Auroras (Polar Lights): Causes, Colours and the 2024-25 Storms

What an Aurora Is

The Chain From Sun to Sky

• Auroras are glowing curtains of light in the night sky. In the north they are called aurora borealis. In the south they are called aurora australis.
• The Sun constantly releases charged particles, called the solar wind. This wind strikes Earth’s magnetic field, and some particles get guided toward the polar regions. In the upper atmosphere, they hit gas atoms, and the collisions make the atoms glow. That glow is the aurora.
• Earth’s magnetic field creates a protective bubble in space, called the magnetosphere. It deflects most of the solar wind around the planet. The Sun squashes the bubble on the day side, and it stretches far behind Earth on the night side.

Why Near the Poles, and Where the Colour Comes From

• Magnetic field lines converge near the geomagnetic poles. Charged particles spiral down these lines and enter the atmosphere close to the poles. At the equator, the field lines stay nearly parallel to the ground.
• Auroras glow between roughly 80 and 300 km above the ground, in the upper atmosphere. The height strongly influences the colour.
• Oxygen gives the most common green colour, and at greater heights it also glows red. Nitrogen produces blue and purple, usually appearing lower in the display.

The 2024-25 Storms, and Why India Rarely Sees Them

The Solar Cycle and the May 2024 Mega Storm

• Solar activity rises and falls over about 11 years. At solar maximum, flares and storms become frequent, and auroras grow brighter and more common. Solar Cycle 25 peaked around 2024 to 2025.
• May 2024 brought the strongest geomagnetic storm in about 20 years, reaching G5, the top of the storm scale. Auroras appeared far beyond the polar regions, and people across Europe and North America photographed them.
• Auroras form rings around each geomagnetic pole, called auroral ovals. These ovals usually sit between about 65 and 75 degrees of geomagnetic latitude, but strong storms push them toward the equator.

Why India Rarely Sees Them, and the Grid-and-Satellite Risk

• India lies at a low geomagnetic latitude, so the auroral ovals stay far to the north and south. Extreme storms can stretch them toward India. In April 2023, rare auroras were photographed from Ladakh.
• Auroras are the visible face of geomagnetic storms. The same storms can disturb power grids and satellites. Scientists watch the Sun to forecast them, since the lights are beautiful but also part of a warning system.
• Jupiter has the strongest magnetic field of any planet, and its auroras are the most powerful in the solar system. Saturn also glows with polar auroras, mostly ultraviolet light.