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The Solar Orbiter mission’s first close pass of the sun in March revealed our star in a new light.
The spacecraft, which flew past the sun on March 26, returned a treasure trove of new images and perspectives after approaching within a third of the distance between the sun and Earth. Solar Orbiter’s heat shield reached around 932 degrees Fahrenheit (500 degrees Celsius), but performed as expected and protected the spacecraft on its historic first flyby.
Solar Orbiter is equipped with a multi-layer heat shield, a special coating called “Solar Black” made from burnt bones, and sliding doors that protect its instruments. The spacecraft also has solar panels that can get away from the worst heat and cooling elements inside. Together, these keep the spacecraft from melting while it studies the sun.
The mission, a joint effort between NASA and the European Space Agency, captured views of powerful flares and coronal mass ejections and vistas of the uncharted solar poles. The orbiter even spied a new feature dubbed the “Hedgehog”.
Scientists are just beginning to analyze the dataset captured by the orbiter’s 10 science instruments, but the information will deepen our understanding of how the sun behaves and how it affects space weather, which has a impact on Earth.
The sun is getting more active and Solar Orbiter has been watching its tantrums as the sun moves towards solar maximum.
Understanding the solar cycle is important because space weather caused by the sun – flares like solar flares and coronal mass ejection events – can impact the power grid, satellites, GPS, airlines, rockets and astronauts in space.
Every 11 years, the sun completes a solar cycle of calm and stormy activity and begins a new one. The current solar cycle, Solar Cycle 25, officially began in December 2019, and the next solar maximum, when the sun experiences peak activity, is expected to occur in July 2025.
During a solar cycle, the sun goes from a calm period to a very intense and active period. This activity is tracked by counting sunspots and how many are visible over time. Sunspots, or dark spots on the sun, are the origin of explosive flares and ejection events that release light, solar matter, and energy into space.
This puts Solar Orbiter, and another mission called Parker Solar Probe, in an ideal position to observe as we head towards solar maximum.
As Solar Orbiter takes detailed new images of the sun, scientists try to determine what they are seeing, comparing them to past solar observations from previous missions to determine if they are known features or unknown phenomena. One of these unexpected discoveries has been dubbed “the hedgehog,” a feature that stretches 15,534 miles (25,000 kilometers) across the sun and has spikes of hot and cold gas.
Currently, there is no explanation of what it is or how it formed in the sun’s atmosphere.
Solar Orbiter also captured film of an active area on the sun where the magnetic field releases loops rising through the atmosphere. The gas moves around the loops, cools, and creates “coronal rain” on the surface of the sun. The science team also saw “coronal foam,” where glowing gas creates lacy patterns on the sun.
“The images are truly breathtaking,” David Berghmans, principal investigator of the Extreme Ultraviolet Imager instrument at the Royal Observatory of Belgium, said in a statement. “Even if Solar Orbiter stopped taking data tomorrow, I would be busy for years trying to figure this all out.”
The Solar Orbiter mission is designed to study the sun’s outer atmosphere, called the corona, and determine how the sun interacts with the heliosphere, a bubble full of charged particles released by the sun that extends beyond the planets of our solar system. Space weather is created when the sun releases its flux of charged particles, called solar wind, along with the activity of the solar magnetic fields.
The crown can reach a million degrees Celsius (1.8 million degrees Fahrenheit), while the surface is 5,000 degrees Celsius (9,000 degrees Fahrenheit). Solar Orbiter could help determine why the temperature appears to be moving away from the sun’s core rather than falling.
The spacecraft’s instruments record data from the solar wind and magnetic fields and attempt to trace them back to their origins through the complex magnetic environment and back to the sun. Each instrument is responsible for observing and recording different aspects of the sun. The combination of this knowledge could one day be used to help scientists predict space weather from Earth.
Prior to the close flyby, Solar Orbiter was essentially upwind of Earth and observed solar winds and coronal mass ejections that may be heading towards Earth. Sending real-time data at the speed of light has alerted astronomers to monitor auroras on Earth.
But monitoring space weather in this way could also help us better protect our technological infrastructure and even the astronauts on the International Space Station. A future ESA mission, Vigil, will eventually be placed at a point on one side of the sun and observe coronal mass ejections heading towards Earth.
Solar Orbiter is now moving into position for a third flyby of Venus in September and its next close pass of the sun in October.
Further flybys will bring the spacecraft closer and closer to the star in the years to come. Gradually, the spacecraft will increase its orientation to study the polar regions of the sun more directly than ever before.
This unprecedented view of the poles could help scientists understand the complex polar magnetic environment of the sun, which could reveal the true heart of the solar cycle.