The aurora borealis, a mesmerizing curtain of green, red, and purple, has long captivated night sky watchers. Lately, however, a strange aurora-like phenomenon has emerged: the mauve and white stripes known as “steves,” and the phenomenon that often accompanies them. shining green “Picket Fence” – intrigues both scientists and sky watchers.
First identified in 2018 as distinct from the more familiar aurora borealis named Steve, named after a character in the 2006 children’s film, the picket fence phenomenon was initially linked to the same physical process as the aurora borealis. It was thought to be a product of. However, this assumption left many questions regarding its unique origins unanswered. shining luminescence.
New mechanism to generate sky glow
Claire Gasque is a promising graduate student in physics. University of California, Berkeley. Gask proposed an interesting explanation for these phenomena, suggesting a physical mechanism that is very different from the traditional causes of auroras.
“In some cases, this could upend our models of what produces the light and energy of auroras,” Gaske says. “This is really amazing. He’s one of the biggest mysteries in astrophysics right now.”
Collaboration with the Institute of Space and Astronautical Science (SSL) At Berkeley, Gask was NASA A mission to launch a rocket into the Northern Lights to test her hypothesis. The study coincides with the sun entering a more active phase of her 11-year cycle, making it the perfect time to study unusual phenomena like staves and picket fences.
Distinguishing between “Steve” and the common aurora
Gask’s research focuses on the peculiar behavior of electric fields in the upper atmosphere. She suggests that these fields, parallel to Earth’s magnetic field, may produce the spectrum of colors observed in the picket fence phenomenon.
This hypothesis challenges existing models of auroral light and energy production and has important implications for understanding the interaction between Earth’s magnetosphere and ionosphere.
Common auroras are caused when solar winds energize particles in Earth’s magnetosphere, causing oxygen and nitrogen molecules in the upper atmosphere to emit light at specific frequencies.
But Steve lacks the blue light typical of the most energetic particle interactions in auroras, instead exhibiting a wide range of frequencies centered around violet or mauve colors. Interestingly, Steve and Picket Fences occur at lower latitudes than regular auroras and can even occur near the equator.
A parallel electric field is working
Gask’s research hypothesizes that the radiation from the “picket fence” is generated by a low-altitude electric field parallel to the Earth’s magnetic field. Using a widely accepted physical model of the ionosphere, she demonstrated that at an altitude of about 110 km a parallel electric field of about 100 millivolts per meter could accelerate electrons.
This acceleration is sufficient to energize the oxygen and nitrogen atoms, resulting in spectrum of light Observed in ‘Picket Fence’ and ‘Steve’ aurora. She also identified unique conditions in the region, including a decrease in plasma density and an increase in the presence of neutral oxygen and nitrogen atoms. These act as insulators and can prevent short circuits in the electric field.
“If you look at the picket fence spectrum, you’ll see that there’s a lot more green than you expected. And there’s no blue at all that comes from the ionization of nitrogen,” Gaske said. “What this tells us is that the electrons that can produce that color are only in a certain energy range, and those particles have too much energy to make it all the way into the atmosphere from beyond space. about it.”
Instead, she said, “The light from the picket fence is produced by particles that need to be energized right there in space by parallel electric fields, which we have been studying or It’s a completely different mechanism than any aurora we know of before. “
Find Steve with Rocket
brian hardingGaske, an assistant research physicist at SSL and co-author of Gaske’s paper, emphasized the importance of this discovery.
“What’s really interesting about Claire’s paper is that we’ve known for several years that Steve’s spectrum tells us that there’s some very strange physics going on. I had no idea what it was,” Brian said. “Clare’s paper showed that parallel electric fields can explain this strange spectrum.”
To test their hypothesis, the researchers propose launching a rocket from Alaska to measure the electric and magnetic fields within these phenomena. This initiative is part of NASA’s Low-Cost Space Access (LCAS) program and are expected to deepen their understanding of the chemistry and physics of the upper atmosphere. The initial target is what is known as an enhanced aurora, which is a regular aurora with “Steve” and “picket fence” luminescence embedded in it.
