Scientists discover faster rotation in the Sun’s upper atmosphere
By- Jyoti Rawat
The atmosphere whirling around the Sun spins at a much faster rate than the visible surface of the Sun and the rotation speed increase with height above the Sun’s surface, according to a new study that challenges the expectations of classical physics. Beyond improving our understanding of the Sun, these findings will help refine models of solar activity and space weather, which can affect satellites, communication systems, navigation networks, and power infrastructure on Earth.
For centuries, our culture has revered the Sun as Surya Dev, a symbol of life and energy. Yet, modern science continues to reveal that the Sun is far more complex than it appears. Like Earth, the Sun has an atmosphere, but scientists have long wondered how this vast atmosphere behaves as the Sun rotates.
Imagine an ice skater rotating at one point in the ice rink. When the skater pulls their arms close to their body, they spin faster, and when they stretch their arms outward, they slow down. This behaviour follows a fundamental law of physics called the conservation of angular momentum. Earth’s atmosphere generally follows this rule.
However, a new study by researchers from Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute under Department of Science and Technology (DST), Udaipur Solar Observatory (USO), Physical Research Laboratory (PRL), and Ahmednagar College found that Sun is not a stickler to this rule.
Using observations from the Nobeyama Radioheliograph in Japan, the team discovered that the Sun’s atmosphere rotates faster than its visible surface, breaking the rules of classical physics.
The study also found that the rotation speed increases with height above the Sun’s surface and decreases slightly when solar activity, indicated by the number of sunspots, becomes stronger. Conducted by Srinjana Routh and Vaibhav Pant (now at IIT Delhi) from ARIES, Anshu Kumari from USO-PRL, and Jaydeep Kandekar from Ahmednagar College, the research has been published in the journal Astronomy & Astrophysics Letters.
Since the Sun is made mostly of gas and has no solid land, it is very difficult to say whether it rotates similar to how the Earth does. So, to find how the Solar atmosphere rotates, a method known as “2D image-correlation method” was used, where the solar image of two separate days was cropped to similar ranges and compared with each other to see how much one image has shifted with respect to the other. That shift was then used to calculate the rotational velocity.
===============================================================
Publication Link: https://www.aanda.org/articles/aa/abs/2025/08/aa55364-25