NASA suspects sunquakes likely trigger deep underneath the solar surface
Our Sun periodically releases electromagnetic energy in explosions what scientists call solar flares. Followed by these events, scientists have seen seismic activity on solar surface- called sunquakes.
A sunquake releases acoustic energy in the wave form that ripples along the solar surface.
For decades it was believed that sunquakes were triggered by the magnetic forces in the outer atmosphere of Sun, where solar flares occur. However, NASA’s (SDO) Solar Dynamics Observatory data shows otherwise.
NASA launched SDO spacecraft in 2010 with the aim of studying sunspot and solar activity.
As per SDO observations, seismic activity is triggered deep below the Sun’s surface. In July 2011, unusually sharp ripples emanating from a strong solar flare were observed by SDO.
By using the Helioseismic and Magnetic imager instrument mounted on SDO, scientists tracked the source of the seismic activity 1,130 kilometres below the solar surface.
The instrument utilises on a technique called helioseismic holography. It measures the movement along the Sun’s surface.
Instead of the waves moving into the Sun from above, scientists observed the surface ripples of sunquake coming from deep below the Sun’s surface immediately after the occurrence of a flare.
The solar flare event in the outer atmosphere of Sun is thought to trigger a submerged source. This source in turn powers the seismic activity seen at the solar surface.
However, the exact reasons behind the sunquake activity are not known. Scientists hope to identify the submerged source by studying the additional sunquakes in coming future.
For more details: Submerged Sources of Transient Acoustic Emission from Solar Flares