Flowing Fire? How Yosemite Waterfall Appears to Burn

It may look like a ribbon of cascading lava, but a so-called "firefall" in Yosemite National Park is actually a regular waterfall illuminated by the bright light of the setting sun.

Almost every mid-to late-February, Yosemite's Horsetail Fall — a seasonal waterfall that flows when the snowpack melts in the winter and early spring — glows a bright and fiery orange.

However, the firefall happens only under the right conditions. For starters, the sky needs to be clear. In addition, the sun needs to set at the right angle in the western sky; this creates the illusion that the waterfall is burning, Live Science reported previously.

"Even some haze or minor cloudiness can greatly diminish or eliminate the effect," the National Park Service wrote on its website.

The sight, which now attracts thousands of people annually, is one to behold. But it's short-lived, happening for only about 10 minutes each day, Live Science reported.

Yosemite visitors hoping to catch an eyeful of the firefall are in for a treat this year, officials said.

"The waterfall is bigger than it has been in a long time due to all the rain and snow we have received," National Park Service spokesman Scott Gediman told CNN.

Many people have taken to social media to share photos of the astounding firefall. The U.S. Department of the Interior tweeted, "Every February, a rare phenomenon makes Horsetail Fall @Yosemitenps glow like fire. Pic from Saturday by Ray Lee #California #firefall."

Horsetail Fall flows over the eastern edge of El Capitan in Yosemite Valley. The firefall is best seen from the El Capitan picnic area, located west of Yosemite Valley Lodge and east of El Capitan, National Park Service officials reported.

Help Me, Obi-Wan! New Hologram Technology Mimics 'Star Wars'

Princess Leia's holographic plea in the classic film "Star Wars" inspired researchers to work toward a device that could project real-life sci-fi holograms. Now, the futuristic 3D imaging may be one step closer to reality.

A team of physicists at the Australian National University (ANU) invented a tiny device that creates the highest-quality holographic images ever achieved, the scientists said.

Study lead researcher Lei Wang, a Ph.D. student at the ANU Research School of Physics and Engineering, said he first learned about the concept of holographic imaging from the "Star Wars" movies. However, these futuristic-looking 3D images could be used for more practical ends than sending messages from a galaxy far, far away.

"While research in holography plays an important role in the development of futuristic displays and augmented reality devices, today we are working on many other applications, such as ultrathin and lightweight optical devices for cameras and satellites," Wang said in a statement.

Photographs and computer screens display information only in 2D, limiting views to flat images. Holograms, however, allow for the storage and reproduction of all information in 3D, and the technology relies on the ability to accurately manipulate light in three dimensions, the researchers said.

The ANU invention uses a new nanomaterial to create the 3D projections. Millions of tiny silicon pillars, each up to 500 times thinner than a human hair, act as pixel projectors to create the light-based 3D images, said co-lead researcher Sergey Kruk, a professor at the ANU Research School of Physics and Engineering.

"This new material is transparent, which means it loses minimal energy from the light, and it also does complex manipulations with light," Kruk said in the statement.

In lab tests, the device created tiny holograms ranging in size from 0.03 inches to 0.2 inches (0.75 millimeters to 5 mm) wide, at a distance of 0.4 inches (10 mm). While the technology is not yet ready to replace computer screens, with further research, the device could lead to new and better holographic technologies, the scientists said.

The device's ability to display the 3D holograms is only part of what makes it innovative, however, Wang said. Due to its miniature size, the invention could replace bulky camera components or help space missions by reducing the size and weight of optical systems, he said.

Details of the new study were published online Dec. 20 in the journal Optica. 

RoboDragonfly: Tiny Backpack Turns Insect into a Cyborg

Scientists look to flying animals — birds, bats and insects — for inspiration when they design airborne drones. But researchers are also investigating how to use technology to interact with, and even guide, animals as they fly, enhancing the unique adaptations that allow them to take to the air.

To that end, engineers have fitted dragonflies with tiny, backpack-mounted controllers that issue commands directly to the neurons controlling the insects' flight.

