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

The northern and southern lights are one phenomenon wearing two names. They are the sky’s visible answer to storms on the Sun.

Aurora borealis over Eielson Air Force Base, Alaska. Public domain (U.S. Air Force), via Wikimedia Commons.

📑 Contents

✅ Must Know

What an Aurora Is

Names 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 Chain of Cause

Solar Wind The Sun constantly releases charged particles. This outward flow is called the solar wind. The wind strikes Earth’s magnetic field. Some particles get guided toward the polar regions.
Collision In the upper atmosphere the particles hit gas atoms. The collisions make the atoms glow. That glow is the aurora.

The Magnetosphere

Magnetic Shield Earth’s magnetic field creates a protective bubble in space. Scientists call it the magnetosphere. It deflects most of the solar wind around the planet.
Shape The Sun squashes the bubble on the day side. It stretches far behind Earth on the night side.

Why Near the Poles

Field Lines Magnetic field lines converge near the geomagnetic poles. Charged particles spiral down these lines. They enter the atmosphere close to the poles. At the equator the field lines stay nearly parallel to the ground.

Where the Light Comes From

Glowing Atoms The incoming particles excite oxygen and nitrogen atoms. The excited atoms release the extra energy as light. The result is like a giant neon tube in the sky.

How High Up

Altitude Auroras glow between roughly 80 and 300 km above the ground. This places them in the upper atmosphere. The height strongly influences the colour.

Good to Know

📘 Good to Know

Which Gas Makes Which Colour

Oxygen Oxygen gives the most common green colour. At greater heights it also glows red.
Nitrogen Nitrogen produces blue and purple. These colours usually appear lower in the display.
Height Green comes from oxygen about 100 km up. Red comes from oxygen higher still. Blue and purple come from nitrogen lower down.

The Auroral Oval

Ring Auroras form rings around each geomagnetic pole. These rings are called auroral ovals.
Latitude The ovals usually sit between about 65 and 75 degrees of geomagnetic latitude. Strong storms push them toward the equator.

The 11-Year Solar Cycle

Sunspot Cycle Solar activity rises and falls over about 11 years. At solar maximum, flares and storms become frequent. Auroras grow brighter and more common. Solar Cycle 25 peaked around 2024 to 2025.

What the Names Mean

Roman Roots Aurora was the Roman goddess of dawn. Boreas was the north wind. Auster was the south wind. The names mean ‘northern dawn’ and ‘southern dawn’.

📝 Previous Year Questions

UPSC CSP 2022 — A Solar Storm’s Effects

UPSC 2022 UPSC Prelims 2022 asked which effects a major solar storm can have on Earth. Intense auroras were one correct effect. So were damaged power grids and disturbed satellite orbits. Asked as: “If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth?” (UPSC CSP 2022, GS Paper I).

UPSC CSM 2024 — The Two Auroras

UPSC 2024 UPSC Mains 2024 asked what aurora australis and aurora borealis are. It also asked how they are triggered. This 15-mark Geography question appeared in GS Paper I. Asked as: “What are aurora australis and aurora borealis? How are these triggered?”

🌟 Great to Know

Auroras Beyond Earth

Jupiter Jupiter has the strongest magnetic field of any planet. Its auroras are the most powerful in the solar system.
Saturn Saturn also glows with polar auroras. Their light is mostly ultraviolet.

The May 2024 Mega Storm

G5 Storm May 2024 brought the strongest geomagnetic storm in about 20 years. It reached G5, the top of the storm scale. Auroras appeared far beyond the polar regions. People across Europe and North America photographed them.

Why India Rarely Sees Them

Geomagnetic Latitude India lies at a low geomagnetic latitude. 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 Space Weather

Solar Connection Auroras are the visible face of geomagnetic storms. The same storms can disturb power grids and satellites. Scientists watch the Sun to forecast them. The lights are beautiful, but they are also a warning system.

📚 Related Articles