Miles Hatfield: Hello everyone and Happy Halloween. Today, for our Halloween special,
A NASA scientist finally goes on record about the truth behind sprites, gnomes, pixies, ELVEs, trolls, and more.
Of course, we're not talking about the mythical creatures of the forest...
We're talking about the colorful lights that sometimes appear high in our upper atmosphere above thunderstorms --
more commonly known in scientific parlance as transient luminous events.
I'm Miles Hatfield, NASA science communicator,
and I'm here with Burcu Kosar, NASA scientist and expert on these mysterious
electrical phenomena. Burcu is starting a brand new project called Spritacular that aims to open
up this exciting field of science to broad public participation. We're here to talk about that
project, and the ghostly figures that it studies. So first off, what are sprites and some of these
other things that I mentioned at the top?
Dr. Burcu Kosar: Yeah, um, so sprites, also known as red sprites, due to their dominant red color
are upper atmospheric electrical discharges of air that are connected to thunderstorm systems below.
So what I mean by that is every sprite event in a way has a parent lightning flash. So they're
tightly connected in a way, they happen at about 50 miles up in our atmosphere. And they have
complex morphological features. What I mean by that is, they come in various shapes and sizes,
some of them look like a carrot bunch just pulled out of the ground. Some of them look like columns,
some of them look like angels, and the most fascinating one is actually called "dancing
sprites," they almost flicker like a little light show about the thunderstorm systems. And And also,
we do not really currently understand how they take the shape they do or why they take the shape
they do. It is a very least understood field of research.
Miles Hatfield: How big are we talking? How rare are they? How hot or cold? Are they keeping up
more sense of what sprites are like? So
Dr. Burcu Kosar: what I would say is they are not like the hot lightning bolts, they are relatively
cold. They actually their home is the coldest layer of the atmosphere, which is the upper
sections of the mesosphere, so they are, they're formed by these filamentary plasma channels called
"streamers," they are weakly ionized channels, so they're cooler in comparison to the lightning bolt
itself. They are, they're relatively rare to be able to make them happen, we need very powerful,
positive cloud-to-ground lightning flashes. So what are these positive cloud to ground lightning
flashes? They are very powerful flashes, they they transfer the positive charge from the cloud to the
ground, and they are responsible for generation of sprites.
Miles Hatfield: So why have I not heard of sprites before? Are they very rare? Why? Why don't most
people know about these?
Dr. Burcu Kosar: So I would say it's a relatively new field of research. This field of research
started in 1990s, when a group of scientists were testing a low light level TV camera for an
upcoming rocket mission. And there must have been a thunderstorm relatively nearby. And they captured
sprites on the record for the first time. When they reviewed their footage, they saw these two
massive luminous blobs extending above the active thunderstorm systems. And that is
actually the first milestone image that kickstarted this field of research in atmospheric and
space electricity. After that, there has been many campaigns started to catch them and study them.
There were ground-based campaigns, there were aircraft campaigns, the reason an aircraft's
altitude is very, very good to study or look at these phenomena is the vantage point. When you're
flying around the nearby thunderstorms, you have this great view of the top of the thunderstorms,
which is home for these phenomena that we refer to as "transient luminous events." So another important
thing to mention here is this field of research is actually no stranger to citizen science. Because
when you look at some of the historical anecdotes, people have been describing sightings of these
strange flashes of light above the thunderstorm, almost going back to hundreds of
years, even pilots were seeing them but what they see is actually just a flicker of light, they do
not see these phenomenal detail images that are shared on the on the internet. So that is a still capture
capture ripped off of video footage. So they're very, very fast. So to the human eye,
they're almost like a flicker of liight, like a flash of light. And it is very hard to perceive
color. So people when they look at the aurora, they see these green arcs moving in the sky. For
sprites, unfortunately, that is not possible because they are very brief. And very fast. They
are they're visually beautiful in the still photographs.
Miles Hatfield: So it sounds like you've seen some sprites in person before. Can you tell me what
that was like?
Dr. Burcu Kosar: So I wouldn't say I have seen it. I have captured it on camera about a year ago, I
have been studying sprites for about 15 years now. I did my research work during my PhD. And like I
said, it was it was an opportunity. We recorded a sprite-chasing documentary down in Oklahoma, I had
the opportunity to work with one of the phenomenal sprite-chasers Paul Smith. And we went and we
chased bunch of storms that was over, over a nearby state. And we were lucky enough to capture
a sprite on camera and it was actually column sprites. It was it was a great experience, I would
say because that kind of in a way made me realize how knowledgeable citizen scientists are. And the
amount of information that we can exchange and collaborate and advance this field of research
was really, really great. And, and that's why I'm thinking this project of mine that is going to be
launching this month is definitely a very worthwhile effort. And I'm so excited about it.
Miles Hatfield: Good. Tell, tell me more about what Spritacular is. You mentioned citizen
science. But what does that mean? And how can your average person get involved in something like
this?
Dr. Burcu Kosar: Yeah, so Spritacular is NASA's brand new citizen science project. So citizen science
projects are in a way, a collaboration between professional scientists and members of the public.
