New explosion spotted on Sun's outer surface for the first time could help predict space weather, says NASA
For the first time, scientists have observed a new kind of explosion on the Sun's outermost layer: the corona. This discovery could explain why the corona is millions of degrees hotter than the lower atmospheric layers.
Called a magnetic explosion, it was captured by NASA's Solar Dynamics Observatory which confirms a 15-year-old theory. The explosion, which was captured by NASA's Solar Observatory, shows the Sun's outermost layer hurling a small amount of solar material called prominence into space.
The material fell back onto the Sun's surface, colliding with magnetic field lines, which in turn, set off a magnetic explosion.
The observations, says NASA, could also help scientists better predict space weather, and may lead to breakthroughs in the controlled fusion and lab plasma experiments.
The Sun is a giant magnetic star, which explains why the surface of the Sun is never still. The Sun's magnetic field causes disturbances such as twisting, towering loops and swirling cyclones that reach into the solar upper atmosphere, says NASA.
The snapping and realignment of the magnetic field lines — called magnetic reconnection — causes magnetic explosion.
Previously, scientists have documented a different kind of reconnection both on the Sun and around Earth — triggered spontaneously. These reconnections occur only in the presence of the right conditions.
They need to have a thin sheet of plasma — which makes up the Sun. Further, the plasma in that region of the Sun should allow only a small amount of electric current to pass through it.
However, the latest observation of the magnetic reconnection is different. Being triggered by a nearby eruption, scientists call this phenomenon a forced reconnection.
It is not as picky as its spontaneous counterpart, which means it can occur in a wider range of places on the Sun, regardless of the plasma's ability to let current pass.
"However, it can only occur if there is some type of eruption to trigger it. The eruption squeezes the plasma and magnetic fields, causing them to reconnect," says NASA.
The analysis suggested that forced reconnection might be causing the corona to reach such high temperatures. This could be explained by the temperature of prominence: before the eruption, the material had a fairly lower temperature.
It took about an hour for it to fall back down on the surface, but once it did, its temperature appeared to surge, says the study.
While spontaneous reconnection also can heat the Sun's plasma, forced reconnection seems to be doing a much better job: they are more effective heaters — raising the temperature of the plasma quicker, higher, and in a more controlled manner, says the study.
Furthermore, scientists suspect that forced reconnections could be driving other solar eruptions like flares and coronal mass ejection, which pose threats to Earth.
Studying these reconnections can help scientists better predict when disruptive high-energy charged particles might come speeding toward Earth.
"Our thought is that forced reconnection is everywhere," Abhishek Srivastava, a solar scientist at the Indian Institute of Technology (BHU), in Varanasi, India, said in a statement. "But we have to continue to observe it, to quantify it, if we want to prove that."
The new observations have been published in the Astrophysical Journal.