The Solar Orbiter mission has provided the most detailed images yet of the Sun's visible surface, capturing stunning views of sunspots and plasma flows. The images offer unprecedented insights into the Sun's magnetic field and outer atmosphere, potentially unlocking new secrets of solar activity.
The European Space Agency (ESA) and NASA's Solar Orbiter, launched in February 2020, obtained the images on March 22, 2023, from a distance of around 74 million kilometres. These images, released on November 20, 2024, provide a detailed view of the Sun's dynamic and grainy surface known as the photosphere, the layer responsible for emitting the sunlight we see.
According to the ESA, “The mission reveals the highest-resolution full views of the Sun's visible surface (photosphere) to date. They are assembled from images made by the spacecraft's Polarimetric and Helioseismic Imager (PHI). This instrument not only takes images in visible light, but also measures the direction of the magnetic field, and maps how fast and in which direction different parts of the surface are moving.”
The Solar Orbiter mission employs six advanced imaging instruments — including the Extreme Ultraviolet Imager (EUI) and PHI — to explore the Sun.
Daniel Muller, Solar Orbiter's Project Scientist, added, “These new high-resolution maps from Solar Orbiter's PHI instrument show the beauty of the Sun's surface magnetic field and flows in great detail. At the same time, they are crucial for inferring the magnetic field in the Sun's hot corona, which our EUI instrument is imaging.”
The photosphere's temperature ranges between 4,500 and 6,000 degrees Celsius, and it is dotted with sunspots — cooler, darker regions caused by intense magnetic fields. Sunspots, some larger than Earth, disrupt the transfer of heat from the Sun's interior, creating these distinct cooler regions.
The PHI also generated magnetograms, highlighting areas of concentrated magnetic activity, and velocity maps, or “tachograms,” revealing the speed and direction of material movements on the Sun's surface. The EUI focused on the solar corona, the outermost layer of the Sun, where temperatures soar to one million degrees Celsius. These images helped scientists understand why the Sun's corona is vastly hotter than the photosphere below.
To produce such detailed imagery, the spacecraft had to rotate after each capture, creating mosaics from 25 images. This careful manoeuvre allowed the Orbiter to piece together a full view of the Sun's face.
This release builds on the one from two years ago, when the mission unveiled full images of the Sun captured by the spacecraft's EUI and SPICE instruments on March 7, 2022.
