First time here?
This site is a photo-book about the northern lights, kept live. Four things are enough to read it: what Kp means, how tonight's verdict is made, where the map sends you, and when to go. Each block below lifts the site's own definition and opens one door.
What Kp means
“A general index used in aurora forecasting, graded from 0 to 9. The ‘K’ index measures variations in the Earth's magnetic field. 0–1 is calmest; 5 and above means a geomagnetic storm.”
Kp measures geomagnetic activity from 0 (calm) to 9 (extreme storm). The live number at the top of every page is this index, read from NOAA a few minutes ago.
● The book's Kp spread — how to read it →How tonight's verdict is made
The forecast reads three things at once: the live Kp against what your spot needs, whether it is truly dark there tonight, and the cloud. Then it says it plainly — go, maybe, or not tonight.
“The clearest Kp is useless under cloud; a bright moon washes the sky out too.”
Activity peaks around magnetic midnight — though it can break out any time.
● Tonight's forecast →Where the map sends you
“The auroral oval widens and pushes equatorward as a storm grows.”
The atlas shows the auroral oval over the places the book stood and the watch points the site tracks. Every one of them has its own page: the Kp it needs, tonight's verdict, and twelve months of real cloud climatology.
● The atlas →When to go
“The solar cycle raises and lowers sunspots; near maximum the aurora reaches further south.”
Aurora needs true darkness, so the season runs from autumn to spring at these latitudes. The calendar shows the dark, moonless weeks night by night; the trip planner turns a single sentence into computed odds.