on March 26the Solar Orbiter spacecraft, operated by European Space Agency (ESA) in partnership with NASA, has come closer to the Sun’s corona than it has ever been. During the point in their orbit closest to our star, known as perihelion, all 10 instruments operated simultaneously, working together to collect important and previously unseen data.
Mercury, the closest planet, is more than 57 million km from the Sun. Solar Orbiter came even closer, coming within 48 million km of our host star, from where it could be observed like never before in history.
For the first time, the entire Sun has been recorded, including its poles, which are often difficult to observe, due to the point of view of the Sun. Terra in orbit around the solar equator.
NASA probe recorded hard-to-reach areas on the Sun
The polar regions are believed to be extremely important to the Sun’s magnetic fields, which play an essential role in solar activity. However, because the poles are so hard to see, we don’t know what happens to the magnetic fields in these areas.
With its complex array of instruments, Solar Orbiter offers unprecedented insight into these enigmatic regions. Two films made by the spacecraft were released by NASA. The first, recorded the day after perihelion, and the other, four days later.
This first film highlights both full-length images of the disk, taken by the probe’s Full Sun Imager (FSI) telescope, and detailed images of a smaller region, taken using the High Resolution Imager (HRIEUV) telescope. It is possible to see the coronal strips highly excited by solar activity.
The film then approaches the HRIEUV target region, where smaller-scale coronal loops can be seen. According to NASA, the color was artificially added because the original wavelength detected by the instrument is invisible to the human eye.
In the second film, the spacecraft spotted a fascinating and mysterious feature of our star, known as the “hedgehog”, that astrophysicists still haven’t figured out exactly what it is or how it formed. It is only known that it exists and occupies an area of approximately 25,000 km in diameter.
Images captured in extreme ultraviolet by Solar Orbiter, at a wavelength of 17 nanometers, finally managed to reveal its activity. And what an activity: extremely hot and less hot spikes of gas shoot in all directions from the solar corona, showing the strength of its magnetic field.
Solar wind passes Pluto’s orbit
According to Science Alert, the main purpose of the Solar Orbiter spacecraft is to help scientists understand the effect the Sun has on the entire heliosphere, or the solar sphere of influence defined by the solar wind, whose boundary passes from the orbit of Pluto. This solar wind blows particles and gases into interplanetary space, mixing with the planets with tangible effects.
The closer it gets to the Sun, the better it will be able to show scientists how the solar wind blows. Just before reaching perihelion on March 21, the spacecraft detected a stream of energetic particles, and even at that distance, the observation was revealing.
The most energetic particles arrived first, followed by the least energetic. This suggests that the particles were not produced close to Solar Orbiter’s position, but close to the Sun’s surface.
Starting in 2025, Solar Orbiter will use the gravitational pull of Venus to gradually increase the inclination of its orbit. This will allow the spacecraft’s instruments to investigate the solar poles from a more top-down vantage point.
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