Drag the class slider to step through the GOES flare scale from quiet (A) to extreme (X20) and watch the flare loop, the particle burst, and the radio-blackout reach on the Earth companion scale with it.
Whenever a bright kink flares up on the Sun's disk, NOAA's GOES satellites are already measuring how bright it is in soft X-rays and sorting it into a letter class. Slide through A, B, C, M, and X here to see why an M5 triggers a NOAA alert while an X20 blacks out high-frequency radio across the whole sunlit side of Earth.
Drag to orbit and scroll or pinch to zoom. For the plasma cloud a strong flare can throw outward, see the Coronal Mass Ejection 3D Explorer; for the sunspot count this activity rides on top of, see the Sunspot Activity 3D Explorer.
Solar Flare Classification 3D Explorer
This browser explorer visualizes the GOES X-ray flare classification scale - the letter-and-number system NOAA uses to rate how strong a solar flare is, and the matching NOAA Radio Blackout (R) scale that describes what a flare of that strength does to high-frequency radio on Earth.
GOES satellites measure the Sun's peak soft X-ray output in the 1-8 angstrom band and sort each flare into a letter class, each one a power-of-ten step: A is below 1e-7 W/m^2, B is 1e-7 to below 1e-6 W/m^2, C is 1e-6 to below 1e-5 W/m^2, M is 1e-5 to below 1e-4 W/m^2, and X is 1e-4 W/m^2 or higher, with no formal upper cap. Each letter subdivides linearly from 1.0 to 9.9 - an M5 flare is 5x10^-5 W/m^2, an X1 flare is 1x10^-4 W/m^2. NOAA's 5-level Radio Blackout scale ties directly to these classes: R1 (Minor) starts at M1, R2 (Moderate) at M5 - the level at which NOAA's Space Weather Prediction Center issues an alert - R3 (Strong) at X1, R4 (Severe) at X10, and R5 (Extreme) at X20. The largest confirmed flare on record is the X28 flare of 4 November 2003, part of the "Halloween storms" - the GOES sensor saturated near its peak, so the true value may have been even higher.
- Drag the flare-class slider to step through A, B, C, M1, M5, X1, X10, and X20
- Watch the flare loop brighten and the particle burst intensify as the class rises
- Watch the red reach arc on the Earth companion grow once a class reaches M1/R1 or higher - classes A through C carry no NOAA Radio Blackout rating at all
- Drag to orbit, scroll or pinch to zoom
- Runs fully in the browser with the vendored three.js engine - no account, no upload
| Class | Peak X-ray flux (1-8 angstrom) | NOAA Radio Blackout rating |
|---|---|---|
| A | below 1e-7 W/m^2 | none |
| B | 1e-7 to below 1e-6 W/m^2 | none |
| C | 1e-6 to below 1e-5 W/m^2 | none |
| M1 | 1e-5 W/m^2 | R1 - Minor |
| M5 | 5e-5 W/m^2 | R2 - Moderate (NOAA alert level) |
| X1 | 1e-4 W/m^2 | R3 - Strong |
| X10 | 1e-3 W/m^2 | R4 - Severe |
| X20 | 2e-3 W/m^2 | R5 - Extreme |
For the plasma cloud a strong flare can throw outward, open the Coronal Mass Ejection 3D Explorer; for the 11-year rise and fall in sunspot counts this activity rides on top of, open the Sunspot Activity 3D Explorer.
Everything renders on your device with WebGL. The 3D engine loads once (about 0.7 MB) and is cached.
This is an educational approximation, not a physical simulation. Flare brightness, loop size, particle-burst intensity, and the Earth companion's reach arc are scaled for visibility and are not a rendered radiative-transfer or magnetic-reconnection model, and the reach arc is not a precise blackout footprint map. The flux ranges and R-scale figures above are the real NOAA SWPC ones.
Frequently Asked Questions
What do the A, B, C, M, and X letters mean?
They are GOES flare classes based on the Sun's peak soft X-ray flux in the 1-8 angstrom band: A is below 1e-7 W/m^2, B is 1e-7 to below 1e-6, C is 1e-6 to below 1e-5, M is 1e-5 to below 1e-4, and X is 1e-4 W/m^2 or higher, with no formal upper cap.
What does the number after the letter mean?
Each letter class subdivides linearly from 1.0 to 9.9. An M5 flare is 5x10^-5 W/m^2; an X1 flare is 1x10^-4 W/m^2; an X20 flare is 2x10^-3 W/m^2.
What is the NOAA Radio Blackout (R) scale?
It is NOAA's 5-level scale for how a flare of a given class disrupts high-frequency radio on Earth's sunlit side: R1 (Minor) starts at M1, R2 (Moderate) at M5, R3 (Strong) at X1, R4 (Severe) at X10, and R5 (Extreme) at X20. Classes A through C carry no Radio Blackout rating.
At what class does NOAA issue an alert?
NOAA's Space Weather Prediction Center issues an alert once a flare reaches M5 (R2 - Moderate).
What is the biggest solar flare ever recorded?
The largest confirmed flare on record is the X28 flare of 4 November 2003, part of the "Halloween storms". The GOES sensor saturated near its peak, so the true value may have been even higher.
Is the flare animation showing the real brightness and speed?
No. The flare loop's size and glow, the particle-burst intensity, and the Earth companion's reach arc are scaled for visibility, not rendered from a radiative-transfer or magnetic-reconnection model. The flux ranges and R-scale figures in the facts panel are the real NOAA SWPC ones.
How is this different from the Coronal Mass Ejection page?
A coronal mass ejection is the plasma cloud a flare can throw outward, tracked as it travels; this page is the X-ray brightness classification scale for the flare itself, which can happen with or without an accompanying ejection.