Solar Orbiter has spotted a ‘tube’ of cooler atmospheric gases snaking its way through the Sun’s magnetic field. The observation 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 5 September 2022, as Solar Orbiter was approaching the Sun for a close pass that took place on 12 October. It is a tube of cool plasma suspended by magnetic fields in the hotter 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 susceptible to magnetic fields. All gas in the Sun’s atmosphere is a plasma because the temperature here is more than a million degrees.
The plasma in the snake is following a particularly long filament of the Sun’s magnetic field that is reaching from one side of the Sun to another.
“You're getting plasma flowing from one side to the other but the magnetic field is really twisted. So you're getting this change in direction because we're looking down on a twisted structure,” says David Long, Mullard Space Science Laboratory (UCL), UK, who is heading up the investigation into the phenomenon.
The movie has been constructed as a time-lapse from images from the Extreme Ultraviolet Imager onboard Solar Orbiter. In reality, the snake took around three hours to complete its journey but at the distances involved in crossing the solar surface that means the plasma must have been travelling at around 170 kilometres per second.
What makes the snake so intriguing is that it began from a solar active region that later erupted, ejecting billions of tonnes of plasma into space. This raises the possibility that the snake was a sort of precursor to this event – and Solar Orbiter caught it all in numerous instruments.
Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. It launched on 10 February 2020, and earlier this month celebrated its 1000th day in space.
More on ESA’s website.