Great American Eclipse: Indian scientists’ prediction on magnetic field, sun’s corona comes true
Indian solar scientists said images of the total solar eclipse closely correlate with predictions on the structure of the corona – the halo of the sun – and underlying magnetic fieldmumbai Updated: Aug 24, 2017 11:36 IST
The great American solar eclipse that crossed the entire US continent for the first time in 99 years on August 21 has given India reasons to cheer.
Indian solar scientists said images of the total solar eclipse closely correlate with predictions on the structure of the corona – the halo of the sun – and underlying magnetic field. Knowing the magnetic field structure in the corona will help Indian scientists to predict space weather, and solar storms that can affect the earth’s magnetosphere where many satellites such as telecommunication, GPS navigation are located.
“The correlation means the Indian group has got the main structure of the corona and the underlying magnetic field right. This doesn’t mean that the structure of the plumes of the corona that releases charged particles has to be exact. What’s important is where in the sun they are coming out from and their appearance,” said Somak Raychaudhary, director, Inter-Universty Centre for Astronomy and Astrophysics, Pune, told HT.
Apart from the Centre for Excellence in Space Sciences India (CESSI) at the Indian Institutes of Science Education and Research, Kolkata (IISER-K), the only other group that made predictions is US-based Predictive Sciences Inc. “Even though the images don’t match line by line, what is important is to get the basic outlay correct. Results from the India group are better than the US group,” said Raychaudhary.
Refusing to comment on the outcome of their predictions, the CESSI team said, “We are encouraged by the results.”
With this, India’s homegrown effort to build indigenous space weather prediction models and make technologies safe in space has got a fillip. At present, India relies on calculation and models provided by international space agencies particularly NASA.
These results will also help when India sends its first satellite to study the sun – Aditya L1 – scheduled for 2020. “We can make operational space weather forecasting from India, and use these computer models to understand what is being seen by the satellite. Most importantly, we won’t need to depend on foreign countries to make our technologies safe in space,” said a scientist involved in the mission.
Based on computer modelling and simulations, scientists at CESSI had on August 18 predicted four flower petal like structures in the southern and northern hemispheres of the sun.
- The lotus petal-like structure on the lower-left edge of the sun (as viewed from the earth) was closer to the Sun’s equator than predicted. However, the team’s prediction that the upper-left edge of the Sun will be the least active was correct.
- The lotus petal-like structure on the lower-right edge of the sun (as viewed from the earth) was correct.
- A third, narrow elongated lotus petal-like structure on the upper-right edge of the sun was correct.
- “These predictions have all been largely verified”, said Niruj Mohan, Chair of the Astronomy Society of India’s Committee on Public Outreach and Education.
Before predicting, the team ensured all the observed features of the sun were fed into their indigenous models before forward-running them to August 21.
“We are new kids on the block, and therefore not expecting everything to be right,” said Dibyendu Nandi, CESSI and department of physical sciences, IISER-K, who heads the team. “About two weeks we felt our models were ready to be tested with the observation of the eclipse. These models have to be run with some observational data, and therefore predictions made too far back in time can go wrong because the observed magnetic structures of the sun change too much.”
The sun’s corona and the underlying magnetic field structures is important primarily because they determine the environment in space and around the earth, particularly solar storms. These solar storms which originate in the corona’s magnetic field carry large amounts of charged particles and move towards inter-planetary space. “They can sometimes come towards the earth, and hit our outer environment called magnetosphere that has a lot of satellites including those from India,” said Nandi.
Many modern day technologies including telecommunication, GPS navigation satellites, electric power grids, air-traffic on polar routes are dependent on space-reliant technologies and satellite operations are affected and impacted by solar storms.
“With technology parked in space, we need to have scientific ways either through theoretical models or observation of the sun to predict solar storms and space weather,” said Nandi, also associate at the Inter-University Centre for Astronomy and Astrophysics, Pune.
It was in early 2016 that the IISER-K team in collaboration with Durham University, UK, started working on theoretical models to predict space-weather based on the modelling of solar magnetic fields. The August 21 solar eclipse provided a very good opportunity to test and refine the computer models that have been built for the sun to predict the storms.
On regular days, one cannot see the corona very well because the disc of the sun is much brighter, and the corona is very faint because it is low density gas. During an eclipse, however, the bright disc is blocked out and good telescopes help in seeing the corona.
Both the US and India-UK teams predicted flower petal-like structures in the left and right side of the southern hemisphere of the sun’s corona, with only a slight difference in the location of the structures. “Theirs is close to the equator; ours slightly higher in the latitude towards the pole,” said Nandi.
The Indian team solely predicted another structure on the right side of the northern hemisphere. On the left side, their models saw a more diffused structure.
“So we predicted some magnetic field structures in all the quadrants – left and right of both southern and northern hemispheres. For the US team, only two petals on the left and right side of the southern hemisphere is more prominent,” said Nandi.
First Published: Aug 22, 2017 15:25 IST