Earth's magnetic mood, 94 years on one spiral.
The Kp-index measures how strongly the Earth's magnetic field is shaking under the solar wind, every three hours, on a scale from 0 to 9. Below 5 the night sky is quiet. From 5 upward the auroras start drifting south. The 11-year solar cycle turns this index into a steady pulse — which is hard to see in a table and easy to see when you wind the timeline into a spiral.
Where the needle sits this second.
The gauge reads the latest three-hour Kp value from NOAA's Space Weather Prediction Center. Colour zones mark the five storm thresholds — G1 at 5, G5 at 9. Most of the time the needle stays in the cool zone, but during the 2024 May storm it sat at the right edge for almost two days.
If your browser blocks NOAA's CORS-free public endpoint, the gauge falls back to the latest daily maximum from the GFZ archive. The visual reading is the same — the source line changes.
Wind the timeline into a circle.
Each ring is one year, starting in 1932 at the centre and spiralling out to today. The twelve months mark like a clock — January at the top, June at the bottom. Each five-day segment is coloured by the worst Kp value in that window. The 11-year solar cycle becomes a slow heartbeat of red around the outer rings, fading to quiet blue between maxima.
Hover any segment for the year, the day and the Kp value. The yellow dots on the January spoke mark the eight known solar maxima since 1932 — they sit on the spiral like beats of a drum, separated by roughly eleven years. Five-day binning keeps the spiral readable without losing the storms.
When the spiral burned red.
Four geomagnetic storms that stood out by a wide margin. Carrington in 1859 is the historical benchmark — measured before the Kp scale existed but reconstructed from contemporary records. The other three sit clearly visible on the spiral, three of the deepest reds in the outer rings.
The Carrington Event
The benchmark of the modern era, named after the British astronomer Richard Carrington who saw the solar flare from his observatory in Surrey. The induced currents lit telegraph paper on fire in some offices and let operators send messages without batteries. Reconstructed Kp from the literature: 9.
Aurora visible as far south as Cuba, Honolulu, and the Caribbean. A modern repeat would knock out a third of the world's power transformers.
Quebec Blackout
The first geomagnetic storm that took down a modern power grid. Within 92 seconds, the Hydro-Québec network collapsed and left six million people without electricity for nine hours in the middle of a Canadian winter. Transformers were damaged from New Jersey to Sweden.
Aurora reported from Florida and Cuba. After 1989 grid operators began modelling geomagnetically induced currents for the first time.
The Halloween Storms
A week of back-to-back X-class solar flares. The SOHO satellite went offline temporarily, a Japanese satellite was lost, and astronauts on the ISS sheltered in shielded modules. Sweden lost power in Malmö for an hour. Kp pegged 9 multiple times.
Aurora visible from Texas, Florida and the Mediterranean. Several spacecraft permanently damaged. The last G5 of the third millennium until 2024.
The Gannon Storm
The first G5 in twenty years, named in memory of NOAA forecaster Jennifer Gannon. Five coronal mass ejections collided into Earth's magnetosphere over a weekend. Aurora photographed from Mexico and the Bahamas. SpaceX reported degraded performance on most of its Starlink satellites for several days.
Aurora seen across the contiguous United States and as far south as Puerto Rico. Farming GPS receivers across the US Midwest lost their fix during planting season.
G5 means "extreme", the top of the NOAA storm scale. A G5 in a densely electrified world looks different than a G5 in 1859 — the same magnetic disturbance now hits power grids, satellites and pipelines built around the assumption that days like these are rare.
Eight solar maxima since 1932. They line up on the spiral like beats of a slow drum.
Data: GFZ Helmholtz Centre, Geomagnetic Observatory Niemegk · Kp index since 1932-01-01, three-hourly · Matzka et al. 2021, CC BY 4.0 · Live value: NOAA SWPC planetary_k_index_1m.json · Daily aggregate: maximum Kp per day, then binned into five-day arcs on the spiral