The Solar Orbiter, a spacecraft jointly developed by ESA and NASA, has achieved a historic milestone: capturing the first-ever direct images of the Sun’s polar region. Since beginning its observations in 2021, the probe recently executed a crucial side trip to Venus. This manoeuvre significantly tilted its orbit, providing a unique vantage point from below the Sun’s equator, allowing it to clearly view the southern pole. These groundbreaking images, captured on March 16 and 17 from an angle 15 degrees below the equator, are now possible as the probe has reached its maximum 17-degree tilt.
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Traditionally, all planets in our galaxy and most spacecraft orbit the Sun along its equatorial plane. The Solar Orbiter’s Venus flyby uniquely positioned it to observe the Sun’s pole directly.
Three of the probe’s instruments were key to these observations:
- The Polarimetric and Helioseismic Imager (PHI) captured visible light images and mapped the Sun’s surface magnetic field.
- The Extreme Ultraviolet Imager (EUI) imaged the Sun in ultraviolet light.
- The Spectral Imaging of the Coronal Environment (SPICE) instrument gathered light from different temperatures of charged gas, revealing various layers of the Sun’s atmosphere.
What did Solar Orbiter see at the Sun’s southern pole? Simply put, its magnetic field is currently in disarray. The Sun’s magnetic field flips approximately every 11 years, a process expected to occur this year. While a typical magnet has distinct north and south poles, PHI revealed that both north and south polarity magnetic fields are present at the Sun’s south pole right now. ESA explained that “This happens only for a short time during each solar cycle, at solar maximum, when the Sun’s magnetic field flips and is at its most active.”
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After this flip, the magnetic field gradually reestablishes single polarities at the poles, a process taking five to six years to reach solar minimum, where the field is most orderly. These regular magnetic field flips (solar cycles) are not fully understood, and the Solar Orbiter’s unprecedented observations could be crucial to unlocking this knowledge.
Additionally, scientists used the SPICE instrument to take Doppler measurements of how fast clumps of solar material are moving. This data was used to create a velocity map, showing material movement within a specific solar layer. Such measurements are vital for understanding how the Sun ejects particles into space as solar winds, a primary objective of the Solar Orbiter mission.
