Certain Kinds of Lightning Produce Nuclear Reactions in Thunderclouds

This usually occurs inside the hottest places in the universe, such as in the heart of a supernova.

If you’ve ever been shaken by a thunderclap, or sat in spectacle as a white forked tongue streaked across the sky, you’ve bore witness to one of the most powerful phenomena in the universe. Researchers in Japan recently found out just how powerful lighting is. Certain kinds produce gamma rays, leading to a nuclear reaction. According to the report published in the journal Nature, “Thunderclouds are natural particle accelerators.”  


Gamma rays have the smallest wavelength on the electromagnetic spectrum. They also pack the most energy. They’re usually born within the hottest environments, such as in the hearts of pulsars, neutron stars, and supernovas. Knowing this, it’s mind-blowing that gamma waves can be created right here on Earth, by a relatively common phenomenon.

Nuclear reactions within lightning storms was first hypothesized nearly a century ago. In the 1980s and sporadically up until today, detection has been made via land-based observatories, aircraft, and satellites. And there was also a curious case in 2015, of a Japanese beach town where--after a series of high-energy thunderstorms, gamma rays were recorded penetrating the ground. Despite all this, scientists were unable, until now, to confirm exactly what particles were being made during these photonuclear reactions.

Credit: Getty Images.

The latest study is the first time this phenomenon has been observed directly, and one of the first times radioactive isotopes were seen naturally occurring in the environment. The other place such isotopes are made is when cosmic rays bounce off the atmosphere. Within thunderheads, gamma rays knock free the neutrons of nitrogen atoms, setting off a nuclear reaction. Storms are likely on the Sea of Japan’s coast in winter. Scientists took advantage of this last February, by commandeering four reaction detectors at the nearby Kashiwazaki-Kariwa nuclear power station, located in the coastal city of Niigata.

Two lighting strikes were recorded producing radiation. Researchers gathered data and analyzed it. The strikes occurred about one-third of a mile away (0.5-1.7 km). The energy of these strikes was 0.511 megaelectronvolts (MeV). The photonuclear reaction lasted for up to a minute. What resulted was the kind of electron–positron annihilation indicative of a nuclear reaction. Neutrons and positrons were the final result.

Teruaki Enoto is an astrophysicist from Kyoto University and a researcher on this study. He told Science Alert, "The photonuclear reactions indicate that lightning also interacts even with nuclei if gamma rays have sufficiently high energy to knock out neutrons from the nuclei." So lighting storms can cause radiation, is this a cause for concern? According to Enoto, "Since the radioactive isotopes are short-lived, spatially restricted, and [comprise a] relatively small amount compared to usual background radiative environments, I think there is no health risk from this phenomena.”

Scientists may have found a heretofore undiscovered avenue in which rare isotopes are created on our planet. They still don’t know if this happens during all lightning storms or only the most powerful ones. Future studies will likely unravel that mystery, along with what other (if any) isotopes or particles are born inside of a raging storm cloud.

To learn more about the science behind lightning, click here:

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New fossils suggest human ancestors evolved in Europe, not Africa

Experts argue the jaws of an ancient European ape reveal a key human ancestor.

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  • The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
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Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.

A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.

Rethinking humanity's origin story

The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)

As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.

David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.

The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.

Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"

He recently outlined this idea at a conference of the American Association of Physical Anthropologists.

It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.

"Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."

Migrating out of Africa

In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.

Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.

The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.

The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.

Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.

Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.

Did we head east or south of Eden?

Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.

Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.