The Gauribidanur IIA observatory measures magnetic fields in the solar corona

A team of radio astronomers and engineers from the Indian Institute of Astrophysics (IIA) has successfully demonstrated unequivocal measurements of magnetic fields in the Sun’s corona, located 150 million kilometers away.

The measurements were made using a unique and sensitive radio telescope system set up at the IIA Gauribidanur Observatory.

The radio telescope is made inside the Gauribidanur observatory using raw materials available in the country.

The team picked up the twisting of electromagnetic radio waves from the “undisturbed” Sun, called polarization, with their telescope.

What causes twisting

The twist is caused by the magnetic field. The measured degree of polarization is very small, approximately 0.01 to 0.02, and these are the first ever reported direct measurements of this type.

According to Shaik Sayuf, a PhD student at the IIA who observed and analyzed the data, the associated magnetic field strengths are less than one-thousandth of a Tesla, the basic unit of measurement for magnetic field strength.

Mr. Sayuf’s PhD supervisor at the IIA, C. Kathiravan, said: “The estimated field strengths are similar to those produced by bar magnets in school laboratory experiments. Interestingly, similar small field strengths in the Sun’s atmosphere can cause powerful eruptions that create near-Earth disturbances and affect the functioning of satellites.”

R. Ramesh, IIA senior professor and head of IIA radio astronomy activities at Gauribidanur Observatory, said that it is currently almost impossible to make similar measurements of the magnetic field in the solar corona with ground-based or space-based telescopes that operate in other wavelength bands of the electromagnetic spectrum.

Training ground

Mr. Ramesh added that the results show how the Gauribidanur observatory is being effectively used as a training ground to provide valuable hands-on experience to students and a testbed for the development of new technologies in radio astronomy with minimal investment compared to major ground-based and space-based observatories elsewhere.

Published – 02 Jun 2026 21:57 IST