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A century of geomagnetic storms

Earth's geomagnetic activity, logged every three hours since 1932 as the Kp index and drawn as the swing of a compass needle. Quiet years barely move it; the Sun's 11-year cycle breathes underneath; the biggest storms — 1989, 2003, 2024 — push the needle to the pin and light the sky with aurora.

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Jump to the great storms

Data & source

Source: the planetary Kp / ap index from GFZ Helmholtz Centre Potsdam · CC BY 4.0 · fetched —. Kp is a quasi-logarithmic 0–9 index of geomagnetic disturbance derived from 13 subauroral magnetometers, published every three hours since 1 January 1932; here each day is its strongest three-hour Kp. The needle and aurora are a stylized instrument — deflection and the green glow are driven by that day's peak Kp and exaggerated to be visible, not a literal compass reading or a forecast of where aurora was seen. Storm level is the NOAA G-scale (G1 = Kp 5 … G5 = Kp 9). The named storms below are documented events; their Kp is read from this file.