wave of such renewable fuels.Sue Barrt/Image Source/Getty Images Plus



Shewanella is among bacteria thatcan pluck carbon atoms out of carbon dioxide. They can use it to create other, larger molecules that could be burned as a biofuel. And powered by the electrons it gobbles, Shewanella could keep making these molecules, Rowe says.



Knowing which genes drive the electron-eating could help scientists develop new biofuels, says Rowe. Even better would be if the electrons that feed the bacteria come from wind or solar power. Such sources could power the biofuel-making process without adding warming carbon dioxide to the air.



Elad Noor is an environmental scientist. He works at the Weizmann Institute of Science. Its in Rehovot, Israel. There, hes helping to develop new ways to fix carbon that is, to pull carbon from carbon dioxide to build other chemical compounds. Using bacteria to create biofuels is attractive because the bacteria can regenerate and should be able to repurpose the carbon. Soring energy in bacteria also would be green, he adds. After all, the microbes dont need dangerous metals, as a normal battery would.



However, working with living organisms is complicated, he warns. Biological systems are hard to predict, he says. There are ways to store energy that are much more efficient.



The genes that Rowes team found in Shewanella show up in other bacteria. The group plans to search for others that can store or release electrons. Rowe also wants to try to improve Shewanellas abilities, because these are the organisms we know the most about.

Excavations in an Israeli sinkhole have turned up a previously unknown Stone Age group of hominids. Its members contributed to the evolution of our genus, Homo. Remains at the new site, known as Nesher Ramla, come from 140,000 to 120,000 years ago. This hominid joins Neandertals and Denisovans as a third Euro-Asian population that belong to our genus. Over time, researchers say, they culturally mingled with and possibly interbred with our species, Homo sapiens.



Hominid fossils also have been found in three Israeli caves. Some date to as early as 420,000 years ago. They likely come from an ancient population of the hominid group whose remains have just turned up at Nesher Ramla. Thats the conclusion of a new study. Paleoanthropologist Israel Hershkovitz led that study. He works at Tel Aviv University in Israel.



Scientists Say: Hominid



His team hasnt assigned a species name to the newfound hominids. The researchers simply refer to them as Nesher Ramla Homo. These folk lived in the Middle Pleistocene. It ran from about 789,000 to 130,000 years ago. Back then, interbreeding and cultural mixing took place among Homo groups. This happened so much, the team notes, that it prevented the evolution of a distinct Nesher Ramla species.





Two studies in the June 25 Science describe the new fossils. Hershkovitz led one team that described the hominid remains. Archaeologist Yossi Zaidner of the Hebrew University of Jerusalem led a second team. It dated rock tools found at the site.



The new fossils further complicate the human family tree. That tree has grown more complex in the past six years or so. Its branches hold several newly identified hominids. They include H. naledi from South Africa and the proposed H. luzonensis from the Philippines.



Nesher Ramla Homo was one of the last survivors of an ancient group of [hominids] that contributed to the evolution of European Neandertals and East Asian Homo populations, Hershkovitz says.





Lots of cultural mixing



Work at Nesher Ramla uncovered five pieces of a skull. They come from the braincase. (As the term implies, this bone encased the brain.) A nearly complete lower jaw also turned up. It still held a lone, molar tooth. These fossils in some ways look like Neandertals. In other ways, they better resemble remains of a pre-Neandertal species. It was called Homo heidelbergensis. Scientists think those individuals occupied parts of Africa, Europe and possibly East Asia as early as 700,000 years ago.



Some Homo fossils from sites in China also show a mix of traits that resemble features of the Nesher Ramla fossils, Hershkovitz says. It may be, he says, that ancient Homo groups with roots at this site may have reached East Asia and mated with hominids there.



But Nesher Ramla folk didnt have to go that far to interact with other hominids. Stone tools at the Nesher Ramla site match those of about the same age made by nearby H. sapiens. Nesher Ramla Homo and early members of our species must have exchanged skills on how to make stone tools, Hershkovitz concludes. These folk also may have interbred. DNA from the new fossils might have confirmed that. For now, however, efforts to get DNA from the Nesher Ramla fossils have failed.



Along with the new fossils, Hershkovitzs team dug up some 6,000 stone artifacts. They also found several thousand bones. Those came from gazelles, horses, tortoises and more. Some of those bones showed stone-tool marks. That would suggest the animals had been butchered for meat.



