# Is there a solar flare right now? > The Sun's X-ray level right now, live from NOAA's GOES satellites, as a flare class from A to X: what a flare is, what it does here, and the biggest on record. HTML: https://www.theuniversecounts.com/solar-system/space-weather/solar-flares Numbers as of 2026-10-31 03:44 UTC. Live ones keep changing on the HTML page. Right now the Sun's X-ray level is B2.0, measured every minute by NOAA's GOES satellites. Flares are graded A, B, C, M and X, each letter ten times stronger than the one before. Only M and X flares are strong enough to disturb radio on Earth. The last of those began 12 days ago. A flare's light reaches us in 8.3 minutes, so the moment we see one, its X-rays are already here. - The Sun's X-ray brightness at Earth (GOES, 0.1–0.8 nm): B2.0 - Time since the last major solar flare (class M or X): 12 days - Planetary K-index (Kp), latest 3-hour value: 3 - Sunspot number, monthly mean (latest month): 60.3 ## A flash on our star What is a solar flare? The Sun is a star, a huge ball of hot gas held together by its own gravity and lit by fusion in its core. Its gas is electrically charged, and its churning makes strong, tangled magnetic fields. Where they push up through the surface, we see dark sunspots. Above a group of sunspots, the twisted field can snap into a calmer shape. It lets go of its stored energy within minutes, as a burst of light across every colour, from radio waves to X-rays. That burst is a solar flare. NASA calls flares the most powerful explosions in the solar system. Here on the ground we are safe. Earth's air and its magnetic field, the shield we live inside, stop a flare's harmful radiation long before it reaches us. ## From A to X The flare scale Flares are measured by how brightly they shine in X-rays, as seen from Earth's orbit. NOAA's GOES satellites watch the Sun's X-rays without a break, and the strongest reading of a flare gives it a letter: A, B, C, M or X. Each letter is ten times the one before. So an X flare is ten times an M, and a hundred times a C. A number adds detail inside a class: an M2 is twice an M1. The X class has no top, because nothing caps how strong a flare can be. On a quiet day the Sun sits in the B or C class, with small flares coming and going. Right now it reads B2.0. Big flares come most often near the peak of the Sun's 11-year cycle, when it is crowded with sunspots. ## What a flare does here Radio blackouts A flare's X-rays and ultraviolet light travel at the speed of light. They hit the top of our atmosphere on the side of Earth facing the Sun at the moment we see the flare, with no warning at all. The extra light charges up the lower layers of the ionosphere, high above our heads. Shortwave radio normally bounces off the layers above, which lets pilots and sailors talk across oceans. During a strong flare those signals are swallowed instead. That is a radio blackout, and it lasts from minutes to hours. NOAA's blackout scale starts at the M class. The last flare of class M or X began on 19 October 2026. Flares often come with a second eruption, a cloud of charged gas called a coronal mass ejection. That cloud is far slower than light. If it is aimed at Earth, it can arrive a day or more later and set off a geomagnetic storm. ## The biggest flares on record 4 November 2003 · 3 October 2024 The strongest flare ever measured erupted on 4 November 2003, at the end of a burst of activity around Halloween. It was so bright that it overwhelmed the X-ray sensor on the GOES satellite for 12 minutes. Working from the parts it did record, NOAA estimated its peak at X28. The flare went off near the edge of the Sun, pointing away from us, so Earth escaped the worst. In the cycle we live in now, Solar Cycle 25, a great flare came on 3 October 2024. It peaked at X9.0. When it erupted, NOAA called it the most powerful flare so far in this cycle. GOES has measured the Sun's X-rays only since 1976. The great flare that Richard Carrington saw