The mysterious aurora-like phenomenon called "STEVE" has gotten even more strange to scientists.

If you don't know the meaning of "STEVE", it is an acronym for Strong Thermal Emission Velocity Enhancement, meaning "Strong Thermal Emission Velocity Enhancement".

And unlike the common southern and northern lights, which blanket the sky with green swirls near Earth's magnetic poles, Steve appears as a band of white and purple light that dips diagonally toward the horizon, extending hundreds of miles through the atmosphere.

The phenomenon can appear closer to the equator than the typical aurora, and is often accompanied by a "fence" of jagged green dots dancing next to it.

Nobody knows what causes Steve, but scientists agree it's not just auroras.

The auroras appear when charged particles from the sun sail through space and crack along the lines of the Earth's magnetic field. Meanwhile, Steve is a river of hot and turbulent gases that appear independent of solar weather.

The researchers believe that the "Steve" phenomenon may be the result of some local processes in the ionosphere, the level of the Earth's atmosphere that extends between 50 and 600 miles (80 to 1,000 kilometers) above the Earth's surface, below the planet's magnetic field.

And now, there is a newly discovered feature of "Steve", appearing only in the lower ionosphere, that has scientists confused about the ethereal lights again.

In a study published October 1 in the journal AGU Advances, NASA researchers reviewed hundreds of hours of "Steve" footage that scientists recorded to search for a strange new structure they called "lines." Sometimes these tiny streaks of green light are seen stretching horizontally from the bottom of Steve's green fence, and bend back for 20 to 30 seconds before disappearing from view.

And as with everything in Steve's phenomenon, no one really knows what these lines are. But a new research paper has attempted to define some basic characteristics.

For starters, the long, tube-like appearance of the lines can be an optical illusion, and according to the researchers, the lines behave like small points of light, which appear elongated to us due to motion blur.

The team found that each line shares a physical connection with the fence structure above it, and each line moves along the same magnetic field lines.

The lines also seem difficult to explain where they formed, and according to the team's calculations, the lines appear only low in the ionosphere between 62 and 68 miles (100 to 110 kilometers) above Earth.

This makes the lines "the lowest visual characteristic and the smallest scale associated with a stiff," the researchers wrote in the study.

One clue to the origins of the stripes comes from their green color, which matches the color of Steve's fence. According to the researchers, this green wavelength is related to the emissions of atomic oxygen into the atmosphere.

The team wrote that it is possible that the turbulent particles inside "Steve" collide with the surrounding oxygen and heat up rapidly, causing small green fires in the sky to roll down the fence as they slowly fade away.

"Steve's lines are very new to science," Elizabeth Macdonald, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

Source: Science

By:Nadeemy Haded