“The enhanced aurora is basically a bright layer embedded in the normal aurora. The color is similar to a picket fence in that it has less blue and more green from oxygen and red from nitrogen. The hypothesis is: “These are also generated by parallel electric fields, but they are much more common than picket fences,” Gasque said.
The plan is to “fly a rocket through the enhanced layer and actually measure parallel electric fields for the first time,” as well as “a second to measure particles at higher altitudes to distinguish between states.” She said she also plans to “launch a rocket.” From what causes the aurora borealis. ” Ultimately, she wants the rocket to pass directly through “Steve” and the “picket fence.”
Curiosity drives Steve’s aurora research
Gasque attributes her success to collaborations with experts who study different atmospheric layers, including the mesosphere and stratosphere. This interdisciplinary approach has led to significant advances in our understanding of the differences between Aurora and Steve.
Harding, Gasquet, and their colleagues hope to submit a proposal for a sounding rocket campaign to NASA this fall and receive a response on its selection in early 2024. Gask and Harding consider this experiment an important step toward understanding the chemistry and physics of the universe. Upper atmosphere, ionosphere, and Earth’s magnetosphere.
“How those electric fields got there, what kind of waves they are or are not related to, and how that affects the larger energy transfer between Earth’s atmosphere and space. “It’s safe to say there will be a lot of research in the future about what that means,” Harding said. “We really don’t know. Claire’s paper is the first step in that chain of understanding.”
The team is looking forward to NASA’s decision on the rocket program, expected in the first half of 2024.
In summary, the research led by Claire Gasque represents a vital advance in astrophysics. Gask revealed the elusive nature of “Steve” and what “Picket Fence” is not Aurora. As the solar cycle progresses, these discoveries promise not only to unravel the mysteries of these phenomena, but also to foster a broader understanding of the dynamic interactions between Earth and the universe.
Learn more about Aurora
The Northern Lights, commonly known as the Northern Lights and Southern Lights, appear as a mesmerizing natural light show in the Earth’s polar skies. They are caused by an interesting interaction between Earth’s atmosphere and the solar wind.
As detailed above, scientists believed that the “Steve” and “Picket Fence” phenomena resulted from the same physical process as the aurora borealis. However, this idea left many questions unanswered about the origin of that unique glowing luminescence.
Origin: Solar Connection
A powerhouse of energy and particles, the sun constantly emits a stream of charged particles, the solar wind. These particles encounter Earth’s magnetic field on their way to Earth and play a key role in the formation of auroras.
When the solar wind reaches the Earth, it is influenced by the magnetic field. Earth’s magnetic field, which extends into space, acts as a shield and directs these particles towards the poles. Here, magnetic field lines concentrate these charged particles into Earth’s upper atmosphere.
“Steve” and the science of the aurora
The core phenomenon of auroras occurs when these charged particles, primarily electrons, collide with gases such as oxygen and nitrogen in Earth’s atmosphere. This collision transfers energy to the gas molecules, which excite them and emit light. This is the essence of an aurora display.
The specific colors of the aurora and Steve vary from green and red to blue and violet, depending on the type of gas involved and the altitude of these interactions.
Solar activity has a significant impact on the intensity and frequency of auroras. During solar maxima, increased solar flares and coronal mass ejections produce more powerful and frequent auroras. Conversely, solar minimum leads to a decrease in auroral activity.
Cultural and historical significance
Beyond their visual splendor, the aurora provides valuable insight into the dynamics of Earth’s magnetosphere and its interaction with solar radiation. Studying the aurora helps us understand how Earth’s magnetic field protects us from harmful solar radiation.
The Northern Lights hold a special place in various cultures and have inspired myths and folklore. From being seen as the Valkyrie’s shield in Norse mythology to representing ancestral spirits in indigenous beliefs, the Northern Lights have been a source of wonder and inspiration throughout history.
In summary, the breathtaking aurora borealis is more than just a visual spectacle. They are the dynamic interaction of the solar wind and Earth’s magnetic field, providing insight into Earth’s protective shield and continuing to fascinate people across cultures and generations.
The full study will be published in a journal Geophysical Research Letters.
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