SUN
The Sun: flares, solar wind and impacts on Earth.Solar activity and its measured impacts.
Here you can find NOAA measurements, an explanation of their possible impacts on Earth and images of the Sun from NASA/SDO.NOAA measurements for the R, S and G scales, solar wind and NASA/SDO images.
Solar activity measurements from NOAA.
Read the impacts separately
Aurora
We assess the northern lights using magnetic activity and conditions in Czechia. Open the outlook ↗
SIMULATION FOR YOUR PLACE
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Ultraviolet channels are shown in false colour.
Verified region positions are not available yet. An empty disc does not mean there is nothing on the Sun.
All regions
SUN → EARTH
Three messengers from the Sun
Each travels at a different speed. A strong flare alone does not imply an aurora.
Last measured on . Conditions may have changed since then.
Solar activity at this measurement was quiet.
- Geomagnetic storm
- no reported impact (G0 of 5)
- Radio blackouts
- no reported impact (R0 of 5)
- Radiation storm
- no reported impact (S0 of 5)
- Flares
- weak, class B3.8
- Solar wind speed
- slow flow, 370 km/s
NOAA SWPC
SOLAR X-RAY EMISSION
Minute-by-minute activity
Past 6 hours
Solar X-ray emission over time from the GOES satellites.
Sound made from the data of the past 6 hours. A higher pitch means stronger X-ray radiation from the Sun, measured by the GOES satellite. This is not the actual sound of the Sun.
Source: NOAA Space Weather Prediction Center, GOES satellite.
SOLAR WIND
What travels to Earth
Speed describes how fast particles move; density describes how many there are. A southward solar-wind magnetic field can help transfer energy into Earth's magnetic field, but does not guarantee a storm. Words such as “faster than usual” are our own thresholds, not an official scale.
Solar wind speed, density and magnetic field.
NOAA · THREE DAYS
Impact outlook
Percentages are the chance of the specified impact level on that day. G is the expected level, not a percentage.
NOAA outlook for the next three days.
FOR YOUR SELECTED PLACE
Next solar eclipse
Prague · default place
Calculating the local eclipse requires JavaScript.
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- Coverage at maximum
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- From your selected place, the Moon covers this share of the Sun at maximum. A higher percentage means more is covered; below 100%, coverage is partial.
- Begins
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- Maximum
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- Ends
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Your browser calculates the times with the Astronomy Engine program.
Never look at the Sun without certified eclipse glasses or a proper solar filter.
UNDERSTAND THE SUN
How to read today's Sun
What happens on the Sun?
Magnetic fields can rearrange and produce a flare. An image alone does not predict an effect on Earth.
Three messengers
Flare light reaches Earth in about eight minutes. Fast particles may take tens of minutes; the solar wind and clouds of solar material take hours to days.
Flare strength
Flares are grouped into X-ray classes A, B, C, M and X, each ten times stronger than the one before. M is a strong flare. M1 begins NOAA radio blackout level R1.
Solar wind and Bz
A southward magnetic field in the solar wind (called Bz) can couple more energy into Earth's magnetic field. It does not guarantee a storm on its own.
Effects in Czechia
Radio effects occur on Earth's sunlit side. Aurora needs a strong magnetic storm, darkness and clear skies.
Why we do not say how rare it is
NOAA R, S and G describe different effects. How often they occur changes with the Sun's eleven-year activity cycle, so a long-term average is not a forecast for today.
A FEW SURPRISES
What the numbers mean
THE SURPRISING PART
One event, three arrival times
A flare's light can reach Earth before the particles and the cloud of hot gas (plasma) released by the same event. That is why a strong flare is not the same as a magnetic storm here.
Light · ~8 minParticles · tens of minWind and clouds of matter (CME) · hours to days
How do we know?
Measurements and impact scales come from NOAA SWPC. Image pixels come from NASA/SDO. We label the capture time separately from the time a file was updated. Words such as “faster than usual” for the solar wind are our own thresholds, not an official scale; NOAA publishes the R, S and G scales.
Circles mark active regions with positions verified for the displayed image. Their absence alone says nothing about solar activity.