Astronaut captures amazing red sprite phenomenon from space

Yahoo

08-07-2025

Speeding around the Earth at 28,000 km/h, NASA astronaut Nichole Ayers captured an incredible view of a phenomenon known as a red sprite. Here's the science behind this 'transient luminous event'.
Lightning flashes through the air several million times every day, all around the world. The vast majority of those bolts occur inside clouds, between different clouds, or between the clouds and the ground. They happen as a result of large build-ups of negative or positive charge within clouds and along the ground, and act to balance out those charges.
A small fraction of these discharges — about one in every 1,600 on average — actually occur above the clouds. These 'transient luminous events' or TLEs happen when the charge build-up within a thunderstorm balances out between the cloud and the upper atmosphere, near the edge of space.
The different forms of transient luminous events. (NOAA)
On July 3, 2025, from her vantage point in the cupola of the International Space Station, astronaut Nichole Ayers was snapping pictures of thunderstorms as the station passed over Mexico and the United States.
In a spectacular feat of timing, one of her photographs managed to catch one of these TLEs, known as a red sprite, right in the middle of discharging!
This cropped view of the image snapped by astronaut Nichole Ayers zooms in on the red sprite she captured on July 3, 2025. (astro_ayers/X/NASA)
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Sprites are rapid flashes of red light that occur high up in the atmosphere, over 50 kilometres above the ground.
While they are referred to as upper atmospheric lightning, the only thing red sprites have in common with the typical form of lightning we see is the movement of electric charge from one part of the atmosphere to another. Other than that, they are very different phenomena.
Another sprite seen from the ISS on August 10, 2015, over Central America. (NASA)
Lightning only occurs in the lowest part of the atmosphere — the troposphere — and as it flashes through the air, it heats that air to temperatures hotter than the surface of the Sun. Sprites, on the other hand, only happen in the thin upper atmosphere — the mesosphere and ionosphere — and they are a cold plasma phenomenon. Their glow probably has more in common with that of a fluorescent light bulb, or the Aurora Borealis.
The colour of a sprite comes from the fact that our atmosphere is mostly nitrogen. When an air molecule becomes energized, one of the electrons orbiting around it will jump up to a higher level. To return to its 'ground state', where the electron drops back down into its normal orbit, it emits a flash of light to dump its excess energy. In the case of nitrogen, the light emitted has a very strong red component, along with a bit of blue and purple.
This immense 'jellyfish sprite' was captured over a storm in West Texas on July 2, 2020. (Stephen Hummel)
It seems that we've known about sprites, or at least transient luminous events in general, for around 300 years. According to NASA, pilots apparently were reporting sightings of them since the first military and commercial flights in the early part of the 20th century. It wasn't until 1989, though, that they were finally caught on camera.
While we know what sprites are, explaining how they form is a bit more challenging. However, here's what we know, as well as what researchers speculate, about the process.
The formation of a sprite starts inside a thunderstorm. There, the exchange of electrons between colliding ice crystals and snow pellets produces distinct regions of electric charge within the cloud. Weak positive charge collects at the base, strong negative charge accumulates in the middle, and strong positive charge builds at the top.
Most often, lightning will balance the negative charge at the core of the cloud by linking it with a region of positive charge on the ground, inside another nearby cloud, or even within the same cloud. This is the common negative lightning that occurs millions of times per day.
The likely distribution of electric charge of a cumulonimbus cloud has been drawn onto this User-generated Content image of a storm taken on Aug 27, 2022, from Carrot River, SK, and uploaded to the Weather Network's UGC gallery. (Fran Bryson/UGC)
Occasionally, though, the strong positive charge accumulated at the top of the thunderstorm cloud has a chance to discharge, by linking with a region of negative charge along the ground. When this happens, we see a powerful stroke of positive lightning.
This appears to be the point where a sprite has a chance to form.
Normally, as a thunderstorm cloud is rolling along through the troposphere, at the same time, the air much higher up has a strong positive charge due to interactions with particles streaming into the atmosphere from space.
Usually, this upper atmospheric positive charge doesn't have anywhere to go. It needs a region of negative charge to balance out. The negatively charged core of the thunderstorm could do this. However, the positive charge accumulated at the top of the cloud stands in the way.
When a positive lightning strike lances out between the top of the cloud and the ground, though, much of that excess positive charge is stripped away. At that moment, the negative charge in the middle of the cloud becomes directly exposed to the positively charged mesosphere, allowing a connection to form.
Based on observations, sprites are almost always preceded by a positive lightning strike. Thus, they are a potential trigger for the phenomenon. Even so, a positive lightning strike doesn't always guarantee that a sprite will appear. Thus, it's likely that some other component needs to be present for the sprite to form.
That other component could be gravity waves.
The video above was recorded from atop Mount Locke in West Texas, in May 2020, by Stephen Hummel, the dark sky specialist at the McDonald Observatory. In the video, gravity waves can clearly be seen, illuminated by a phenomenon called airglow, radiating away from a storm along the horizon to the lower right. Amid the gravity waves streaming through the field of view, several sprites are also captured (watch closely at 1s, 3s, 7s and 12s into the video).
Gravity waves behave like ripples on the surface of a pond, with air rising and falling as it tries to balance out the forces of gravity and buoyancy. When a powerful thunderstorm's strong updraft winds reach the top of the troposphere, they are deflected by the stable air of the lower stratosphere, and are forced to spread outward instead.
Research has already shown that the action of gravity waves can have an impact on the upper atmosphere. This could be another way they influence what happens, far above the surface.
Now, exactly how gravity waves might play a role in sprite formation isn't yet known. Some researchers have noted that sprites appear to form at what they call "plasma irregularities" in the ionosphere. However, these irregularities are themselves, also a mystery. It could be that gravity waves play a role in forming these irregularities. For now, though, no one knows. To understand this phenomenon better, more sightings, more captures, and more research are required.
Click here to view the video