The European Space Agency’s (ESA) Solar Orbiter spacecraft has delivered the most detailed images of the sun’s surface to date. These images, taken in March 2023 from a distance of approximately 74 million kilometres, were released on November 20. They provide unprecedented insights into the photosphere, the layer of the sun responsible for emitting visible light. The photos reveal the intricate and dynamic patterns of granules—plasma cells roughly 1,000 kilometres wide—formed by convection as hot plasma rises and cooler plasma sinks.
Sunspot Activity and Magnetic Fields Analysed
The images highlight sunspots as cooler, darker regions on the photosphere, where intense magnetic fields disrupt the movement of plasma. The Polarimetric and Helioseismic Imager (PHI) on board the Solar Orbiter produced detailed maps of these magnetic fields, identifying their significant concentration in sunspot regions. According to Daniel Müller, ESA Project Scientist for Solar Orbiter, these observations are essential for understanding the sun’s dynamic processes. The sunspots appear colder because magnetic forces restrict normal convection, causing a decrease in surface temperature.
New Data on Solar Rotation and Winds
A velocity map, known as a tachogram, has also been shared, illustrating the speed and direction of material movement on the sun’s surface. Blue regions represent plasma moving towards the spacecraft, while red areas show plasma moving away, revealing the sun’s rotational dynamics. Additionally, magnetic fields in sunspot regions were seen to disrupt the surface material further.
The sun’s outer atmosphere, the corona, was imaged by the spacecraft’s Extreme Ultraviolet Imager. Plasma loops protruding from the sun, visible in these images, are connected to sunspots and contribute to the solar wind. This solar wind, when reaching Earth, often results in auroral displays.
Future Missions to Study Solar Poles
The Solar Orbiter, launched in 2020 as a joint mission with NASA, aims to capture unprecedented views of the sun’s poles. These observations are scheduled for 2025, when the spacecraft’s orbit will align for a direct perspective. The recent imaging involved the assembly of 25 smaller images, a complex process now expected to accelerate for future releases.