These stone tools were made by an ancient population in the Middle East. Those individuals belonged to our genus, Homo. The tools resemble those made around the same time by nearby H. sapiens. This suggests the two groups had close contacts.Tal Rogovski



John Hawks at the University of WisconsinMadison did not take part in the new research. But as a paleoanthropologist, hes familiar with ancient hominids and artifacts from their time. Hawks is intrigued that stone tools usually linked with our species turned up among such distinctive-looking non-human fossils. Thats not a smoking gun proving there were close interactions between Nesher Ramla Homo and [our species], he says. But, he adds, it does suggest that.



The Nesher Ramla fossils fit a scenario in which the Homo genus evolved as part of a community of closely related Middle Pleistocene folk. These would have included Neandertals, Denisovans and H. sapiens. Groups at southern sites moved into much of Europe and Asia during relatively warm, wet times, writes Marta Mirazn Lahr. Shes a paleoanthropologist at the University of Cambridge in England. She wrote a commentary that accompanied the two new studies.



Lahr says it appears that ancient groups interbred, became fragmented, died out or recombined with other Homo groups along the way. All of this social mixing, she says, may help explain the wide variety of skeletal looks seen in European and East Asian fossils from our genus Homo.

A group ofwandering wildelephants, nicknamed"The Northbound Wild Elephant Eating and Walking Tour,"have become an overnight Internet sensationin China and globally.The packfirstcaptured the attention of the locals in March2020, after theysuddenly left their home in theXishuangbanna National Nature Reserve.

Over the past six months, a massive campaign has revved up to get COVID-19 vaccines into the arms of people across the globe. Doctors initially rolled out the immunizations to older people and those with underlying health problems. Now, as teens roll up their sleeves and younger kids prepare to do so some have started asking a big question: Will we all need booster vaccines?



No one knows if booster shots will be needed, says Kirsten Lyke. Shes an expert in vaccine science. She works at the University of Maryland School of Medicine in Baltimore. But if boosters are needed, it shouldnt be too surprising. People need a new shot in the arm every year to fend off influenza.



Explainer: What is a vaccine?



SARS-CoV-2 is the virus that causes COVID-19. As with the flu virus, the new coronavirus has been mutating. Newly emerging variants respond to the original vaccines. But theres concern those variants will eventually get around the immunity that our bodies developed to the first versions of the vaccine. And that may mean boosters are needed.





The good news: More than half of U.S. residents have gotten at least one dose of a COVID-19 vaccine. As a result, U.S. cases and deaths have plunged to their lowest levels since March 2020.



Heres what we know so far about the possible need for booster shots. 



Immunity lasts at least six months



Whether and when people might need a booster shot rests largely on how long the bodys immune system protects against us becoming very ill. For COVID-19, this protection lasts at least six months, researchers say. It could possibly last much longer. Data on this have been emerging from people who were infected last year.



Once the virus gains a toehold, the body unleashes a wave of immune troops to fight it off. They include antibodies and so-called T cells. Antibodies typically attack the virus itself. T cells raise additional alarm bells or kill infected cells. Together, antibodies and T cells defeat the virus and then help the immune system form a memory of the virus, explains Ali Ellebedy. Hes an immunologist. He works at Washington University School of Medicine in St. Louis.



See all our coverage of the new coronavirus outbreak



That immune memory is crucial. It turns on the whole protection cycle again if and when someone gets exposed to the virus once more.



So far, Ellebedy says, immune memory to SARS-CoV-2 has largely been following the rules at least for most people.



Nearly everybody has been developing an immune memory to the coronavirus, studies are finding. Some antibody-producing cells continue to work long after the virus has left the body. That should protect people who encounter SARS-CoV-2 again. Ellebedy found signs of these cells in people who had recovered from COVID-19. Those with even mild symptoms had antibody-producing immune cells in their bone marrow 11 months after infection. Ellebedy was part of a team that reported this May 24 in Nature.



Growing evidence now suggests that vaccines offer similar if not better protection. If true, boosters might not be needed for some time. Right now, things look pretty good, Lyke says. People who got the Moderna vaccine still had high levels of antibodies six months after getting their second dose. Researchers shared the finding in April. And a jab of Pfizers vaccine remained 91.3 percent effective against COVID-19 symptoms after six months. Pfizer shared this in an April 1 news release.  