by eye in 1859 came long before, so nobody knows its class. It was followed by the largest geomagnetic storm on record. ## FAQ ### Is there a solar flare right now? The Sun's X-ray level is B2.0 right now. A reading in the M or X class means a strong flare is under way. The level comes from NOAA's GOES satellites and updates every minute. ### What is an X-class flare? The strongest kind. An X flare is ten times brighter in X-rays than an M flare and a hundred times brighter than a C. X1 is the bottom of the class, and there is no top: the record, on 4 November 2003, was estimated at X28. ### When was the last big solar flare? The last flare of class M or X began on 19 October 2026, 12 days ago. ### Can a solar flare hurt us on Earth? Not on the ground. Our atmosphere and magnetic field absorb the harmful radiation. Strong flares can black out shortwave radio on the daylit side of Earth, and they can affect satellites and astronauts. ### How long does a flare take to reach Earth? Its light arrives in 8.3 minutes, at the speed of light, so we see the flare and feel its X-rays at the same moment. A coronal mass ejection launched with it travels far more slowly and can take days. ## Related - [What is the Sun doing right now?](https://www.theuniversecounts.com/solar-system/the-sun/what-is-the-sun-doing-now.md) - [Geomagnetic storms](https://www.theuniversecounts.com/solar-system/space-weather/geomagnetic-storms.md) - [The Sun](https://www.theuniversecounts.com/solar-system/the-sun.md) - [The solar cycle](https://www.theuniversecounts.com/solar-system/the-sun/solar-cycle.md) Somewhere on the Sun's face, a knot of magnetism is winding tighter as you read. When it lets go, would you want to know? ## Sources - Diameter of a regulation football (size 5) (Measured, with error): [The IFAB: Laws of the Game, Law 2 – The Ball](https://www.theifab.com/laws/latest/the-ball/) - Earth's diameter at the equator (Measured): [NASA NSSDCA: Earth Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html) - Peak X-ray flux of the 3 October 2024 flare (X9.0) (Measured): [NOAA NESDIS: Sun Releases Strong X9.0 Solar Flare](https://www.nesdis.noaa.gov/news/sun-releases-strong-x90-solar-flare) - Peak X-ray flux of the 4 November 2003 flare, the strongest measured (estimated) (Estimated): [NOAA National Weather Service: Intense Space Weather Storms, October 19 – November 07, 2003 (Service Assessment)](https://www.weather.gov/media/publications/assessments/SWstorms_assessment.pdf); [NASA Science: Solar Storms and Flares](https://science.nasa.gov/sun/solar-storms-and-flares/) - Planetary K-index (Kp), latest 3-hour value (Measured, with error): [NOAA SWPC: Planetary K-index](https://www.swpc.noaa.gov/products/planetary-k-index); [NOAA SWPC: NOAA Space Weather Scales](https://www.swpc.noaa.gov/noaa-scales-explanation) - Speed of light in a vacuum (Measured): [BIPM: SI defining constants](https://www.bipm.org/en/measurement-units/si-defining-constants) - Sunspot number, monthly mean (latest month) (Measured, with error): [NOAA SWPC: Observed solar cycle indices](https://services.swpc.noaa.gov/json/solar-cycle/observed-solar-cycle-indices.json); [SILSO, Royal Observatory of Belgium: SILSO data files](https://www.sidc.be/SILSO/datafiles) - The International Space Station's orbital speed (Measured): [NASA: Station Facts](https://www.nasa.gov/international-space-station/space-station-facts-and-figures/) - The Moon's average distance from Earth (Measured): [NASA: Moon Facts](https://science.nasa.gov/moon/facts/) - The Sun's distance from Earth (Measured): [NASA NSSDCA: Sun Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html) - The Sun's X-ray brightness at Earth (GOES, 0.1–0.8 nm) (Measured): [NOAA SWPC: Solar Flares (Radio Blackouts)](https://www.swpc.noaa.gov/phenomena/solar-flares-radio-blackouts) - Time since the last major solar flare (class M or X) (Measured, with error): [NOAA SWPC: GOES X-ray Flux](https://www.swpc.noaa.gov/products/goes-x-ray-flux)