This project, known as DragonflEye, uses optogenetics, a technique that employs light to transmit signals to neurons. And researchers have genetically modified dragonfly neurons to make them more light-sensitive, and thereby easier to control through measured light pulses. 

Dragonflies have large heads, long bodies and two pairs of wings that don't always flap in sync, according to a 2007 study published in the journal Physical Review Letters. The study authors found that dragonflies maximize their lift when they flap both sets of wings together, and they hover by flapping their wing pairs out of synch, though at the same rate.

Meanwhile, separate muscles controlling each of their four wings allow dragonflies to dart, hover and turn on a dime with exceptional precision, scientists found in 2014. Researchers used high-speed video footage to track dragonfly flight and build computer models to better understand the insects' complex maneuvers, presenting their findings at the 67th Annual Division of Fluid Dynamics meeting, according to a statement released by the American Physical Society in November 2014.

DragonflEye sees these tiny flight masters as potentially controllable flyers that would be "smaller, lighter and stealthier than anything else that's manmade," Jesse Wheeler, a biomedical engineer at the Charles Stark Draper Laboratory (CSDL) in Massachusetts and principal investigator on the DragonflEye program, said in a statement.

The project is a collaboration between the CSDL, which has been developing the backpack that controls the dragonfly, and the Howard Hughes Medical Institute (HHMI), where experts are identifying and enhancing "steering" neurons located in the dragonfly's nerve cord, inserting genes that make it more responsive to light.

"This system pushes the boundaries of energy harvesting, motion sensing, algorithms, miniaturization and optogenetics, all in a system small enough for an insect to wear," Wheeler said.

Even smaller than the dragonfly backpack are components created by CSDL called optrodes — optical fibers supple enough to wrap around the dragonfly's nerve cord, so that engineers can target only the neurons related to flight, CSDL representatives explained in a statement.

And in addition to controlling insect flight, the tiny, flexible optrodes could have applications in human medicine, Wheeler added.

"Someday these same tools could advance medical treatments in humans, resulting in more effective therapies with fewer side effects," Wheeler said. "Our flexible optrode technology provides a new solution to enable miniaturized diagnostics, safely access smaller neural targets and deliver higher precision therapies."

'Bat Bot' Can Pull Off Impressive Aerial Acrobatics

Whether they're swooping around to catch dinner or delicately hanging upside down to sleep, bats are known for their acrobatic prowess. Now, scientists have created a robot inspired by these flying creatures. Dubbed the "Bat Bot," it can fly, turn and swoop like its real-life counterpart in the animal kingdom.

Since at least the time of Leonardo da Vinci, scientists have sought to mimic the acrobatic way in which bats maneuver the sky. Someday, robotic bats could help deliver packages or inspect areas ranging from disaster zones to construction sites, the researchers said.

"Bat flight is the Holy Grail of aerial robotics," said study co-author Soon-Jo Chung, a robotics engineer at the California Institute of Technology and a research scientist at NASA's Jet Propulsion Laboratory, both in Pasadena. 

Robo-Bees Could Aid Insects with Pollination Duties

Mini drones sporting horsehair coated in a sticky gel could one day take the pressure off beleaguered bee populations by transporting pollen from plant to plant, researchers said.

Roughly three-quarters of the world’s flowering plants and about 35 percent of the world's food crops depend on animals to pollinate them, according to the U.S. Department of Agriculture.

Some of nature's most prolific pollinators are bees, but bee populations are declining around the world, and last month, the U.S. Fish and Wildlife Service listed a native species as endangered for the first time.

Now, researchers from Japan said they've taken the first steps toward creating robots that could help pick up the slack from insect pollinators. The scientists created a sticky gel that lets a $100 matchbox-size drone pick up pollen from one flower and deposit it onto another to help the plants reproduce.

"This is a proof of concept — there's nothing compared to this. It's a totally first-time demonstration," said study leader Eijiro Miyako, a chemist at the National Institute of Advanced Industrial Science in Tsukuba, Japan. "Some robots are expected to be used for experiments in pollination, but no one has tried yet."

