Pariksha SaathiARIES-Led Study Links the Sun's Bright Microwave Poles to Its Polar Magnetic Field and Coronal Holes
When the Sun is observed at certain microwave and radio frequencies, its polar regions appear brighter than the rest of the disc — an effect called microwave polar brightening, whose cause had remained unclear. A team of Indian researchers has now traced it to magnetic activity at both large and small scales, the Department of Science and Technology said on 12 October 2026. The study was a collaboration between the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, an autonomous institute under DST; the Udaipur Solar Observatory of the Physical Research Laboratory; IIT Delhi; and IIT Roorkee. Using almost thirty years of 17 GHz data from Japan's Nobeyama Radioheliograph, combined with NASA Solar Dynamics Observatory images and Wilcox Solar Observatory magnetic measurements, the team found that the polar brightening rises and falls with the size of polar coronal holes and, even more closely, with the strength of the Sun's polar magnetic field. Individual bright patches often matched coronal bright points and coronal jets. The northern and southern poles also behaved differently over the long term. The findings, which appeared in The Astrophysical Journal, may improve understanding of the Sun's polar environment and of where the solar wind comes from.
Drafted with AI assistance from the official PIB release linked above and checked against it by a second AI pass. Not line-edited by a human.
Learning context
ARIES, headquartered at Manora Peak, Nainital, began life as the Uttar Pradesh State Observatory, which started functioning at Varanasi on 20 April 1954. After Uttarakhand’s creation in 2000, it briefly became the ‘State Observatory’, before being renamed the Aryabhatta Research Institute of Observational Sciences (ARIES) on 22 March 2004, when it became an autonomous institute under the Department of Science and Technology, Government of India.
Reference: ARIES official website (history)
Check yourself: has ARIES always been called by that name since its founding?
No — it was founded in 1954 as the Uttar Pradesh State Observatory; the ARIES name and its status as a DST autonomous institute date only from 2004, exactly 50 years later.
Revision task: separate today’s specific finding (the Sun’s microwave-bright poles linked to coronal holes) from this standing fact about the institute that led the study.
Test yourself
A study led by ARIES, Nainital, linked the Sun's 'microwave polar brightening' most closely to what?
Show the answer
Answer: The strength of the Sun's polar magnetic field
Using almost thirty years of 17 GHz Nobeyama Radioheliograph data, the team found that the polar brightening tracks the size of polar coronal holes and, even more closely, the strength of the polar magnetic field; ARIES is an autonomous institute under the Department of Science and Technology.
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