Today marks the release of the very first images taken by ESA’s Solar Orbiter. Having performed its first close approach to the Sun, Solar Orbiter has become the closest spacecraft to take images of the Sun. These stunning new images are already exciting scientists, showing the Sun at higher resolutions than we’ve ever seen before.
‘Campfires’ on the Sun
The new images were taken at the spacecraft’s recent close approach to the Sun as part of its commissioning phase. This is the phase in which the spacecraft and its instruments are being tested, and these images mark the end of it. But even though they are only intended as a test, they are already revealing new features.
This gallery of images shows tiny bright spots, or ‘campfires’, on the surface of the Sun. They are miniature solar flares that are too small to be viewed from the Earth. But don’t be fooled – they are still about the size of a European country! Captured by the Extreme Ultraviolet Imager (EUI), these campfires could hold answers to some of the mysteries of the Sun, such as coronal heating.
The Sun’s corona is its outermost layer. Similar to our atmosphere, it consists of rapidly moving plasma and gases, and is the origin of most solar flares and coronal mass ejections (CMEs). But it has one confusing feature – it is far hotter than the Sun’s surface, and even its core! No one knows why this is, but most theories involved changes in the Sun’s magnetic field: something that Solar Orbiter could help to understand.
A New Kind of Orbit
So what makes Solar Orbiter so special? It won’t be the closest spacecraft to the Sun (NASA’s Parker Solar Probe holds that title) but it will get to the closest point for a camera to survive. At the moment, it is about 77 million km away from the Sun. That’s about half the distance between the Earth and the Sun! At its closest point, it will be about half this distance again. Any closer, and the conditions are simply too harsh for the instruments to cope.
In addition, Solar Orbiter will be the first spacecraft to escape what’s known as the ecliptic. This is the plane in which all the planets in our solar system orbit. It means that Solar Orbiter will be able to get a different view of the Sun. It will be able to visit the poles, something that’s impossible to see from the Earth’s perspective! It’s hoped that this could give more insight into how the Sun’s magnetic field works.
Now that the commissioning phase is over, the spacecraft has moved into the cruise phase, and will reach its main science phase in early 2022. The long cruise phase is needed; in order to escape the ecliptic, Solar Orbiter needs to slingshot around 2 planets, using their gravity to boost it. To this end, it will perform 2 flybys of Venus and 1 of Earth.
The magnetic field of the Sun has a huge affect on the Earth, but we still don’t know much about it. Scientists aren’t even sure how it is generated. What we do know is that it drives a lot of the movement we see on the Sun. The various phenomena like sunspots and solar flares all follow magnetic field lines, caused by changes in the magnetic field. The Sun doesn’t have a uniform field like we do on Earth. Instead, its field lines twist and loop, and sometimes snap, causing energetic particles to stream out from it along the solar wind.
Heading out of the ecliptic is particularly useful for the Polarimetric and Helioseismic Imager (PHI), a cutting-edge magnetograph aboard Solar Orbiter that measures the magnetic field lines on the Sun. It will be able to monitor active regions of the Sun with strong magnetic fields that are not visible from Earth. Understanding these regions could help us further understand and maybe even predict future solar flares.
Solar Orbiter holds a lot of promise for solar physics. The data it collects over the next few years will give scientists a window on the Sun unlike any other. It will definitely be one to watch!