A happy accident

The key innovation of the new study, published today (Feb. 9) in the journal Chem, is the so-called ionic liquid gel, but according to Miyako it was more down to luck than design. The gel was actually the result of a failed attempt to create electrically conducting liquids and had sat forgotten in a desk drawer for nearly a decade.

But after eight years, it still hadn't dried out, which most other gels would have done, and was still very sticky, Miyako said. Fortunately, this discovery coincided with Miyako watching a documentary that detailed concerns about insect pollinators.

 "I actually dropped the gel on the floor and I noticed it absorbed a lot of dust, and everything linked together in my mind," he told Live Science.

The gel has just the right stickiness, meaning it can pick up pollen but is not so adhesive that it won't let the grains go.

The scientists next tested how effectively the gel could be used to transport pollen among flowers. To do so, the researchers put droplets of the material on the back of ants and left the insects overnight in a box full of tulips. The next day, the scientists found that the ants with the gel had picked up far more pollen grains than those insects that lacked the sticky substance.

In a side experiment, the researchers found that it was possible to integrate photochromic compounds, which change color when exposed to UV or white light, into the gel. Scientists stuck this material onto living flies, giving the bugs color-changing capabilities. This, Miyako said, could ultimately act as some kind of adaptive camouflage to protect pollinators from predators.

Real solutions?

But while improving the ability of other insects to pollinate flowers is a potential solution to falling bee numbers, Miyako said he was not convinced, and so began to look elsewhere. "It's very difficult using living organisms for real practical realizations, so I decided to change my approach and use robots," he said.

The hairs that make insects like bees fuzzy are important for their role as pollinators, because the hairs increase the surface area of the bees' bodies, giving pollen more material to stick to. In order to give the smooth, plastic drone similar capabilities, the scientists added a patch of horsehair to the robot's underside, which was then coated with the gel.

The researchers then flew the drones to collect pollen from the flowers of Japanese lilies and transport this pollen to other flowers. In each experiment, the researchers made 100 attempts at pollinating the flower, achieving an overall success rate of 37 percent. Drones without the patch of hair, or with uncoated hair, failed to pollinate the plants.

Miyako said there are currently limitations to the technology, because it is difficult to manually pilot the drone. However, he added that he thinks GPS and artificial intelligence could one day be used to automatically guide robotic pollinators.

Before these robo-bees become a reality, though, the cost of the drone will have to come down drastically and it's 3-minute battery life will need to improve significantly, Miyako said. But he added that he is confident this will happen eventually.

Dave Goulson, a professor at the University of Sussex in the United Kingdom, said he sees the intellectual interest in trying to create robot bees, but he's skeptical  about how practical they are and worries about distracting from more vital pollinator conservation work.Goulson specializes in the conservation of bumblebees but was not involved with the new research.

In a blog post, he wrote that there are roughly 3.2 trillion bees on the planet. Even if the robo-bees cost 1 cent per unit and lasted a year, which he said is a highly optimistic estimate, it would cost $32 billion a year to maintain the population and would litter the countryside with tiny robots.

"Real bees avoid all of these issues; they are self-replicating, self-powering and essentially carbon-neutral," Goulson wrote in the post. "We have wonderfully efficient pollinators already. Let's look after them, not plan for their demise." 

The 8 Most Famous Solar Eclipses in History

Blocking out the sun

Since ancient times, people have viewed the moon completely blacking out the sun for mere minutes — the entire solar eclipse, as the moon's shadow moves across Earth, can take hours — as omens that indicate an impending miracle, the wrath of God, or the doom of a ruling dynasty. 

From the earliest recorded eclipse, described on an ancient clay tablet, in Ugarit in modern-day Syria, to one that was linked to an uprising in an ancient Assyrian city, to a total solar eclipse that will surely go down in history when it dazzles the world in 2017, here are some of the most famous eclipses.

Antarctic Expedition Will Hunt for 'Missing' Meteorites

There are meteorites missing in Antarctica, and a group of British researchers plans to go find them.

