Stunning Aurora Substorm Captured by Stargazers
The Northern Lights offer a breathtaking display to brighten the night sky. Many planets, including Earth, have a magnetosphere — a vast magnetic shield created by the planet's molten metal core that extends far into space.
Earth's magnetosphere protects the planet by absorbing energy from harmful charged particles in space. When certain regions of the magnetosphere accumulate too much energy, a geomagnetic storm can develop, similar to thunderclouds forming before a storm.
Geomagnetic Storms and Auroral Displays
During a geomagnetic storm, the built-up energy flows down Earth’s magnetic field lines and precipitates into the atmosphere like a heavy rain. This particle precipitation injects millions of amps of energy into the atmosphere, producing spectacular auroras visible far from the poles.
Solar Activity and Auroras
Occasionally, the Sun emits massive bursts of solar material through a series of explosive events called coronal mass ejections (CMEs). These enormous blobs travel through space and can trigger magnetic storms upon reaching Earth.
Colors of the Aurora
Aurora colors arise from energetic particles colliding with gases in the upper atmosphere, with each gas producing unique colors at different altitudes:
- Green auroras are the most common and occur when electrons excite oxygen gas between 100 and 200 km altitude.
- Blue auroras appear when nitrogen gas is excited at altitudes of 100 to 200 km.
- Below 100 km, nitrogen produces reddish-purple or pink glows.
"During a geomagnetic storm, accumulated energy flows down Earth's magnetic field lines and precipitates into the atmosphere like a heavy downpour."
Auroral displays remain a powerful reminder of the dynamic interaction between the Sun’s activity and Earth's magnetic environment.
Author’s summary: The aurora's brilliant colors result from charged particles interacting with Earth's atmosphere during geomagnetic storms triggered by solar activity.