The Parker probe reveals new secrets around the sun

Little West

Solar physicists, with data from NASA's Parker probe, have been able to identify the source of the solar wind that continuously strikes the Earth's atmosphere and uncover the strange magnetic field reflections that are accelerating these particles on their way to our planet.

A year ago, NASA's Parker Solar Probe probe flew toward the closest point of the sun to a satellite to date, collecting stunning data on the sun's aura, where temperatures reach 1 million degrees Celsius and the solar wind is released.

Solar wind particles
These accelerating particles of the solar wind interact with the Earth's magnetic field, generating magical aurora lights in the sky.

But it also has the potential to damage electricity and telecommunications networks on Earth, threaten orbiting satellites, and possibly endanger astronauts.

So solar physicists seek to learn more about the magnetic environment of the sun, and how the solar wind is formed, to improve the accuracy of prediction and avoid damage.

"We are a much more technological community than we were," said Stuart Bell of the University of California, Berkeley, the lead author of one of four articles published in the journal Nature on Dec. 4. "So the big disturbances from the sun are very dangerous."

"If we can predict space weather, we can turn off or isolate parts of the power grid, or shut down satellite systems that may be at risk."

Coronal holes
One of the main goals of the Parker probe was to discover the source of the "slow" solar wind and how it is accelerated in the solar aura.

The solar wind is known to consist of charged particles - most of which are protons and helium nuclei - that move very quickly along the sun's magnetic field lines.

These "fast" winds, which have a speed of 500 to 1,000 km / s, come from large holes in the solar corona at the north and south poles of the sun. But the source of the "slow" solar wind, which is denser and blows at no more than half of the "fast" wind speed, is still largely incomprehensible.

During each approaching encounter, the probe stood for more than a week above a coronal hole that emitted solar wind particles along the magnetic field lines passing in front of it, giving the instruments on board an unprecedented look at what was happening on the surface of the sun.

Thanks to the sun's extreme ultraviolet maps, Bell and colleagues were able to track winds and magnetic fields to their source (coronal holes), strongly suggesting that these holes are the source of the slow solar wind.

Coronal holes associated with sunspots are cooler and less dense areas of the surrounding aura.

Surprises
Unexpectedly, scientists have discovered a series of fluctuations in the magnetic field as it flows through the probe. During these periods, the field suddenly reversed direction by 180 degrees for a few seconds, before returning to its normal direction.

The author of the study is likely to be the result of a different type of plasma flows that may also be behind the phenomenon of heating associated with the solar wind.

The second surprise was caused by the dust that filled the probe repeatedly as it approached the perihelion, the closest point to the sun in the probe's orbit.

This dust consists of particles no larger than one micrometer (one thousandth of a millimeter), most likely from the asteroid debris or comets that melted near the sun and left behind the dust that now circles the sun.

"Studying the solar wind from the Earth is like studying the source of a waterfall from the bottom," says Bell. "The turbulence obscures what is going on upstairs.