The European Space Agency has published a series of images taken by the Solar Orbiter probe on November 22, 2023. These are the most detailed images of the Sun’s surface to date.
The images were taken with the PHI and EUI instruments installed on Solar Orbiter. PHI can take visible light images, measure the magnetic field, and map the speed and direction of various surface areas. EUI takes images of the Sun in ultraviolet light.
A visible-light image of PHI shows the Sun’s surface (photosphere) as it is: a glowing, hot plasma (charged gas) that is constantly moving. Almost all radiation comes from this layer, which has a temperature of 4500 to 6000 °C. Below it, hot dense plasma moves in the convection zone of the Sun, like magma in the Earth’s mantle. As a result of this motion, the photosphere takes on a grainy appearance. The most prominent elements in the image are the sunspots. They are colder than their surroundings and therefore emit less light and appear dark to us.
PHI’s magnetic map, or “magnetogram”, shows that the Sun’s magnetic field is concentrated in sunspot regions. It points either outward (red) or inward (blue) where the sunspots are located. A strong magnetic field explains why the plasma inside sunspots is colder. Normally, convection moves heat from inside the Sun to its surface, but it is disrupted because charged particles are forced to follow the dense magnetic field lines in and around the sunspots.
The speed and direction of matter near the Sun’s surface can be seen on the PHI’s velocity map, also known as a “tachogram.” Blue indicates movement toward the spacecraft and red indicates movement away from the spacecraft. This map demonstrates that although the plasma on the Sun’s surface generally rotates with the Sun’s rotation on its axis, it is pushed outward near sunspots.
Finally, an EUI-obtained image of the solar corona shows what is happening above the photosphere. Above the active sunspot regions, red-hot plasma can be seen protruding outward. The million-degree plasma follows the magnetic field lines coming out of the Sun, often connecting neighboring sunspots.
The images were taken when the Solar Orbiter was less than 74 million kilometers from the Sun. Being so close to the Sun, each high-resolution image taken by PHI and EUI covers only a small portion of the star. After taking each individual image, the spacecraft had to be tilted and rotated to take an image of the next part of the Sun’s surface. Then, they were stitched together. The PHI and EUI mosaics consist of 25 images each, taken over a period of more than four hours. The diameter of the Sun’s disk in the full version is nearly 8,000 pixels, revealing an incredible amount of detail.
We previously covered how Solar Orbiter detected the largest solar flare since 2017.
Provided by ESA
