Physicists report the first definitive measurements of the sun's electrical field

Astronomers and physicists have been studying the sun for a very long time, and despite all the intense study, much of what goes on in the sun is a mystery. As the Parker Solar Probe gets closer to the sun, scientists are learning new information about the star. A new study published by physicists from the University of Iowa has reported the first definitive measurements of the sun's electrical field.

The study also offers information on how the electrical field interacts with the solar wind, which is the fast-flowing current of charged particles that can impact activities on Earth, including satellites and telecommunications. In their study, the physicists calculated the distribution of electrons within the electric field of the sun. They could do this thanks to the Parker Solar Probe being within 0.1 astronomical units, or 9 million miles, from the sun.

That distance represents the closest any spacecraft has approached in history. The distribution of the electrons allows physicists to discern the size, breadth, and scope of the electric field of our home star more precisely than ever possible. Researcher Jasper Halekas says that the key point to understand is that measurements such as this can't be made from far away from the sun. They can only be made up close.

He likens trying to study the electrical field of the sun from a distance to trying to study a waterfall by looking at a river a mile downstream. Measurements were made from 0.1 astronomical units from the sun, which is like actually being in the waterfall. At that distance from our home star, the solar wind is still accelerating.

The sun's electric field comes from the interaction of protons and electrons generated when hydrogen atoms are ripped apart within the intense heat generated by fusion within the sun. In that environment, electrons with masses 1800 times less than that of protons are blown outward because they were less constrained by gravity than their heavier proton siblings. Halekas says that as the electrons are trying to escape, protons are trying to pull them back.

He says that there is a boundary of energy between the electrons that escape and ones that don't, which can be measured. Being so close to the sun, the researchers were able to make accurate measurements of the distribution of the electrons before collisions occur further out, distorting the boundary and obscuring the electric field.