The European Space Agency (ESA) has published a striking image taken by the Solar Orbiter spacecraft. It shows the Sun and its hot corona.
Solar Orbiter was launched in 2020. The spacecraft moves in an elongated orbit, approaching the Sun at a distance of 42 million kilometers at perihelion, which is closer than the perihelion of Mercury’s orbit. This gives the Solar Orbiter the ability to make unique observations as well as take highly detailed images of the star’s surface.
The image published by ESA was taken on March 9, 2025, when the Solar Orbiter was 77 million km away from the Sun. The image is a composite one — it is made up of 200 individual frames. This produced the most detailed wide-angle portrait of the Sun in history.
The imaging was done at a wavelength of 17.4 nanometers, which corresponds to the extreme ultraviolet. This made it possible to capture the corona, the upper, thinnest and hottest layer of the Sun’s atmosphere. It consists of plasma heated to a temperature of a million degrees.
In addition to the corona, the Solar Orbiter image shows bright areas on the Sun’s surface. These are active regions that are surrounded by luminous coronal loops. The photo also shows prominences and dark filaments. They consist of relative cold material (~10,000 °C) “hanging” in a hot corona. It looks dark because it absorbs the radiation emitted beneath it. When viewed from the side, the filaments are called prominences. They extend over many thousands of kilometers and can last for days or even months.
Recall that in February, Solar Orbiter performed a gravitational maneuver that increased the inclination of its orbit. Thanks to this, the spacecraft was able to observe the polar regions of the Sun, which are not visible from Earth.
According to ESA
