Why the sun’s mysteries could soon be revealed

Our sun is such an enduring presence in our sky that it can feel like an old friend. But, with a blinding light that confounds traditional telescopes and scorches most space probes, much about it remains a mystery. 

That could soon change, with a trio of new solar observatories poised to revolutionize our view of our solar companion, its relationship to our world, and perhaps even other star systems.

On Sunday evening, the newest solar observer rocketed into space by the light of a nearly full moon. The Solar Orbiter spacecraft – a collaboration between the European Space Agency and NASA – is designed to examine the sun from new angles, including taking the first ever look at its poles. 

It joins NASA’s Parker Solar Probe, which launched in 2018 and has recently taken its deepest dive into the sun’s atmosphere to sample the solar wind directly. Also coming online later this year is a 4-meter ground-based observatory, the Daniel K. Inouye Solar Telescope (DKIST) in Hawaii, which will be able to study the fainter parts of the sun. Late last month, DKIST released its first test images of the sun’s surface, depicting turbulent cell-like structures the size of Texas and dazzling the public. 

“These three together, they basically will define the future of the field,” says Nour Raouafi, project scientist of NASA’s Parker Solar Probe mission. “The next decade, I believe, will be the golden age of solar and heliophysics research.”

Unruly suns

The sun is continually producing “space weather” – coronal mass ejections, geomagnetic storms, and solar flares that can disrupt satellites and the power grid on Earth.

Researchers have long observed that these solar storms seem to wax and wane regularly, a phenomenon thought to be linked to the sun’s magnetic poles “flipping” every 11 years. But scientists haven’t been able to take a good look at the poles. All images of the sun have largely been from the same angle, roughly in line with the solar equator. 

“It’s like trying to study a three-dimensional ball with only looking at part of it,” says Holly Gilbert, NASA deputy project scientist for Solar Orbiter and director of the Heliophysics Science Division at NASA’s Goddard Space Flight Center. But Solar Orbiter’s path will take it over the sun’s top and bottom. “This allows us to look at the entire sun itself.”

We know from observing other stars that our sun is fairly tame – at least at the moment. Astronomers have spotted stars exploding violently, likely dousing planets in their orbit with radiation. Could our star be capable of that, too? 

“We’re so desperate to know if other stars are like our sun, if our sun is normal, or what our sun might have looked like in its past or in its future,” says James Davenport, a stellar astronomer at the University of Washington.

If researchers can figure out what mechanisms drive the sun’s activity, it could help put it in a cosmological context among other stars. And that knowledge, in turn, could help scientists piece together a more precise picture of how solar systems form – as well as what might make a planet habitable.

“All of life on the Earth comes from the energy that the sun produces,” says Jeff Kuhn, an astronomer at the University of Hawaii and a co-investigator on the DKIST Science Working Group. “And without a complete understanding of how that energy fluctuates, we don’t really understand our future.”

Earth’s atmosphere allows just enough of the sun’s light through while keeping the most harmful rays out. But scientists say the solar wind, the stream of plasma rushing away from our star, can rip atmospheres from planets. Earth’s magnetic field deflects much of the solar wind, protecting our atmosphere, but the same might not be the case for similar planets orbiting other stars.

The new observatories are built to glean more information about the solar wind and the mechanisms that drive it. As such winds are difficult to study directly around other stars, scientists hope these missions will reveal indirect ways to infer the flow of stellar winds in other star systems. That knowledge, in turn, could help improve models to identify potentially habitable distant worlds.

“The sun is basically the star in our backyard,” says David Alexander, a solar physicist at Rice University. So it becomes a laboratory for astrophysics, he says. “We’re taking that knowledge of the sun and then applying it to other stars.”

A stellar lineup

Parker, Orbiter, and DKIST weren’t planned to be a team. All three observatories were designed separately, and it was a coincidence that they will all begin to operate around the same time.

But that’s a coincidence scientists are eager to harness. The three observatories will work together in many ways, using their unique sets of instruments and paths to study regions of the sun from different angles, both literally and figuratively. 

“It’s a really good synergy with these different observatories,” Dr. Gilbert says. “Heliophysics is pretty difficult because it’s really a system science, and we have to understand how these different parts of the system are coupled,” from the solar atmosphere to the magnetic field, and how that interacts with the Earth’s atmosphere and magnetic field.

Together, astrophysicists expect this trio to revolutionize our view of the sun, resolving long-standing questions about stars and planets, and revealing surprises about our constant companion. 

“The sun is right there in front of us,” Dr. Kuhn says. It’s been “there in front of us forever, since civilization started. And yet now, only now in our lifetime are we looking at it and seeing as much detail that’s there.”