You have likely seen lightning flash from a storm cloud to strike the ground. Such bolts represent only a small part of the overall phenomenon of lightning, though. The most powerful activity occurs high above the surface, in Earth's upper atmosphere.

Up there, lightning creates brief bursts of gamma rays that are the most high-energy naturally produced phenomena on the planet. Researchers recently measured these high-energy terrestrial gamma-ray flashes, or TGFs, using instruments on the International Space Station. The work helps reveal the mechanism behind the creation of the bright flashes we call lightning.

The instruments are part of the Atmosphere-Space Interactions Monitor (ASIM), an Earth observation facility on the outside of the space station used to study severe thunderstorms and their role in Earth's atmosphere and climate. ASIM recorded other types of upper-atmospheric lightning known as transient luminous events (TLEs) in addition to TGFs. ASIM's high-speed instruments helped researchers to determine the sequence of events that produces TGFs, as reported in a paper recently published in the journal Science.

"With ASIM, we see how the atmosphere and clouds bubble like a pot of stew on the stove," says Torsten Neubert of the National Space Institute, Technical University of Denmark and lead author on the paper. "Convection brings humidity, dust and other particles into the upper atmosphere where they affect Earth's radiation balance. Lightning is a measure of convection and can be relatively simple to put into weather and climate models."

Scientists have successfully transplanted functional miniature livers into rats, after growing the bioengineered organs in the lab from reprogrammed human skin cells.

The experiment, which gave the animals working liver organs, could lay the groundwork for future treatments to address terminal liver failure - a disease that claims the lives of over 40,000 people in the US every year.

While there's still a lot of work to be done before the technique can directly aid human patients, the researchers say their proof of concept may help underpin a future alternative to liver transplants, which are often incredibly expensive procedures to perform, in addition to being strictly limited by donor supply.

A study by the Netherlands' National Institute for Health (RIVM) published on Wednesday concluded that children under the age of 12 play little role in transmitting the new coronavirus.

The study in the country's leading medical journal Nederlands Tijdschrift Voor Geneeskunde followed the progress of the disease in 54 families, including 227 people in all.

Studies in other countries have previously found that children are less often infected by the virus and, once infected, less often become seriously ill.

"Yes, children can become infected, but transmission takes place primarily between adults of similar age, and from adults to children," the study said in its conclusion.

CBET 4790 & MPEC 2020-L09, issued on 2020, June 02, announce the discovery of a comet (magnitude ~20) in four 45-s w-band CCD images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala. The new comet has been designated C/2020 K7 (PANSTARRS).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 8 unfiltered exposures, 180 seconds each, obtained remotely on 2020, June 02.2 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 6" in diameter and a tail 3" long in PA 306 (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini).

Our confirmation image (click here for a bigger version)

For a long time after their discovery in 1877, scientists assumed Mars' two puny moons — Deimos and Phobos — were captured asteroids. This belief persisted until evidence revealed both moons formed at the same time as the Red Planet itself, and that the smaller one, Deimos, has a mysteriously tilted orbit. However, it wasn't until 2017 that researchers put forth a new idea that could explain why Deimos' orbit is slanted by 2 degrees.

"The fact that Deimos' orbit is not exactly in plane with Mars' equator was considered unimportant," said SETI Institute research scientist and lead author Matija Ćuk in a press release. "But once we had a big new idea and we looked at it with new eyes, Deimos' orbital tilt revealed a big secret."

Octopuses, squids and other sea creatures can perform a disappearing act by using specialized tissues in their bodies to manipulate the transmission and reflection of light, and now researchers at the University of California, Irvine have engineered human cells to have similar transparent abilities.

In a paper published today in Nature Communications, the scientists described how they drew inspiration from cephalopod skin to endow mammalian cells with tunable transparency and light-scattering characteristics.

"For millennia, people have been fascinated by transparency and invisibility, which have inspired philosophical speculation, works of science fiction, and much academic research," said lead author Atrouli Chatterjee, a UCI doctoral student in chemical & biomolecular engineering. "Our project — which is decidedly in the realm of science — centers on designing and engineering cellular systems and tissues with controllable properties for transmitting, reflecting and absorbing light."

