Solar seismic activity: Sunquakes could be originating from deep within the Sun, NASA says

NASA on solar activity: Beneath the surface of the Sun there might lie the answers to the mystery around sunquakes, according to the US space agency National Aeronautics and Space Administration (NASA). For long, scientists have believed that these events were a result of magnetic forces or that the heated outer atmosphere was causing them. However, now, the Solar Dynamics Observatory (SDO) of NASA has found something that differs from this long-standing belief.

Sunquakes: What are they?

Sunquakes are the seismic activities that occur on the Sun during solar flares and these are events similar to earthquakes. During such events, acoustic energy is released along the solar surface in the form of rippling waves and they occur in the minutes that follow a solar flare, NASA said.

A solar flare is an outburst that occurs in the outer atmosphere of the Sun, during which material, energy as well as light is released.

The scientists suspected that the waves of the sunquakes dove down deep into the interior of the Sun through its surface, but it has been contradicted by the new findings of the SDO.

Sunquakes: What NASA has found

NASA said that back in 2011, the SDO observed a moderately strong flare followed by a sunquake having ripples that were unusually sharp. With the help of helioseismic holography using, scientists tracked the waves causing these ripples and traced their source. The helioseismic and Magnetic Imager of the SDO measured how the solar surface moved.

The space agency found that the waves were not travelling into the Sun, but instead, sunquake ripples occurring on the solar surface originated from deep underneath the surface immediately after the occurrence of a solar flare. It was found that the acoustic source lied a whopping 700 miles or around 1,127 km underneath the solar surface, in a significant contrast to what the scientists earlier believed.

The scientists are now of the view that there is a submerged source causing these waves and this source is somehow triggered due to the solar flares. The exact mechanism causing these sunquakes, however, has not yet been identified. The scientists would now continue to observe other sunquakes for clues about the mechanism, NASA said.