Still, we dont know how any of these COVID-19 vaccines perform past the one-year mark, Lyke says. Scientists are keeping a close eye on them, though.





The role of coronavirus variants



Available vaccines still protect people from the worst of COVID-19. But that might not always be true. COVID-19 vaccines already show signs they can be less effective against some new variants.



If it werent for the variants, I dont think we would be talking about potentially boosting, says Ellebedy. What we are seeing so far is that the vaccine is really robust. So why would we even need a booster if the virus doesnt change?



Companies are already testing booster shots to fight some variants. Some tests have focused on the so-called beta variant. It first emerged in South Africa. Early results from Moderna, for instance, hint that people who receive its booster shot against a viral protein in the beta variant develop antibodies to that variant. The antibodies sparked by this booster were better at stopping the variant from infecting lab-grown cells than were ones from people who got a third dose of the original vaccine.  



For now, no one knows what the best variant booster might look like, says Jerome Kim. Hes a vaccine scientist and director-general of the International Vaccine Institute. Its headquarters is in Seoul, South Korea.



Gaining immunity to the new coronavirus may take more than one course of shots. It may require booster shots on some regular basis, too.SDI Productions/E+/Getty Images Plus



Mix and match for vaccines?



To prepare for a future where people might need COVID-19 boosters, the U.S. National Institute of Allergy and Infectious Diseases launched a clinical trial on June 1. It will test the value of mixing and matching COVID-19 vaccines.



The big question is whether this approach will strengthen the immune response, says Lyke. Shes a researcher leading the trial. These scientists want to know what will happen if someone is given an mRNA vaccine such as Modernas or Pfizers and then is given a different type as a booster (such as Johnson & Johnsons vaccine). Can we increase [the immune response]? Lyke asks.



Its not a crazy idea. Mixing different types of Ebola vaccines or HIV vaccines, for example, can trigger stronger immune responses than getting multiple doses of the same vaccine. The idea is that a second type of shot will activate some extra part of the immune system, Lyke explains. That way, she hopes, You get the best of both.



Early results from a similar trial being conducted in the United Kingdom hint that the answer for COVID-19 shots is yes.

Dont watch TV close to bedtime. Put away your phone, too, or you may have trouble falling asleep. You may not realize it, but the blue light from device screens and even common lamps will confuse your brains internal 24-hour clock. Even white light contains these blue wavelengths. And when blue light enters the eyes, your brain gets the message that it needs to stay awake. But a new type of lighting appears to get around these sleep-challenging effects so you can nod off easily at bedtime.



This new light-emitting diode, or LED, might someday deliver the glow in lamps and other types of home lighting, its developers say. It might even find use in TV, laptop and smartphone screens, says Jakoah Brgoch. Hes a chemist at the University of Houston, Texas. He also helped design the new lighting technology.



He and fellow University of Houston chemist Shruti Hariyani have been studying the properties of phosphors. These substances glow when hit with light.



Explainer: Our bodies internal clocks





Light shines through the lens of an LED, usually a plastic bulb. Behind the scenes is an LED chip, which has small light-emitting diodes attached to a printed circuit board. When the chip is coated with powdered phosphors, the color of the light shining through the lens changes. The Houston team created a new phosphor to make their LED shine with a warm white light. Here, warm means the light contains less of the short, blue wavelengths that can mess with sleep.



Those same blue wavelengths are found in sunlight. And they tell your internal body clock that its time to be awake. Normally that body clock winds down as daylight fades. Melatonin is a hormone produced at night. It helps bring on sleep unless blue light tells your body otherwise. Blue light suppresses the melatonin hormone.



Explainer: What is a hormone?



And our bodies may well get confused if its late and our eyes remain bathed in blue light from devices or indoor lighting. Even though your body craves sleep, its still getting that signal for wakefulness.



Most modern screens and lighting systems use blue LEDs. They are energy efficient, long-lasting and cost little. But, Hariyani says, you have to be okay with the negative side effects [of their light] or fix it.



Shes part of a team thats choosing to fix it.





How to lose the blues



A new violet LED, shown here in a drawing, uses red, green and blue-emitting phosphors to combine the colors of the visible spectrum and create white light.S. Hariyani/University of Houston



Software helps some devices emit less blue light. For example, the iPhones night mode shifts its color palette. But this makes images look more red than normal, so users give up color quality. Plus, the LEDs in this and other smartphones still emit enough blue light to affect the bodys internal clock and melatonin production. People can block out some blue light by wearing yellow glasses near bedtime. However, this too will distort the hues in whatever youre viewing.



