Stunning Aurora Substorm Captured by Stargazers
Northern Lights brighten up the night sky and provide a beautiful sight during geomagnetic events. Many planets, including Earth, possess a magnetosphere — a vast magnetic shield generated by the planet's molten metal core. This shield extends deep into space and protects Earth from harmful charged particles by absorbing their energy upon contact.
How Geomagnetic Storms Occur
When regions of the magnetosphere become overloaded with energy, it can trigger a geomagnetic storm, similar to how thunderclouds build before a storm. During these storms, energy flows along Earth's magnetic field lines and plunges into the upper atmosphere, analogous to a heavy downpour.
The particle precipitation during geomagnetic storms injects millions of amps into the atmosphere, creating spectacular auroral displays far from the poles.
Solar Influence on Auroras
The Sun's magnetic storms sometimes eject massive amounts of solar material into space through explosive events. These eruptions, called coronal mass ejections (CMEs), manifest as enormous blobs traveling through the solar atmosphere.
Colors of the Aurora
Aurora colors arise from energetic particles colliding with gases in Earth's upper atmosphere. Each gas produces unique colors depending on the altitude where the collision occurs:
- Green: Most common, from oxygen gas excited at altitudes between 100–200 km.
- Blue: From nitrogen gas excited at 100–200 km altitude.
- Reddish-purple or pink: From nitrogen below 100 km altitude.
Summary
The interplay between Earth's magnetosphere and solar activity creates breathtaking auroral displays, with distinct colors visible depending on atmospheric gases and altitudes.