Why total solar eclipse is important to global scientific community
A total solar eclipse is an ideal opportunity to study the Sun under conditions impossible at any other time, as the crisp lunar shadow reveals the corona’s inner and middle parts in visible lightUpdated: Aug 21, 2017 16:01 IST
Skywatchers are in for a treat when the Moon passes in front of the Sun and the lunar shadow races diagonally across the US in the first total solar eclipse there in 99 years.
No such luck for those in India though who have to be content with watching the spectacular event live-streamed. (The next total solar eclipse in India will be in 2034.) India’s own solar probe, Aditya, is scheduled to be launched in 2020. Nevertheless, Indian scientists will be thrilled to share the data collected by their colleagues in the United States and elsewhere who plan several experiments during totality, when the Moon covers the Sun’s disc completely, revealing the outermost layer of the Sun, or corona.
A total solar eclipse is an ideal opportunity to study the Sun under conditions impossible at any other time, as the crisp lunar shadow reveals the corona’s inner and middle parts in visible light. Ground-based observations along with satellite data offer the most complete view of the Sun’s atmosphere ever seen.
Of particular interest to astronomers will be sunspots: Regions of intense magnetic activity on the Sun’s surface where energy flow from the interior is reduced by strong magnetic fields, making them ‘cool’ at about 1,500 degrees — relatively ‘darker’ than their surroundings at 6,000 degrees. It’s still a mystery why sunspots peak every 11 years — at ‘solar maximum’ — when solar flares and coronal mass ejections (CMEs) explosively emit billions of tons of electrically charged particles from the Sun’s outermost layer.
Despite a number of satellites in orbit to study the Sun, astronomers have yet to figure out how radiation builds up as CMEs and is spewed Earthwards. The CME storms sometimes slam into Earth’s atmosphere and interact with its magnetic field. Once Earth’s field is sufficiently weakened, these particles create geomagnetic storms that disrupt electrical and communications systems, with current surges in power lines and cables. The midway point for the current sunspot cycle was 2016, so this eclipse offers the last opportunity to study the remaining sunspots as the ‘solar minimum’ approaches.
Another mystery that scientists would try to solve is the strange migration pattern of sunspots from the Sun’s north and south latitudes towards its ‘equator’ which, on a map, looks like the wings of a butterfly. This butterfly movement holds the key to one of the major mysteries in solar physics: The solar ‘dynamo’, which converts mechanical motions on the Sun into magnetic energy.
The minutes of totality also give scientists an excellent opportunity to measure the temperature of Mercury, the closest planet to the Sun. With the Sun hidden, Mercury can be studied in infrared light (which is used to measure the temperature of objects that are not hot enough to radiate light).
And while the darkness lasts, scientists could even search for Vulcanoids, hypothetical objects left over from the beginning of the solar system. These are believed to be hiding in plain sight, travelling inside Mercury’s orbit and evading discovery in the glare of our parent star.
Prakash Chandra is a science writer
The views expressed are personal