Parker’s spiral trajectory brings it slowly closer to the Sun and during the last few passes, the spacecraft was consistently below 20 solar radii (91 percent of Earth’s distance from the Sun), putting it in the position to cross the boundary – if the estimates were correct. Based on remote images of the corona, estimates had put it somewhere between 10 to 20 solar radii from the surface of the Sun – 4.3 to 8.6 million miles. Until now, researchers were unsure exactly where the Alfvén critical surface lay. Importantly, beyond the Alfvén critical surface, the solar wind moves so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun – severing their connection. Solar material with the energy to make it across that boundary becomes the solar wind, which drags the magnetic field of the Sun with it as it races across the solar system, to Earth and beyond. That point, known as the Alfvén critical surface, marks the end of the solar atmosphere and beginning of the solar wind. As rising heat and pressure push that material away from the Sun, it reaches a point where gravity and magnetic fields are too weak to contain it. But it does have a superheated atmosphere, made of solar material bound to the Sun by gravity and magnetic forces. Unlike Earth, the Sun doesn’t have a solid surface. Three years after launch and decades after first conception, Parker has finally arrived. Parker Solar Probe launched in 2018 to explore the mysteries of the Sun by traveling closer to it than any spacecraft before. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.” Closer Than Ever Before “We see evidence of being in the corona in magnetic field data, solar wind data, and visually in images. “Flying so close to the Sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere – the corona – that we never could before,” said Nour Raouafi, the Parker project scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. The first passage through the corona – and the promise of more flybys to come – will continue to provide data on phenomena that are impossible to study from afar. Halving the distance to the Sun since then, Parker Solar Probe has now passed close enough to identify one place where they originate: the solar surface. But how and where they form remained a mystery. In 2019, Parker discovered that magnetic zig-zag structures in the solar wind, called switchbacks, are plentiful close to the Sun. “Not only does this milestone provide us with deeper insights into our Sun’s evolution and its impacts on our solar system, but everything we learn about our own star also teaches us more about stars in the rest of the universe.”Īs it circles closer to the solar surface, Parker is making new discoveries that other spacecraft were too far away to see, including from within the solar wind – the flow of particles from the Sun that can influence us at Earth. “Parker Solar Probe “touching the Sun” is a monumental moment for solar science and a truly remarkable feat,” said Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. Just as landing on the Moon allowed scientists to understand how it was formed, touching the very stuff the Sun is made of will help scientists uncover critical information about our closest star and its influence on the solar system. The new milestone marks one major step for Parker Solar Probe and one giant leap for solar science. NASA’s Parker Solar Probe has now flown through the Sun’s upper atmosphere – the corona – and sampled particles and magnetic fields there. The results have been published in Physical Review Letters and accepted for publication in the Astrophysical Journal.įor the first time in history, a spacecraft has touched the Sun. 14 in a press conference at the 2021 American Geophysical Union Fall Meeting in New Orleans. A major milestone and new results from NASA’s Parker Solar Probe were announced on Dec.
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