Japanese scientists have for the first time documented that lightning can spark nuclear reactions in the earth’s atmosphere, an event that happens via the release of antimatter.

Lightning is awesome — in the old-fashioned sense of ‘awesome,' as in that which inspires real awe. Lightning anywhere is a spectacular, incredibly powerful, burst of electricity that can set houses aflame, cause power widespread outages and generally terrify people, alongside its unshakeable pal, thunder. Little do we know, though, that lighting, by its nature, is a natural particle accelerator that can force electrons to move at near-light speed. Electrons, moving at such speeds collide with atoms in the atmosphere, which, in theory, causes a tiny nuclear reaction — a reaction that scientists have long speculated, even prior to the discovery of the neutron, according to The Conversation.

The theory existed, and after humanity went into space, satellites repeatedly registered x-rays and gamma-rays traveling up from Earth into outer space during violent thunderstorms. In 2015, however, a team of US and Japanese researchers unexpectedly stumbled upon lightning that pushed the gamma radiation flow downward, not upward. The particles were registered by several radiation detectors set up by the team near the Japanese town of Uchinada.

"The total fluence of gamma-rays at the ground was calculated to be approximately ~100,000 photons/cm2, much larger than the total combined fluence of all TGFs observed by satellites since 1994," the researchers later wrote. "This is one of the brightest gamma-ray flashes ever seen on the ground," said Joseph Dwyer, the author of the 2015 research, according to Gizmodo.

An amount of gamma energy that immense is assumed to do something nuclear by researchers. But no one has observed proof of atmospheric naturally-occurring nuclear reactions, particularly as scientists looked for the kind of rogue neutrons usually created during nuclear reactions, and found none.

On February 2017, however, a group led by Teruaki Enoto from Kyoto University in Japan observed a thunderstorm while hunting for radiation and anything nuclear. During their observations, they witnessed a flash which lasted less than one millisecond and caused a similar powerful flash of gamma radiation registered between 0.5 and 1.7 kilometers away, according to Enoto's study abstract, published in Nature.com. After that, the radiation level subsided sharply during a span of some 40 milliseconds, and remained extant — in what scientists describe as an "afterglow" — for some 30 seconds, which was long compared to previous findings.

Why would the radiation linger for such a long period? As Chemistry World explained, when atmospheric oxygen-16 and nitrogen-14 is hit by high-energy particles, unstable radioactive isotopes of these two gases form; gradually decaying into stable carbon-13 or nitrogen-15, and that decay is accompanied by an emission of positrons, the antimatter analog of electrons.

Yes, that antimatter, the one which annihilates in contact with normal matter. This mutual annihilation has a specific energy signature — of 0.511 megaelectronvolts — and that was precisely what the Japanese scientists registered.

"This line [on the graph] is a conclusive indication of electron-positron annihilation, and represents unequivocal evidence that photonuclear reactions can be triggered by thunderstorms," explained experimental physicist Leonid Babich from the Russian Federal Nuclear Centre, in a commentary on the research in Nature.

What this indicates is that the scientists have now discovered the second only known natural source of radioactive isotopes on Earth, the first being cosmic rays, discovered in 1912 by Austrian scientist Victor Hess.

But while it appears to now have been proven — that there is a working nuclear reactor up in our sky that spits antimatter from time to time — there is no need to panic. The amount of radiation humans receive is barely higher than your average dental x-ray, or so we are told. Besides, we as a species have lived within this atmospheric reactor for a very long time and appear to be multiplying speedily nonetheless.

"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," Enoto told Science Alert.

"This is not my highest concern if I ended up inside a thunderstorm," Dwyer says. "There are a half-dozen ways a thunderstorm can kill you if you're inside."