The Universe is not a structureless mish-mash of space stuff, but there's still a lot we don't know about how it's put together.

Although we know that everything is connected by a vast, filamentary web, we tend to operate under the assumption that the distribution of galaxies among those filaments is somewhat random.

In other words, if you pick a patch of sky, scientists generally think that the spin directions of all the galaxies in that patch will be more or less evenly distributed.

Well, it turns out that that assumption may be incorrect.

There's something sobering - terrifying is the more apt word - about a peer-reviewed paper that contains, under the heading "Significance", these words:

"The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilisation, because it is irreversible.

Thousands of populations of critically endangered vertebrate animal species have been lost in a century, indicating that the sixth mass extinction is human caused and accelerating. The acceleration of the extinction crisis is certain because of the still fast growth in human numbers and consumption rates.

In addition, species are links in ecosystems, and, as they fall out, the species they interact with are likely to go also. In the regions where disappearing species are concentrated, regional biodiversity collapses are likely occurring. Our results re-emphasise the extreme urgency of taking massive global actions to save humanity's crucial life-support systems."

The research article this statement precedes - just published in Proceedings Of The National Academy Of Sciences - is titled "Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction". Biological annihilation - the authors' words.

More than 500 terrestrial vertebrate species, the study says, are on the brink of extinction. They include icons such as the Sumatran rhino (Dicerorhinus sumatrensis) and Española Giant Tortoise (Chelonoidis hoodensis) and their decline is likely driven in large part by human activities in biodiversity hotspots.

Ever since astronauts attached the 7.5 tonne AMS detector to the International Space Station in May 2011, the space-based magnetic spectrometer, which was assembled at CERN, has collected data on more than 150 billion cosmic rays - charged particles that travel through space with energies up to trillions of electron volts. It's an impressive amount of data, which has provided a wealth of information about these cosmic particles, but remarkably, as the spokesperson of the AMS team Sam Ting has previously noted, none of the AMS results were predicted. In a paper just published in Physical Review Letters, the AMS team reports measurements of heavy primary cosmic rays that, again, are unexpected.

Primary cosmic rays are produced in supernovae explosions in our galaxy, the Milky Way, and beyond. The most common are nuclei of hydrogen, that is, protons, but they can also take other forms, such as heavier nuclei and electrons or their antimatter counterparts. AMS and other experiments have previously measured the number, or more precisely the so-called flux, of several of these types of cosmic rays and how the flux varies with particle energy and rigidity - a measure of a charged particle's momentum in a magnetic field. But until now there have been no measurements of how the fluxes of the heavy nuclei of neon, magnesium and silicon change with rigidity. Such measurements would help shed new light on the exact nature of primary cosmic rays and how they journey through space.

In its latest paper, the AMS team describes flux measurements of these three cosmic nuclei in the rigidity range from 2.15 GV to 3.0 TV. These measurements are based on 1.8 million neon nuclei, 2.2 million magnesium nuclei and 1.6 million silicon nuclei, collected by AMS during its first 7 years of operation (19 May 2011 to 26 May 2018). The neon, magnesium and silicon fluxes display unexpectedly identical rigidity dependence above 86.5 GV, including an also unexpected deviation above 200 GV from the single-power-law dependence predicted by the conventional theory of cosmic-ray origin and propagation. What's more, the observed rigidity dependence is surprisingly different from that of the lighter primary helium, carbon and oxygen cosmic rays, which has been previously measured by AMS.

Colorado State University Distinguished Professor Sonia Kreidenweis and her research group identified an atmospheric region unchanged by human-related activities in the first study to measure bioaerosol composition of the Southern Ocean south of 40 degrees south latitude.

Kreidenweis' group, based in the Department of Atmospheric Science, found the boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine — free from particles, called aerosols, produced by anthropogenic activities or transported from distant lands. Their findings are published in Proceedings of the National Academy of Sciences.

Weather and climate are complex processes connecting each part of the world to every other region, and with climate changing rapidly as a result of human activity, it's difficult to find any area or process on Earth untouched by people. Kreidenweis and her team suspected the air directly over the remote Southern Ocean that encircles Antarctica would be least affected by humans and dust from continents. They set out to discover what was in the air and where it came from.