The Sun is constantly flooding the Solar System with a stream of highly charged particles called solar wind. The flow of this wind is not continuous but chaotic, with waves sloshing about and other features that we are still struggling to figure out.
A new discovery reported in the Journal of Geophysical Research: Space Physics has detailed solar wind blobs – bubble-like regions of the solar wind anywhere between 50 to 500 times the size of Earth. For the first time, researchers have shown that these blobs are hotter and denser than the rest of the solar wind.
The discovery was possible thanks to 45-year-old data collected by two German-NASA spacecraft called Helios 1 and Helios 2, which were launched respectively in 1974 and 1976. Lead author Simone di Matteo, a graduate student at the University of L’Aquila, discovered the peculiar patterns in the data.
The data showed perfect wave-like patterns without any flaws. And if there’s something that’s clear in science and in life, in general, it is that things that are too good to be true are usually false. Given that most people working on the probes have retired by now, di Matteo used the internet to find out if something in the probes might be the cause of the pattern.
“That was a red flag,” co-author Nicholeen Viall, from NASA Goddard Space Flight Center, said in a statement. “The actual solar wind doesn’t have such precise, clean periodicities. Usually, when you get such a precise frequency, it means some instrument effect is going on.”
di Matteo discovered a German manual for the probe that revealed there were two instruments used to measure the solar wind. The scientists wanted to be ready for different scenarios.
The pattern is produced by the spacecraft itself switching from one instrument to the other. Once this was taken into consideration, the researchers were able to find the true pattern, which turned out to be dotted trails of blobs coming out from the Sun's vicinity every 90 minutes or so. This is the closest to the Sun these blobs have been observed. Soon, they might be studied by NASA’s Parker Solar Probe, which will spend the next seven years whizzing closer and closer to the Sun until it flies just 4 million kilometers (2.5 million miles) from it.
“When a mission like Parker is going to see things no one has seen before, just a hint of what could be observed is really helpful,” Di Matteo said.
