First results from close to the sun

Parker Solar Probe data paint a complex picture.

The first results from NASA’S Parker Solar Probe reveal that the Sun’s outer atmosphere is even more complex than scientists thought.

Launched in 2018, Parker’s mission is to dive ever closer to the Sun, eventually getting to just more than six million kilometres from its surface.

The two encounters to date have not gotten any closer than 24 million, but that’s less than half the distance between the Sun and Mercury, and twice as close as any prior spacecraft.

One surprise, says Daniel Verscharen, a space-plasma physicist at University College, London, who was not part of the Parker team, is that the Sun’s magnetic field has frequent “switchbacks” in which, for a few minutes, it suddenly reverses direction.

Something similar had been seen from further away, “but we had no idea that they would be so strong and would occur so often”. These reversals cause the velocity of the solar wind to alternately increase and decrease and may contribute to heating the Sun’s corona.

Also interesting, Verscharen says, is the discovery that the plasma has turbulent fluctuations or “instabilities”. Such turbulence is another way in which energy can be transferred from the magnetic field to the plasma, thereby heating it.