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Lift off, of the mighty Delta IV Heavy rocket

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In August 2018 in Cape Canaveral, Florida,

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NASA launched Parker Solar Probe to touch the Sun.

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After spending a few years spiraling closer to our star,

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the spacecraft has finally arrived.

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It’s amazing. Parker Solar Probe is touching the Sun.

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This is Nour Raouafi, the project scientist of the mission.

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He has been waiting for this moment since the beginning of his career.

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This is a dream come true.

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One of the major goals for the Parker Solar Probe mission is to

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fly through the solar corona and we are doing that now.

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So, what does it mean to touch the Sun?

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To answer that, we need to look at the Sun’s structure.

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Unlike Earth, our Sun doesn’t have a solid surface.

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It’s a giant ball of hot plasma that’s held together by its own gravity.

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Solar material flows out from the surface.

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But around the Sun, it’s bound by the Sun’s gravity and magnetic field.

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This material forms the Sun’s atmosphere—the corona. 

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Eventually, some of this hot and fast solar material escapes the pull of the Sun

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and gushes out into space as solar wind.

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The boundary that marks the edge of the Sun’s atmosphere

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is known as the Alfvén critical surface.

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We didn’t know exactly where this boundary was.

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But for the first time in history, a spacecraft has crossed it. 

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Parker Solar Probe ventured into the corona,

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touching solar material still bound to the Sun.

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The wispy corona is too faint to see most of the time,

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but it’s revealed during total solar eclipses.

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For centuries, we’ve been studying the Sun’s atmosphere during eclipses

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because it’s important for understanding how our star influences life in the solar system.

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But much about the corona remains a mystery.

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Two of the most challenging scientific mysteries in astrophysics occur in a region that we call solar corona.

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The first mystery is about the temperature.

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The corona is around 300 times hotter than the photosphere,

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the visible surface of the Sun below.

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Secondly, there’s a constant stream of particles flowing from the Sun known as the solar wind. 

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It accelerates up to millions of miles per hour out of the corona and we don’t know how.

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Solar wind can disrupt our satellites and technology.

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To better protect them, we need to go where the solar wind starts

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-- in the corona.

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So, heading there has been a key goal of NASA’s for a while.

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We first proposed the idea of sending a spacecraft to the Sun in 1958. 

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We didn’t have the technology to withstand the journey until the 2000s.

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Since its launch in 2018, Parker has been heading towards our star.

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Then in April 2021, during Parker’s eighth orbit around the Sun,

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the spacecraft was about 20 solar radii, or 8 million miles, from the Sun’s surface,

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when it crossed into the corona.

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This is a huge milestone. It took us over six decades to come to this point.

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As Parker entered the corona, its WISPR instrument took these images. 

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Streams of plasma surrounded the spacecraft

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and Parker’s other instruments detected that the magnetic conditions had changed.

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Outside the corona, solar wind gushes out,

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pushing solar material away at high speeds

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so that it can’t return back to the Sun’s surface. 

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Inside the corona, the Sun’s magnetic field becomes much stronger.

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Solar material is slower and tethered to the Sun.

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The bumpy ridges are created by huge flows of plasma traveling out of the corona.

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Instead of a smooth divide, Parker found that the boundary between these two sides is wrinkly.

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These bumpy ridges are created by huge flows of plasma traveling out of the corona.

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Scientists are not sure why this happens, but as Parker gets closer, we’re finding more clues.

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Before entering the corona, Parker had seen kinks in the solar wind

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where it would momentarily double-back on itself.

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Scientists called these features in the solar wind switchbacks.

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But no one knew how or where they formed.

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In 2021, the spacecraft finally tracked switchbacks to one of their origins.

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As Parker got even closer to the Sun,

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it detected bursts of switchbacks.

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Scientists traced these bursts all the way to the visible surface of the Sun.

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Here, we see distinct cells.

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As heat rises beneath, these convection cells churn and create funnels of magnetic energy above the surface.

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Scientists found that switchbacks form inside these funnels before rising into the corona and beyond.

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This is only one piece of the switchbacks puzzle though.

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Exactly how they form is still unknown.

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Over the next few years, Parker will keep looking for clues as it explores our Sun,

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the only star we can study up close.

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The Sun is also the only star known to support life,

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so understanding it is critical as we search for life beyond our solar system.

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That will link directly into the question——are we alone in this universe?

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And that is one of the biggest questions for humanity to answer.

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