Great American solar eclipse: Studying the Sun’s corona

IISER Kolkata and scientists across the world are trying to use the eclipse to verify their theories.

Synthetic coronal structure prediction of the August 21, 2017 “great American Solar eclipse”. Photo courtesy: CESSI/IISER

A solar eclipse is set to take place, which will be visible across all of continental United States. It will begin at the Oregon coast (at 9.36 p.m. IST on August 21, 2017) and end at the South Carolina coast (at a time that corresponds to 1.36 a.m. IST on August 22, 2017). About 16% of the U.S. will witness a total eclipse, which will last longest at Carbondale, Illinois, for 2 minutes and 41.6 seconds. Since this eclipse has the special feature of lasting for so long over the mainland, scientists across the world are trying to use it to verify their theories on the Sun. This can help them model “space weather” and predict solar storms that can affect the operation of satellites and even electric power grids on Earth.

 

Computer simulations

Predicted magnetic field structure of the Sun’s corona of the August 21, 2017 “great American solar eclipse”. Photo courtesy: CESSI/IISER

 

The “great American solar eclipse,” as it is being dubbed, is keeping scientists at the Centre for Excellence in Space Sciences India (CESSI) in the Indian Institutes of Science Education and Research (IISER), Kolkata, busy even before it begins. Using computer simulations, they have predicted the shape that the outer layer of the Sun — its corona — will take during the total eclipse. If their prediction is correct, their model of the Sun will be validated and they can then fine-tune it to make predictions of space weather, for one, which is CESSI’s eventual mandate.

Space weather impacts modern day technologies such as satellite operations, telecommunications, GPS navigational networks and electric power grids. So, astronomical events such as an eclipse, which offers a chance of diagnosing the coronal magnetic field, are an opportunity for solar physicists to test their theoretical ideas and models to be able to refine them.

Verifying theories

“Once the event takes place, they [the research groups] can judge how close to reality they are and even if they are not close, they can go back to the drawing board and refine their theories,” said Niruj Mohan Ramanujam, Chairperson of the Public Outreach and Education Committee of the Astronomical Society of India.