Hunting ghosts in the sky and finding what makes their colors

In June 2019, scientists in Spain went searching for ghosts haunting the skies over the Mediterranean. These green wisps, dancing above pink-red lightning, at extremely high altitudes during thunderstorms, were only discovered in May of that year. What were they? The only way to find out is to pick one up.

But this would be an annoying task. These ghosts are aptly named: they are difficult to see with the naked eye and appear with just a heartbeat dozens of miles above the Earth’s surface.

“Seeing a ghost is really difficult,” he said. Maria Passas Faroresearcher at the Institute of Astrophysics in Andalusia, Spain.

But on September 21, 2019, they were finally able to capture one using a specialized camera: a green spirit flashing at the crown of a jellyfish-shaped fuchsia lightning swirl 50 miles above sea level. After disentangling the different wavelengths of light emitted by the ghost, scientists revealed its elemental composition.

In a study published on Tuesday in the journal Nature CommunicationsDr. Passas-Faro and her colleagues revealed that the ghost’s pale emerald skin came in part from excited oxygen, similar to the green glow of the aurora borealis; Nitrogen also plays a role.

But the main contributor was another element: iron. This was a surprise because the metal was eventually delivered from space.

A better understanding of ghosts and other ephemeral, lightning-like entities could help scientists explain the hard-to-resolve chemistry and physics of Earth’s upper atmosphere.

“There are layers of metal dancing” inside and above thunderstorms, Dr. Passas-Faro said.

Ghosts are a type of transient luminous event, or TLE, that has been It was first described by scientists in 1989. Can include TLEs Blue planes shooting Rising from thunderstorm clouds, as well as vermilion-colored upper-air lightning that can come in many forms, such as carrots and jellyfish, and is known as ghost.

Temporal lobe epilepsy “is like fireworks,” Dr. Passas-Faro said. Little is known about them, especially the ghosts, the first of which was seen above a ghostly storm over Oklahoma in May 2019.

To capture their ghost, her team pointed a spectroscopic camera — which can use light to confirm chemistry — into the upper atmosphere from an observing site in Castellgalli, Spain. All they can do is wait for the goblins’ thunderstorms to appear, crossing their fingers and hoping that at least one ghost will briefly be adorned with a ghost, and have their camera pointed at the right place.

Eventually, they found one flapping on a jellyfish creature.

“It was a matter of luck,” Dr. Passas-Faro said.

This engine was powered largely by extraterrestrial iron, not atmospheric oxygen. The camera also revealed the presence of nickel, sodium and silicon. The complex chemical soup responsible for this ghost even added a yellow-orange tinge to its green glow.

All of these elements often come from micrometeorites and deep-space dust particles that sink almost continuously into the upper atmosphere. This means that ghosts can effectively be viewed as interplanetary visitors.

However, some researchers said too many conclusions should not be drawn from the new study’s findings.

“The mineral relics are interesting, but I would caution that this was just one event,” he said. Chris Vagaski, a researcher at the University of Wisconsin-Madison, was not involved in the new work. To find out if all the ghosts are iron-powered ghosts, he added, “it would be nice to see results from multiple ghosts.”

He has no doubt that the hunt for ghosts, and other TLEs, will continue—largely because these ghosts are inherently deceptive.

“It’s really incredible to think that there’s a lot more going on during a thunderstorm than you can see or hear,” Dr. Vagaski said.