Solar Flare
Definition
A sudden, intense burst of radiation from the Sun's surface, usually near sunspots.
In plain language
A flare is a flash of light and X-rays from a magnetically stressed region of the Sun. Flares themselves don't cause auroras, but they signal an active Sun and often accompany the eruptions (CMEs) that do.
The science
Flares are impulsive releases of magnetic energy via reconnection in the corona, classified by X-ray flux as A, B, C, M, or X class. Radiation reaches Earth in 8 minutes, causing radio blackouts on the dayside; associated CMEs, if Earth-directed, arrive 1โ3 days later.
Why it matters for aurora viewing
A big flare is a heads-up, not a guarantee โ check whether a CME was launched toward Earth before planning your night out.
See this in action on tonight's data.