Basics

The science

Coronal Holes and Recurrent Geomagnetic Storms

Coronal holes drive steady, predictable geomagnetic storms that recur roughly every 27 days -- how they form and why that cadence matters.

Do Aurora Affect Power Grids? Geomagnetically Induced Currents Explained

Geomagnetic storms can induce real currents in power grids and pipelines. Here is the rate-of-change threshold that matters and how seriously to take it.

How to Read a Solar Wind Plot: Bz, Bt, Speed and Density

Every aurora forecast comes down to four numbers -- Bz, Bt, speed and density. Which one to watch first, and how to read them together.

Solar Cycle 25, Solar Cycle 26, and What They Mean for Aurora Chasers

The Sun's roughly 11-year activity cycle drives how often strong aurora happens. Where Solar Cycle 25 stands now and what comes next.

STEVE, Airglow, and Other Things That Are Not the Aurora

Not every glowing ribbon in the night sky is the aurora. How to tell the real thing apart from STEVE, airglow, and satellite trains.

Substorms Explained: Why the Aurora Suddenly Erupts

The sudden brightening that makes for a memorable aurora display has a name: a substorm. What actually happens during one, physically.

What Is a CME? Coronal Mass Ejections Explained

Coronal mass ejections drive the biggest geomagnetic storms and aurora displays. What they are, how they travel, and why timing them is hard.

Why Is the Aurora Green, Red and Pink? The Physics of Aurora Colour

Aurora colour comes down to which gas is glowing and at what altitude. The atomic physics behind green, red and pink displays, plainly explained.

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