Solar science enters a golden age

Although the closest star to Earth has been widely studied, the Sun still maintains some secrets. But perhaps not for long, as a veritable armada of solar science missions may soon unlock the last mysteries.

“In my opinion, the most interesting and significant solar discoveries have been coming from the Parker Solar Probe,” says Russell Howard, head of the U.S. Naval Research Laboratory’s Solar and Heliospheric Physics branch in Washington, D.C., and principal investigator for Parker’s Wide-field Imager for Solar PRobe (WISPR). Parker, which launched in 2018, “has been making both in situ and remote sensing observations from … much closer to the Sun than ever before.” Recently, the probe revealed that the Sun’s magnetic field is surprisingly complex far from the star. The simple dipole (like a bar magnet) structure researchers expected is there, Howard says, but overlaid with other structures as well, which scientists are now modeling to better understand.

Soon to observe in tandem with Parker is the European Space Agency/NASA Solar Orbiter spacecraft. After launching February 9, 2020, the probe made its first close pass of the Sun in mid-June. Its 10 instruments are working as expected — or better, says Howard, who is also principal investigator of the Solar Orbiter Heliospheric Imager (SoloHI).

SoloHI appears less affected by stray light than estimated and the magnetometer observed the signs of a coronal mass ejection event. Ultraviolet images show never-before-seen bright spots on the Sun. Small and ubiquitous, each is about a millionth to a billionth the size of a traditional solar flare. Researchers have christened them “campfires,” and suspect they are either miniature solar flares or perhaps related to nanoflares, which are thought to heat the Sun’s outer atmosphere, the corona.

The more sensors in the solar wind, the better, Howard says, because that gives scientists a more comprehensive view. Parker and Solar Orbiter are also joined by the Solar and Heliospheric Observatory, the two Solar Terrestrial Relations Observatory probes, the BepiColombo mission, and the ground-based Daniel K. Inouye Solar Telescope. “I am extremely excited about this ‘golden age’ of solar observations from five different space probes and the ground-based observations,” Howard says.

SpaceX’s Crew Dragon capsule prepares to dock with the International Space Station during the Demo-2 mission in this artist’s concept.