Class sequence
A, B, C, M, and X are logarithmic decades of peak soft X-ray flux.
GOES soft X-rays · A through X
Solar Flares
See the latest GOES soft X-ray class and learn how A, B, C, M, and X flare classes differ from CMEs, geomagnetic storms, and radio-blackout scales.
Direct answer
The flare card classifies the latest GOES soft X-ray flux into A, B, C, M, or X with a multiplier. Each letter is ten times the previous threshold. A flare is not the same thing as a coronal mass ejection or geomagnetic storm.
Numeric multiplier
M5 is five times the M1 threshold; X2 is twice the X1 threshold.
Different phenomenon
A CME is an eruption of plasma and magnetic field; it may occur with a flare but is measured and forecast separately.
Physical space weather · refreshes hourly
The Sun–Earth Weather Dial
Current instrument readings with their observation time. No personal, medical, or spiritual state is inferred.
Kp is planetary context, not a local aurora forecast. GOES X-ray class is not a geomagnetic-storm forecast. Use the linked NOAA products for operational decisions.
What the GOES class means
Operational flare classes use peak 0.1–0.8 nanometer soft X-ray flux measured by GOES satellites. The class letter marks the power-of-ten band and the number gives the multiplier within it. This makes M2 stronger in X-rays than M1, while X1 begins the next decade above M-class. The live panel retains the subtype instead of reducing every reading to a vague letter.
Radiation arrives before particles or plasma
Electromagnetic radiation from a flare reaches Earth at light speed and can change the ionosphere on the sunlit side. Energetic particles and CME material travel more slowly and follow different paths. That timing difference is why a current flare classification cannot by itself tell you the Kp value expected later.
Radio blackouts and the R scale
NOAA’s R scale relates primarily to flare-associated X-ray effects on high-frequency radio on Earth’s sunlit side. It is separate from the G geomagnetic storm scale and S solar radiation storm scale. Use the official product for affected frequencies, areas, and timing rather than translating a flare class into an invented universal impact.
Flares, CMEs, and geomagnetic response
Some major flares accompany CMEs, but not every flare launches an Earth-directed CME and not every geomagnetic storm begins with an obvious large flare. CME speed, direction, density, and magnetic orientation influence coupling with Earth. Space-weather forecasters combine coronagraph, solar-wind, magnetic, and other observations.
Safe interpretation of the live value
The current X-ray class is useful factual context for radio and solar activity. It is not a direct measure of visible sunlight, weather, personal “energy,” or medical risk for a general reader at ground level. For aviation, satellite, radio, or infrastructure decisions, follow official alerts and organizational procedures.
Sources and live-data notes
- NOAA SWPC: GOES X-ray Flux ↗The GOES soft X-ray product used to classify current solar flare activity.
- NOAA SWPC: Space Weather Scales ↗Official R, S, and G scale meanings and impacts.
- NOAA SWPC: Planetary K-index ↗The planetary Kp product used by the Almanac space-weather endpoint.
- The Great Almanac live APISame-origin gateway for the latest NOAA-derived Kp and GOES X-ray reading.
Continue through the Sky & Time Almanac
Cluster hubSky & Time AlmanacAll observation guides, live instruments, and source boundaries.
NOAA observations · physical Sun–Earth systemSpace WeatherRead the current planetary Kp index and GOES X-ray class, then understand what NOAA space-weather scales do and do not say.
Magnetosphere · NOAA G scaleGeomagnetic StormsUnderstand NOAA’s G1–G5 geomagnetic storm scale, its Kp relationship, possible technology effects, and why current Kp is not a future local forecast.
Geomagnetic index · 0 to 9Kp IndexSee the current planetary Kp reading and understand its 0–9 scale, three-hour cadence, NOAA storm threshold, and limits for local aurora viewing.
Northern and southern lightsAuroraUse current Kp as context, then learn why aurora visibility requires an oval forecast, darkness, weather, geomagnetic latitude, and a clear horizon.
Common questions
Is an X-class flare ten times stronger than M-class?
The class thresholds differ by a factor of ten in peak soft X-ray flux. Numeric multipliers within each class also matter.
Does a solar flare cause aurora immediately?
Not usually. X-rays arrive in minutes, while aurora-producing geomagnetic disturbance often involves later solar-wind or CME interaction.
Is a flare the same as a CME?
No. A flare is a rapid release observed across electromagnetic wavelengths; a CME is an eruption of plasma and magnetic field. They can occur together or separately.
