Solar Orbiter spotted a “tube” of cooler atmospheric gases meandering through the Sun’s magnetic field. The sighting provides an intriguing new addition to the zoo of features revealed by the ESA-led Solar Orbiter mission, especially since the snake was a precursor to a much larger eruption.
The snake was seen on September 5, 2022, as Solar Orbiter approached the Sun for a close pass that took place on October 12. It is a tube of cold plasma suspended by magnetic fields in the warmer surrounding plasma of the Sun’s atmosphere.
Plasma is a state of matter in which a gas is so hot that its atoms begin to lose some of their outer particles, called electrons. This loss makes the gas electrically charged and therefore sensitive to magnetic fields. Any gas in the Sun’s atmosphere is plasma because the temperature there is above a million degrees centigrade.
The plasma in the snake follows a particularly long filament of the Sun’s magnetic field that runs from one side of the Sun to the other.
“You get plasma flowing side to side, but the magnetic field is really twisted. So you get this change in direction because we’re looking down at a twisted structure,” says David Long, Mullard Space Science Laboratory (UCL), UK, who is leading the investigation into the phenomenon.
The film was constructed as a time-lapse from footage from the Extreme Ultraviolet Imager aboard Solar Orbiter. In reality, the snake took about three hours to make its journey, but at the distances involved to cross the solar surface, that means the plasma must have been moving at about 170 kilometers per second.
What makes the snake so intriguing is that it started from an active solar region which then erupted, ejecting billions of tons of plasma into space. This raises the possibility that the snake was some sort of precursor to this event – and Solar Orbiter captured it all in many instruments.
For the spacecraft’s Energetic Particle Detector (EPD), the flare was one of the most intense solar-energetic particle events detected by the instrument so far.
“It’s a really nice combination of datasets that we only get from Solar Orbiter,” says David.
More intriguingly, plasma from this eruption, known as a coronal mass ejection, swept past NASA’s Parker Solar Probe, allowing its instruments to measure the contents of the eruption.
Being able to witness an eruption and then sample the ejected gases, either with its own instruments or those of another spacecraft, is one of the main scientific objectives of Solar Orbiter. It will provide insight into solar activity and how it creates “space weather,” which can disrupt satellites and other technologies on Earth.
Solar Orbiter is an international collaborative space mission between ESA and NASA, operated by ESA. It launched on February 10, 2020, and earlier this month celebrated its 1,000th day in space.