The icy continent is a heaven for meteorite hunters, in part because flowing ice concentrates the space rocks in particular locations. But only about 0.7 percent of the meteorites found in Antarctica are iron-based, compared with 5.5 percent of the meteorites found around the rest of the globe.

"There's this huge underrepresentation of iron meteorites," said Geoffrey Evatt, an applied mathematician who specializes in ice-rock interactions at the University of Manchester in the United Kingdom. Evatt and his colleagues think they know where these metallic meteorites are, and they're now putting together a mission to bring modified land-mine-sweeping equipment to the middle of nowhere, Antarctica, to find them. 

Metallic meteorites

Around 90 percent of the meteorites that land on Earth are chondrites, which, according to the Armagh Planetarium, are nonmetallic, stony masses that cooled from droplets created when tiny planets smashed into each other in the early solar system. Iron meteorites, on the other hand, are metallic remnants of the cores of these small planets. Studying both kinds of meteorites can reveal information about the formation of the solar system.

Evatt and his colleagues aren't meteorite experts, and they had no idea that Antarctica's cache of space rocks was mysteriously low in iron-based samples. During a glaciology workshop in 2012, a "blue-sky" discussion about how rocks and ice interact led them to do some theorizing about meteorites, Evatt told Live Science.

Meteorites cluster in Antarctica because of the dynamics of the ice sheet: When a space rock falls on the continent, it gets covered with snow and becomes one with the ice. Often, the ice flows directly to the sea. But some Antarctic ice gets hung up on the Transantarctic Mountain Chain, crashing against the rock like a slow-motion wave. The upward motion of the ice brings buried meteorites to the surface, where wind and sun expose them by brushing away the top layer of snow and ice.

These spots are called meteor stranding zones, or blue-ice zones, and they make it easy for researchers to pluck space rocks right off the surface. But Evatt and his glaciologist and mathematician colleagues figured that iron meteorites, as they got close to the surface, might capture the sun's heat and transfer it to the ice around them, melting that ice and falling back downward. It's a bit like walking the wrong way on an escalator: The overall motion of the ice is up, but the meteorites never quite make it to the top.

Mission planning

After discussing the possibility of missing meteorites amongst themselves, Evatt and his colleagues got in touch with meteorite experts and planetary scientists and found out that their blue-sky theorizing was based on fact: Iron-based meteorites really are underrepresented in Antarctic collections.

Intrigued, Evatt and his colleagues tested their ice-melting-meteorite hypothesis in a laboratory setting with real meteorite samples embedded in chunks of ice and published their findings last year in the journal Nature Communications.

In December, the team received a grant from the Leverhulme Trust to put their hypothesis to the test in the field. The researchers will visit Antarctica in late 2018 into 2019 to survey for meteorite zones in previously unexplored areas of the Transantarctic Mountains. Most meteorite hunts have taken place on the side of the mountain chain that's near the U.S. McMurdo research station, on the Ross Sea side of the continent, Evatt said. The new mission will explore areas on the other end of the mountain chain, in the Shackleton, Pensacola and Argentina ranges, Evatt said. The region is within the purview of the British research station Halley VI, a base built on hydraulic legs so that it can be moved as the Brunt Ice Shelf upon which it sits crumbles.

The British Antarctic Survey is helping with logistics, Evatt said, which will include multiple leapfrogging flights to the mountain ranges to set fuel and supply depots. Meanwhile, University of Manchester researchers who normally specialize in land-mine clearance are working to modify their metal-detecting equipment to hunt for space rocks.

"Our meteorites are so sparsely spaced that we can't have any false negatives," said Evatt, meaning that the researchers don't want to miss any meteorites that are present.

The team will test its equipment on Arctic ice in Svalbard, Norway, in the spring of 2017, Evatt said. The goal of the late-2018 trip to Antarctica will largely be to survey for meteorite stranding zones on the surface, as well as to conduct further equipment testing. The real hunt for iron meteorites will start in late 2019 and early 2020, when the researchers will spend months camped far from any permanent base.

"It's going to be a bit wild, to say the least," Evatt said.