Says Brgoch, We wanted to know: Can we get to a high-quality light bulb with warmer and better quality light?



LEDs create white light by mixing red, green and blue hues. While these same primary colors of pigment in paint or crayons mix to make black, light works the opposite way. The white light shining out of an LED comes from the bulb color plus the colors of the phosphors used to coat the LED. Common house lighting uses blue LEDs coated with phosphors whose colors add to the LEDs colors to make white light.



A rarer type of LED has a violet bulb. Places such as museums and clothing stores install white lighting made using violet LEDs. Thats because these are designed to show an object’s true color better than the more common bluer LEDs used in most home lights. One drawback is that violet LEDs cost more. Still, Brgoch and Hariyani chose them for their prototype to get the best color.



Used in the new light, this phosphor glows blue when lit with a violet LED.S. Hariyani and J. Brgoch/University of Houston



To reduce their LEDs blue emissions, the chemists first altered a white powdered crystal that didnt glow on its own. They added a bright silver-colored element to the powders structure. This europium turns the crystal into a phosphor. Europium often is added to lighting phosphors because it helps boost the blue part of an LEDs glow. In this case, it made a true, high-quality blue good for use in an LED. That blue can combine with other colors to make white light.



The Houston team tested the new phosphor to make sure it wouldnt break down easily. They exposed it to heat and water. Not only did the phosphor continue to glow at the same intensity, but its color remained steady. Having all of these properties at once makes it superior to many other phosphors, Hariyani says.



Then they mixed the blue phosphor with red and green ones to create white light. The chemists added this combination to a modified violet LED. Compared to standard violet LEDs, this new one emits far less intense blue light.



Good white and good night?



A mixture of the new blue phosphor, together with red- and green-emitting ones, produces this warm white light when lit by a violet LED.S. Hariyani and J. Brgoch/University of Houston



Theres maybe a dozen phosphors used around the world in lightbulbs, notes Brgoch. To find something new thats on par with what you can buy is fantastic. And, he adds, its lower production of short, blue wavelengths should reduce its effect on someones nighttime secretion of melatonin.



But other aspects of light also influence the body, warns Mariana Figueiro. Her work at Mount Sinai Hospital in New York City focuses on how light affects the body clock and melatonin.



Brightness and colors of light other than blue such as green and yellow also affect the bodys natural readiness for sleep, Figueiro notes. To leave nighttime melatonin alone, she explains, A light source needs to have both low light levels and less blue light. She wonders if everyday lamps and screens could be dim enough not to interfere with the body’s internal clock and still be bright enough for practical use. Still, she says, its certainly worth studying.



To know if the new LED could help people who want to sleep better, scientists will have to measure its effect on melatonin.



This is science that is still relatively new to us, Brgoch says. As such, he says it will take some time for scientists to fully understand how to use the new LEDs in household items.



He and Hariyani shared their findings April 14 in ACS Applied Materials and Interfaces.

A dose of antibiotics seems to help some corals recover from a mysterious tissue-eating disease. And yes, theyre the same antibiotics used in people.



Divers discovered the coral disease in 2014. It was afflicting reefs near Miami, Fla. Nicknamed skittle-D, it appears as white lesions that rapidly eat away at coral tissue. The disease has no cure. It currently plagues nearly all of the Great Florida Reef, which spans some 580 kilometers (360 miles). In recent years, skittle-D has spread to reefs in the Caribbean.



Now, a type of coral with skittle-D just off the Florida coast has improved several months after being treated with amoxicillin. Researchers reported the findings April 21 in Scientific Reports. The deadly disease came back on some treated coral over time. But the results provide a spot of good news.



Antibiotic treatments give the corals a break, says Erin Shilling. She works as a coral researcher at Florida Atlantic University in Fort Pierce. Its very good at halting the lesions its applied to.



Treatment with an antibiotic paste (white bands, left) stopped a tissue-eating lesion from spreading over a great star coral colony up to 11 months later (right).E.N. Shilling, I.R. Combs and J.D. Voss/Scientific Reports 2021



Testing treatments



What causes skittle-D remains unknown. So scientists are left to treat the lesions it causes through trial and error. Two treatments show promise. In one, divers apply a material known as a chlorinated epoxy. In another, divers use an amoxicillin paste. 





