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In late April 2023, Earth experienced a powerful geomagnetic storm that lit up the skies with fascinating auroras, even at lower latitudes like Ladakh in India. These auroras are mostly restricted to the North Pole and northern regions of the world, but this geomagnetic storm was so powerful that it generated auroras that could be seen as far south as Ladakh. Now, Indian astronomers have traced the origins of this intense storm to the Sun. In particular, they used data collected from multiple space telescopes operating at different wavelengths.
Coronal mass ejections (CMEs), massive eruptions of ionized gas and the Sun’s magnetic fields, are known to trigger geomagnetic storms when they interact with the Earth’s magnetic field. These storms can have significant impacts on technology both on Earth and in space, making it crucial to understand and predict them.
The most intense geomagnetic storm of solar cycle 25 was caused by a large-scale CME eruption originating in ‘Active Region 13283’ near the center of the solar disk on April 21, 2023. Traveling at speeds of approximately 1500 km/s , the CME reached Earth. surrounding area on April 23, triggering the geomagnetic storm about an hour later. This storm peaked as a “severe G4” event, triggering stunning aurora displays captured by sky cameras at the Indian Astronomical Observatory in Ladakh, the Department of Science and Technology reported (summer schedule).
Researchers from the Indian Institute of Astrophysics, in a study published in The Astrophysical Journal, identified the solar source of this storm. Dr. P. Vemareddy, lead author, noted the unexpected intensity of the storm considering its launch from a region of relatively weak magnetic fields on the Sun.
Their analysis revealed that the rotation of the CME, influenced by magnetic forces, played a crucial role. The CME structure rotated approximately 56 degrees clockwise during its journey from the Sun to Earth, aligning its magnetic fields southward with respect to Earth’s magnetic field. This alignment facilitated effective interaction with the Earth’s magnetic field, which caused the intense geomagnetic storm.
The study highlights the importance of understanding the full picture of CMEs, including their magnetic structure and evolutionary mechanisms. With the launch of the Aditya-L1 space observatory, researchers hope to learn more about the behavior of CMEs. The Visible Emission Line Coronagraph (VELC) instrument on board Aditya-L1 will provide vital imaging observations close to the Sun, helping to better understand the dynamics of CMEs from their origin to their impact on Earth’s space environment.