A NASA spacecraft became the first to “touch the sun,” scientists announced Tuesday — a long-awaited milestone and a potential giant leap in understanding the sun’s influence on the solar system.
“For centuries, humanity has only been able to observe this atmosphere from afar,” Nicola Fox, director of NASA’s heliophysics division, said at a news conference. “Now … we have finally arrived. Humanity has touched the sun.”
The spacecraft, launched three years ago in an effort to study the sun and its dangers, will help scientists uncover significant and unknown information about Earth’s closest star, including how the flow of the sun’s particles can influence the planet. Thomas Zurbuchen, the associate administrator for NASA’s science mission directorate, which looks at how discoveries in one scientific discipline are connected to other areas of study, said in a statement that the Parker Solar Probe’s success in “touching the sun” was “a monumental moment for solar science and a truly remarkable feat.”
“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,” Zurbuchen said. A NASA spokesperson did not immediately respond to a request for comment early Wednesday.
Justin Kasper, the study’s lead author and deputy chief technology officer at BWX Technologies, told The Washington Post that “touching” the sun with a probe, a long-sought mission, was “very exciting.”
“It feels like visiting a planet for the first time,” said Kasper, who is also a professor at the University of Michigan. “That was the sense of excitement we got.”
The spacecraft’s brush with the sun is the culmination of a mission more than 60 years in the making. Scientists have long tried to get a close look at the sun, the source of Earth’s light and heat, as well as solar storms that could disrupt satellites and fry electric grids.
After the nation’s top scientists in 1958 compiled a list of missions that they thought NASA, then a brand-new space agency, should pursue, dreams such as the Hubble Space Telescope, the twin Voyager spacecraft and the Apollo program all eventually became realities. But the goal of reaching the sun remained elusive.
The challenges of touching the sun are well-documented. The Earth’s closest star does not have a solid surface and is described in one NASA video as “a giant ball of hot plasma that’s held together by its own gravity.” The material from the sun helps form the star’s atmosphere, the corona, an area significantly hotter than the actual surface of the star. The corona is about 1.8 million degrees Fahrenheit at its hottest point, compared with the surface of the sun at around 10,340 degrees Fahrenheit. Some of those hot and fast particles from the corona end up gushing into space as solar wind.
“By the time it reaches Earth, 93 million miles away, the solar wind is an unrelenting headwind of particles and magnetic fields,” NASA noted.
Experts have long struggled to predict space weather events because of the ferocious environment around the sun. Scientists have also tried to learn more about the boundary called the Alfvén critical surface, which marks the end of the solar atmosphere and the beginning of the solar wind.
In August 2018, NASA launched the Parker Solar Probe on its journey to the sun in hopes of learning more about space weather, one of Earth’s biggest natural threats. Although the Parker probe discovered in 2019 that switchbacks, or magnetic zigzag structures in the solar wind, were close to the sun, much remained unknown about how and where they formed.
Then, on April 28, the Parker Solar Probe crossed the Alfvén critical surface for the first time and finally entered the solar atmosphere on its eighth flyby of the sun. Data from the spacecraft showed that it encountered the specific magnetic and particle conditions of the corona at around 8.1 million miles above the solar surface, according to NASA.
“This is a dream come true,” Nour Raouafi, the project scientist for the Parker Solar Probe, told NASA. “One of the major goals for the Parker Solar Probe mission is to fly through the solar corona — and we are doing that now.”
For the first time, NASA said, the spacecraft “found itself in a region where the magnetic fields were strong enough to dominate the movement of particles there.”
Although it would take months to confirm the data, Kasper said, the conditions discovered by the Parker Solar Probe were definitive proof that the spacecraft had passed the Alfvén critical surface and entered the solar atmosphere.
“It was probably July of this year where we were like, ‘This is real. It indeed crossed into the sun’s atmosphere for about five hours,’” Kasper said. “We had been smiling and trying to keep our mouths shut until we were sure.”
The successful flyby will not be the last, as the spacecraft is expected to fly through the corona next month. Fox said in a statement that “touching” the sun and future missions signal how “the opportunity for new discoveries is boundless.”
“I’m excited to see what Parker finds as it repeatedly passes through the corona in the years to come,” Fox said.
As Parker takes closer passes by the sun, it is likely to reveal more information on solar phenomena and help people understand and forecast the kind of “extreme space weather events that can disrupt telecommunications and damage satellites around Earth,” according to NASA.
Kasper said he remained stunned months later about what it could mean for understanding the solar system.
“I don’t know if I’ll really process that we crossed over into the sun’s atmosphere,” he said. “It’ll probably be a while before it sinks in.”
Sarah Kaplan and Ben Guarino contributed to this report.