Lets learn about coral reefs




Shilling and her colleagues wanted to see if either worked as well as some people have been saying. In April 2019, her team found 95 lesions on 32 colonies of great star corals. The scientists dug trenches to surround the lesions. Trenches separate diseased coral tissue from healthy tissue. The team then filled the moats and covered the lesions with the paste or epoxy. Scientists monitored the corals for 11 months.



Within about three months, some 95 percent of lesions treated with amoxicillin had healed. Meanwhile, only about 20 percent of the epoxy-treated lesions had healed in that time. That rate was no better than in untreated lesions. 



But a one-and-done treatment doesnt stop new lesions from popping up, the team found. Some key questions also still need answers, the scientists note. For instance, how long does the treatment work and in which coral species. Scientists are also trying to figure out what side effects antibiotics might pose to the corals.






Cause for hope



Erins work is fabulous, says Karen Neely. She is a marine biologist at Nova Southeastern University in Fort Lauderdale, Fla. Neely and her team see similar results in their two-year experiment at the Florida National Marine Sanctuary. Her group used the same paste and epoxy treatments on more than 2,300 lesions. Those lesions affected some 1,600 coral colonies.The antibiotic was more than 95 percent effective across all eight species tested, Neely says. New lesions popped up after the initial treatment. But covering those new patches with paste appeared to stop skittle-D from coming back over time. Her teams findings are undergoing peer-review in the journal Frontiers in Marine Science.Overall, putting these corals in this treatment program saves them, Neely says. We dont get happy endings very often, so thats a nice one.

Donut lovers,rejoice!Friday,June 4, 2021, is National Donut Day. That means it is your civic duty to consume at least one oreven a dozen of the delicious confections. The fun US holiday, observed annually on the first Friday of June,was startedin 1938 by theSalvation Army to help raisefunds forthose in need.

While scientists have managed torecover and examine thousands of meteorites,finding their origin or even whether they are from icy comets or rocky asteroidshasproved elusive.Now, for the first time, a team of internationalresearchershastraced the source ofa boulder-sized rockthat landed in Botswanato an asteroid named Vesta. Boasting adiameter of about326miles, it is one of the largest and brightest rocksin theasteroid beltthat circles the Sun between Jupiter and Mars.

Climate change is coming for glaciers. Many are losing ice as summers get warmer and winters are bringing less fresh snow to build them up again. But to know when exactly a glacier will be gone, scientists first have to know how big it is. That why Ellery McQuilkin, 16, trekked up a glacier with a large drill in tow. To find out how big the glacier was, she drilled holes in it.



Explainer: Ice sheets and glaciers



Ellery is a junior at Lee Vining High School in California. I live right near Yosemite National Park, she notes. I’ve spent a lot of time backpacking and hiking so I’ve sort of been around glaciers a fair amount. Ellery also is interested in climate change. Scientists have already reported big irreversible effects of climate change on glaciers, she says. Thats even true near her, where she says glaciers are actually melting away. At this point, she fears, it could be too late to do anything to save them.



Her town of Lee Vining is very close to four small glaciers: the Conness, Dana, Kuna and Koip. No one actually knows how big or small these are, she says. To calculate their volume, one could theoretically multiply their height times depth times width. But depth is hard to find when only the top of a glacier is visible. The rock underneath might host sharp peaks or deep valleys. It might even be totally flat. What the bottom of the glacier looks like, there’s no way to visually see that, Ellery says.



To gauge that depth, she decided to try drilling test holes to the rock below.



Ellery poses on the Dana Glacier in California. She hauled a steam drill up to the glacier on her back, then used it to estimate the ice fields size. Geoff McQuilkin



Measuring thin ice



Scientists have other ways to calculate how much ice is in a glacier. But those ways are designed with large glaciers in mind. For small ones like those near Ellery, those techniques dont really work. So to find the volume of the small glacier on Mount Dana, she brought a steam drill. It weighs about 15.8 kilograms (35 pounds). Ellery could carry it up the mountain to the glacier on her back.





So there’s this big boiler. You fill it up with water, Ellery explains, and you heat it up. The drills hose then shoots hot steam at high pressure to melt a very small hole in the ice. Ellery used the drill to poke holes all the way through the glacier at some points. Where the glacier was thicker, she drilled just partway through.





