The Sun’s upper atmosphere, or corona, in ultraviolet light
ESA and NASA/Solar Orbiter/EUI team
These fiery images are the clearest views of the sun ever, taken by the Solar Orbiter spacecraft.
Solar OrbiterA joint mission between the European Space Agency (ESA) and NASA, it is the most advanced instrument to orbit the sun and has been sending information back to Earth ever since. He arrived there in 2020.
These images were taken in March 2023, when the Solar Orbiter was less than 74 million kilometers from the sun. The photo above was taken using ultraviolet light, revealing the sun’s outer atmosphere, or corona, in great detail, and shows the 1 million ºC plasma sizzling along the sun’s magnetic field lines. Bright light from the Sun’s surface usually obscures the corona, so the corona can be seen if you block visible light normally, which happens during an eclipse, or if you look at it using, say, ultraviolet light.
To create a complete image of the Sun’s corona, many higher zoom images had to be stitched together, resulting in a complete mosaic of 8000 pixels. In the future, we will get two similar high-resolution pictures of the Sun every year from the Solar Orbiter, according to ESA.
The Sun in visible light taken by the Polarimetric and Helioseismic Imager on the Solar Orbiter spacecraft
ESA and the NASA/Solar Orbiter/PHI team
This second image is what the surface of the sun, or photosphere, looks like when viewed by the Solar Orbiter in visible light, the same light we can see with our own eyes. This solar layer has a temperature of around 4500 to 6000 °C. The dark regions here are sunspots that are cooler and emit less light than their surroundings.
Map of the Sun’s magnetic field measured by polarimetric and helioseismic images from the Solar Orbiter spacecraft.
ESA and the NASA/Solar Orbiter/PHI team
Viewed using the spacecraft’s magnetic instruments, the sun’s magnetic field can be seen to be concentrated around sunspot regions (see image above). The field pushes charged particles away from these regions, making them cool and dark.
A velocity map or tachogram showing the speed and direction of material movement on the surface of the sun
ESA and the NASA/Solar Orbiter/PHI team
Solar Orbiter can also track the speed and direction of plasma moving across the sun’s surface. In this velocity map (above), called a tachogram (above), blue indicates motion toward the spacecraft and red away from it, showing that the plasma mostly rotates with the sun’s rotation, but deviates around sunspot regions.
This collection of images will help scientists understand the behavior of the sun’s corona and photosphere. The Solar Orbiter will also image the solar poles, the top and bottom of the star, which we have not seen before. We currently do not understand the solar poles very well and researchers expect these areas to be very different from other regions of the sun.
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