See the First-Ever Direct Images of the Sun’s South Pole, Captured by the Solar Orbiter Spacecraft
The spacecraft’s tilted orbit will allow scientists to investigate the mechanisms behind space weather that impact crucial human activity on Earth
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Though humans have been observing the sun since the dawn of our species, the European Space Agency (ESA) has just revealed images featuring a perspective on the star that no one has ever seen before: its south pole.
Solar Orbiter—a joint ESA and NASA mission—captured the first views of the polar region in mid-March, when it was at an angle of 15 degrees below the solar equator. A few days later, the orbiting spacecraft reached a viewing angle of 17 degrees.
All pre-existing images of the sun were taken from within about 7 degrees of its equator. That’s because every spacecraft orbiting the star, along with every planet in our solar system, swoops around the sun in a flat disk called the ecliptic plane, which is tilted just 7.25 degrees relative to the sun’s equatorial plane. (The Ulysses spacecraft is the only one to have passed over the sun’s poles, but it didn’t have a camera.)
As such, “we’ve had a good view of [the] centermost part of the sun’s disk,” Daniel Müller, a heliophysicist and project scientist for the Solar Orbiter mission, tells Scientific American’s Meghan Bartels. “But the poles are effectively not visible, because we always see them almost exactly edge-on.”
Now, however, scientists have tilted Solar Orbiter’s trajectory out of the ecliptic plane, allowing it to view the south pole directly. The new images were captured by three of the spacecraft’s instruments: the Polarimetric and Helioseismic Imager (PHI), the Extreme Ultraviolet Imager (EUI) and the Spectral Imaging of the Coronal Environment (SPICE) instrument.
“Being able to observe the poles is vital for understanding how the sun’s magnetic field operates on a global scale, leading to an 11-year cycle in the sun’s activity,” says Lucie Green, a solar physicist at University College London who has been working with Solar Orbiter since 2005, to Space.com’s Robert Lea.
Our sun’s magnetic field flips every 11 years or so, and when it does, it reaches a peak level of solar activity, per the ESA statement. Scientists announced that the sun had reached one such “solar maximum” last fall, which helps explain the recent bouts of intense solar flares.
The new observations from the Solar Orbiter’s PHI have also revealed that the sun’s magnetic field is “currently a mess” at the south pole, featuring both north and south polarity magnetic fields, per the ESA. That’s a clear sign of the solar maximum.
“When the sun is at its minimum, you have a north pole and a south pole, each with its own magnetic polarity,” Anik De Groof, Solar Orbiter’s mission manager, tells the New York Times’ Jonathan O’Callaghan. But during solar maximum, the star is in magnetic chaos. Solar Orbiter’s observations indicate that there is currently no dominant polarity at either pole, De Groof adds.
“Although the models predicted that the field should be mixed up, it’s something else to actually see it,” Green tells the Guardian’s Hannah Devlin.
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Despite its cyclical nature, scientists still struggle to predict the exact timing and power of each solar maximum and the magnetic flip, after which the poles should slowly regain their distinct polarities before the process starts all over again. Accurately forecasting solar activity would carry significant implications for human activity on or near Earth, where solar flares can disrupt radio communication and even endanger astronauts.
Along those same lines, the SPICE instrument measured the speed of solar material within different layers of the sun, which can provide insight into solar wind: charged particles the star ejects into space that sometimes cause power outages on Earth.
With further observations, scientists hope to create a model of the sun that will allow them to predict space weather. “This is the Holy Grail of solar physics,” Christopher Owen, a researcher at University College London who specializes in solar wind, tells the BBC’s Pallab Ghosh. “Solar Orbiter will enable us to get to the bottom of some of the basic science of space weather. But a little more work needs to be done before we get to the point where we see signals on the sun that we can rely on to predict eruptions that might hit the Earth.”
Scientists still have a lot to investigate within this unique set of data, according to the ESA. And the polar perspective will become increasingly complete in the coming months: Solar Orbiter has also imaged the sun’s north pole in another first, with researchers expecting to receive data from that flyby and the spacecraft’s first full “pole-to-pole” orbit by October.