So it is almost like an exchange of information. So as a scientist, I look at a lot of scientific
data, I study the physics of this phenomenon. And scientists are very knowledgeable about these. And
we look at satellite data. But when you look at the public and sprite chasers, they are phenomenal
photographers. And not only that, they're very knowledgeable about what they're doing. They're
almost I would, it would be wrong to call them amateurs, they're extremely talented. So they
capture these phenomena. And they want to learn more about what they're capturing and what these
things are. So that's where this project will come in. We want to create a bridge between these two
communities, and enable exchange of information for the advancement of science collaboratively
together. So the way people can participate in this project is, I would say if you live in a
place where thunderstorms frequently happen, and if you happen to own a DSLR camera. And if you're
a little bit patient, and if you like to go outside at night and watch the night sky, this is
actually an excellent project for you. I would say the hardest part of catching a sprite is knowing
where to look. But there will be wealth of information on our website, spritacular.org,
where you can come and learn about these phenomena. And if you happen to observe sprites or
any other TLEs, you can submit your observations to our database which will be used by the
scientific community for research in the future. So if you -- long story short -- if you are passionate
about thunderstorms, if you have some patience and an off-the-shelf DSLR camera, you're off to a great
start to capture these events.
Miles Hatfield: This raises a good question. I mean, probably most people who know about NASA,
know that we've got all kinds of satellites, we've got all kinds of equipment that we use to make
observations of the night sky. What makes a person with a camera on the ground so useful for these
sorts of questions that you're asking?
Dr. Burcu Kosar: So, yeah, so because these events occur in a specific region of the atmosphere as I
mentioned earlier, the best vantage point to observe them are from aircrafts or locations where
storms happen frequently from the orbit satellites see them but it's very hard to resolve the details
of these phenomena. The ground observations give us an excellent vantage point to see the details
and also, they serve as ground truth for satellite observations, if you look at the
satellite data to understand what we captured, and if we have a confirmation from the ground, that is
an excellent source of data point, I would say, and with this project, we are going to be creating
the first ever crowdsourced database of TLEs, which currently doesn't exist. So it is a very exciting
endeavor, it will be open to every scientific community. And we intend to make this a global
project because where powerful thunderstorms happen, you'll have a chance to see sprites and
other TLEs.
Miles Hatfield: So tell me more. What about these other TLEs? Obviously, your your project is
called Spritacular, as I understand sprites are the most common TLE that people are likely to see,
but there's a range of others. Can you say more about what they are?
Dr. Burcu Kosar: Yeah, of course. So the "transient luminous events" is the technical name the science community
gave to refer to these optical emissions above the thunderstorms. So this region is almost literally
like an electrical zoo, we have all sorts of different phenomena. Sprites are one of the like
you mentioned one of the most commonly observed types, but we have halos, we have ELVEs, halos are
almost like a diffuse glow, like in the shape of a pancake. ELVEs are in the shape of a doughnut that
extends radially outward. And we have jets and gigantic jets which shoot up from the
thunderstorm tops, gigantic jets are so massive, they literally create an electrical bridge between
the thunderstorm tops and the ionosphere, effectively coupling two different regions of the
atmosphere. So these are some other types of TLEs that we are interested in, including in our
database for scientific research.
Miles Hatfield: Where do they get these funny names from?
Dr. Burcu Kosar: Yeah, that's a good question. So the first discovered TLE was sprites, and because
of their elusive fleeting nature, they were dubbed as sprites by late Dave Sentman. And after that,
it kind of got stuck. And when the field of research got kicked off with this first
observation, we started discovering more types. And I think the overall theme sort of got stuck.
Some of these names are actually acronyms, but I think scientific field has been a little bit
playful with naming these optical phenomena.
Miles Hatfield: So aside from making bright light shows, and quick, you know, momentary flashes, to
these TLEs have any effect on people on our Earth system as a whole? Are they dangerous in any way?
Dr. Burcu Kosar: Yeah, that is a good question. So they happen as I mentioned earlier, at about 50
miles up in our atmosphere, so they do not endanger us here on Earth. But of course, they
have effect on other Earth systems, such as the global electric circuit. So "global electric
circuit" is the name that we give collectively to circulating currents in our atmosphere. So sprites
and other TLEs being electrical phenomena, they do carry currents. So they provide in a way, feedback
into this global electric circuit. I would say a thunderstorm and lightning flash or sprite or any
other TLE is not an isolated event, it actually feeds back into this larger system that we call
global electric circuit. And another another thing to mention here, sprites locally affect the
atmosphere electrically and chemically and modify its contents. So what this does is this affects
our long-range radio communication systems, and also the atmospheric chemistry changes that they
do locally in the atmosphere. It feeds back into the atmospheric chemistry. So they do have
global effects that we would like to study and understand further.
Miles Hatfield: This stuff is fascinating. Thank you so much for joining me for this discussion.
Burcu. Thank you, everyone. And before you all head out for trick or treating, there's much more
to learn about transient luminous events. Burcu will be sticking around and answering your
questions today, so leave them in the comments below.
Thank you all for joining us and Happy Halloween!