Sharpest-ever pics of sun’s surface reveal previously unseen whirlpools
In all pictures taken of the Sun’s surface in the past century, the edges of its convection cells were blurred. For decades, solar physicists wondered if those edges were really frayed or if a more powerful telescope could reveal more detail. New images have settled the debate.
Scientists using the world’s largest solar telescope have captured the highest-resolution pictures yet of the Sun’s surface, revealing small, violent plasma whirlpools churning across it.
The images were captured by the NSF Daniel K. Inouye Solar Telescope in Hawaii — a 4-metre mirror perched near the 10,000-foot summit of the Haleakalā volcano. Paired with a FastCam camera shooting 740 frames per second, the telescope observed a magnetically active region called NOAA 14060 at a wavelength of 416 nanometres.
After advanced image processing, the team achieved a resolution of 19 km — like spotting a 10-rupee coin in Mumbai from Pune. That is three times sharper than what was previously possible.
What they found: the edges of solar granules — the Texas-sized convection cells of rising plasma — are not smooth at all. Instead, they are lined with innumerable small coils of plasma, each only 25 to 170 km long, separated by about 65 km.
Researchers identified them as Kelvin-Helmholtz instabilities — the same instability that curls ocean waves, clouds and Jupiter’s atmosphere. It occurs when two layers of fluid move past each other at different speeds, rolling up into vortices.
It is the first direct observation of this instability in the Sun’s photosphere, confirmed in a study published August 5 in the journal Nature by researchers from the US National Solar Observatory, Germany’s Max Planck Institute for Solar System Research, and the High Altitude Observatory.
The discovery could change how scientists understand energy transport. These whirlpools appear to be an efficient way to move energy and magnetic flux and could braid the Sun’s magnetic fields at small scales — a process that may help explain why the Sun’s outer atmosphere, or corona, reaches over 1 million degrees Celsius while the surface is just 5,500 degrees, and why solar storms that can disrupt satellites and power grids on Earth are triggered.
