Space weather and aurora forecast: track solar flares, CMEs, and the Kp index live.
The Sun is not quiet. It throws flares of radiation, hurls coronal mass ejections across the solar system, and stirs up geomagnetic storms that paint the sky with aurora and, in strong cases, disrupt satellites, radio, and power grids. Lumara shows all of it live, pulled from NASA's space weather database, free and with no account.
The three things space weather tracks.
Space weather sounds abstract, but it comes down to three measurable events, and Lumara surfaces all three:
- Solar flares: sudden bursts of radiation from the Sun, rated by X-ray brightness in classes B, C, M, and X.
- Coronal mass ejections (CMEs): clouds of plasma and magnetic field launched into space, sometimes aimed at Earth, traveling at up to about 3,000 km/s.
- Geomagnetic storms: disturbances in Earth's magnetic field caused by CMEs and fast solar wind, measured by the Kp index from 0 to 9 and the G1 to G5 storm scale.
Can you see the northern lights tonight?
Most of the time, aurora visibility comes down to one number: the Kp index. The higher it climbs, the farther from the poles the aurora reaches. Your latitude decides how high the Kp needs to be for you.
| Kp index | Storm level | Where aurora may be visible |
|---|---|---|
| 0 to 3 | Quiet | High latitudes near the poles only |
| 4 | Active | Far northern latitudes, dark skies |
| 5 | G1 minor storm | Northern tier of US states, northern Europe |
| 6 to 7 | G2 to G3 | Pushes toward mid latitudes |
| 8 to 9 | G4 to G5 | Rare strong storms, aurora possible far south |
Lumara shows the current Kp index and recent geomagnetic activity in real time, so you can check conditions before you drive somewhere dark. Clear skies and distance from city light matter as much as the number.
Solar flare classes, explained.
Solar flares are graded by their peak X-ray output. Each class is ten times more intense than the one below it.
| Class | What it means |
|---|---|
| B | Background level. Minor, no real effect on Earth. |
| C | Small. Few noticeable effects at the surface. |
| M | Medium. Can cause brief radio blackouts near the poles and minor radiation storms. |
| X | The strongest. Can trigger planet-wide radio blackouts, and with a CME, major geomagnetic storms. |
Lumara labels the latest flare by class, so you can tell at a glance whether the Sun is calm or active without reading a forecast bulletin.
How Lumara tracks space weather.
Lumara pulls live data from NASA's DONKI feed, the Database Of Notifications, Knowledge, Information that space weather forecasters use. It shows recent flares, CMEs with their speed, and the current geomagnetic storm level, updated in real time. There is no account, no ads, and no tracking of any kind. The app is free on Google Play (Android 8.0 and up) and the App Store (iOS 14.0 and up, universal iPhone and iPad).
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Common questions.
What is the Kp index? A 0 to 9 scale of geomagnetic activity measured over three-hour windows. Low is quiet, high means a storm is underway and aurora reaches lower latitudes.
What Kp do I need to see aurora? It depends on your latitude. Kp 5 often brings aurora to the northern tier of US states. Kp 7 or higher can reach mid latitudes. Near the poles, Kp 3 or 4 may be enough.
What is a CME? A coronal mass ejection: a cloud of plasma and magnetic field thrown from the Sun. An Earth-directed CME can spark a geomagnetic storm a day or two later.
Is the data free? Yes. Lumara is free on both stores, and the space weather data comes from NASA's public DONKI feed.