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.
The mission of Solar Orbiter
Being able to see an eruption take place and then sample the ejected gasses, either with its own instruments or those of another spacecraft, is one of Solar Orbiter’s principal scientific aims. It will allow a better understanding to be developed of solar activity and the way it creates ‘space weather’, which can disrupt satellites and other technology on Earth.
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 centigrade.
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.
Capturing the plasma journey
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.
For the spacecraft’s Energetic Particle Detector (EPD), the eruption was one of the most intense solar energetic particles events detected so far by the instrument.
RoCS on a mission with ESA and NASA
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.
RoCS - Rosseland Centre for Solar Physics has been a part of the mission from the start and their scientists and engineers play key roles on one of the remote sensing instruments: SPICE (Spectral Imaging of the Coronal Environment).
See also the article Solar Orbiter’s unprecedented view of the quiet corona (RoCS website)