She then used the depths she measured with the drill along with a computer model to calculate the volume of the Dana glacier. Her tally comes to about 596,000 cubic meters (778,500 cubic yards). Thats enough ice to fill a medium-sized football stadium. The deepest part of the glacier is around 30 meters (100 feet).



This glacier is very small and shrinking. Basically, in eight years, the Dana glacier will have melted away almost entirely, Ellery projects. And the region will lose more than a white field of ice on Mount Dana. The glaciers yearly meltwater supports a freshwater stream on which many animals and plants depend. It is really just sad that this massive shaping force is going to disappear entirely, she says. Adding to her frustration is that people really aren’t even aware that it’s happening.



The Dana glacier sits under a large rock shelf. That shades it, allowing the ice to stay cooler than the mountain nearby. But thats not enough to save the glacier, which Ellery estimates will be gone in eight years. Geoff McQuilkin



The teens ice-cold project earned her a spot at the Regeneron International Science and Engineering Fair. Created by Society for Science, this yearly competition brought together nearly 2,000 finalists in 2021. They came from 64 countries, regions and territories to show off their science fair projects. (The Society for Science also publishes Science News for Students.) This years ISEF competition moved online due to the COVID-19 pandemic. There, Ellerys project earned her first place in the Earth and Environmental Sciences category and $5,000.



Ellery hopes to continue measuring Dana glacier, as well others near her town. She wants to find points where people took old photos of the glaciers and compare those to new images. That should offer this very clear documentation of the glacier as it melts, she says. Its probably too late to save the Dana glacier, she says. But if she can document how glaciers are changing, she thinks she might just spur people to act in time to save others.

Memorial Day, whichwill be celebrated onMay 31, 2021,is one of the most important American holidays.Observed annually on the last Monday ofMay, it honors the brave men and women of theUS Army, Navy, Marine Corps, National Guard, Air Force, and the Coast Guard whosacrificed their lives to defend America's freedom. Meanwhile,Veterans Day, which takes place each yearon November 11, honorsall veterans living or deadbut mainly givesthanks to livingveteranswho served their country honorably during war or peacetime.

Lightning may play an important role in clearing the air of pollutants.



A storm-chasing airplane has shown that lightning can forge large amounts of oxidants. These chemicals cleanse the atmosphere by reacting with pollutants such as methane. Those reactions form molecules that dissolve in water or stick to surfaces. The molecules can then rain out of the air or stick to objects on the ground.



Supercell: Its the king of thunderstorms



Researchers knew lightning could produce oxidants indirectly. The bolts generate nitric oxide. That chemical can react with other molecules in the air to make some oxidants. But no one had seen lightning directly create lots of oxidants.





A NASA jet got the first glimpse of this in 2012. The jet flew through storm clouds over Colorado, Oklahoma and Texas in both May and June. Instruments on board measured two oxidants in the clouds. One was hydroxyl radical, or OH. The other was a related oxidant. Its called the hydroperoxyl (Hy-droh-pur-OX-ul) radical, or HO2. The airplane measured the combined concentration of both in the air.



Explainer: Weather and weather prediction



Lightning and other electrified parts of the clouds sparked the creation of OH and HO2. Levels of these molecules rose to thousands of parts per trillion. That may not sound like much. But the most OH seen in the atmosphere before was only a few parts per trillion. The most HO2 ever seen in the air was about 150 parts per trillion. Researchers reported the observations online April 29 in Science.



We didnt expect to see any of this, says William Brune. Hes an atmospheric scientist. He works at Pennsylvania State University in University Park. It was just so extreme. But lab tests helped confirm that what his team saw in clouds was real. Those experiments showed electricity really could generate lots of OH and HO2.



Scientists Say: Climate



Brune and his team calculated how much of the atmospheric oxidants that lightning could produce around the world. They did this using their storm-cloud observations. The team also accounted for frequency of lightning storms. On average, some 1,800 such storms are raging around the globe at any point in time. That led to a ballpark estimate. Lightning could account for 2 to 16 percent of atmospheric OH. Observing more storms could lead to a more precise estimate.



Knowing how storms affect the atmosphere may become even more important as climate change sparks more lightning.

This week's severewinter storm,which dumped record amounts of snow in the Mid-Atlantic and the Northeast, had most residents scrambling for the safety and warmth of their homes. However, theanimals at theSmithsonian's NationalZoo were not going to letWashington, DC's firstsignificant snowfall in two years go to waste.