Space Weather
Space weather is the ever-changing state of the space between the Sun and Earth — the solar wind, the interplanetary magnetic field, flares and coronal mass ejections. When it turns stormy it can light up the aurora, disturb radio and GPS, and stress power grids. This is your hub for tracking all of it live.
Open the live tracker →What space weather actually is
The Sun never stops. It streams a constant flow of charged particles — the solar wind — outward past every planet, carrying a tangled magnetic field with it. Most of the time Earth's own magnetic field deflects that flow harmlessly around us. But the Sun also erupts: flares blast radiation across the solar system in minutes, and coronal mass ejections (CMEs) hurl billions of tonnes of plasma toward Earth. Space weather is the study and forecasting of all these conditions and the effects they have on our technology and our skies. It is measured by spacecraft, ground magnetometers and X-ray sensors, and summarised for the public on three NOAA scales.
Solar wind
The particle stream from the Sun, typically 300–800 km/s. Faster, denser wind couples more energy into Earth's field. Solar wind →
IMF & Bz
The Sun's magnetic field carried by the wind. A southward (negative) Bz is the key that unlocks the aurora. Bz & solar wind →
Geomagnetic storms
When the field is disturbed for hours, the planet enters a G1–G5 storm and the auroral oval widens. Geomagnetic storms →
The aurora
The visible payoff — particles funnelling into the upper atmosphere and glowing green and red. See it live →
From the Sun to your sky
Space weather travels in a chain. A flare or an active region on the Sun launches a CME; the eruption ploughs through interplanetary space and, a day or three later, slams into Earth's magnetosphere. Sitting about 1.5 million kilometres upstream at the L1 point, spacecraft such as DSCOVR and ACE sample the wind first — giving forecasters roughly 15–60 minutes of warning before the shock arrives. The moment the interplanetary magnetic field tips southward, it links with Earth's field and lets solar energy pour into the polar regions. That energy accelerates particles down the field lines into the upper atmosphere, where they collide with oxygen and nitrogen and glow. Watching the L1 data is why a live aurora forecast can tell you something is coming before the sky ever brightens.
The three NOAA space-weather scales
Forecasters describe a storm's severity with three separate letter-and-number scales, because a single event can be dangerous in different ways. Each runs from 1 (minor) to 5 (extreme).
R — Radio blackouts
Driven by X-ray flares (C, M, X class). Strong flares ionise the dayside atmosphere and knock out high-frequency radio within minutes.
S — Radiation storms
Bursts of high-energy solar protons. They can threaten satellites, high-altitude aviation and, at extreme levels, astronauts.
G — Geomagnetic storms
Disturbances of Earth's magnetic field, roughly aligned with the KP index. G1–G5 is the scale that matters most for aurora hunters. KP index →
Why space weather matters on the ground
Space weather is not just a light show. Geomagnetically induced currents can overload transformers and trip power grids; the 1989 Québec blackout is the textbook case. Radiation storms force airlines to reroute polar flights and can degrade satellite electronics. Flares scramble GPS accuracy and HF radio used by aviation and shipping. For most people, though, the headline effect is the beautiful one: a strong geomagnetic storm drags the auroral oval down to latitudes that rarely see it, turning an ordinary night into a chance to catch the northern lights far from the poles.
Space weather FAQ
How is space weather measured before it reaches Earth?
The most important instruments sit at the L1 Lagrange point, about 1.5 million kilometres sunward of Earth, where the Sun's and Earth's gravity balance. Spacecraft there — currently DSCOVR and ACE — sample the solar wind's speed, density and magnetic field before it arrives, giving forecasters a short but crucial lead time. X-ray flares are watched separately and in real time by the GOES satellites in orbit around Earth.
What's the difference between a solar flare and a CME?
A flare is a sudden flash of electromagnetic radiation — X-rays and light — that reaches Earth at the speed of light in about eight minutes and mainly affects radio and the dayside atmosphere. A coronal mass ejection is a slower cloud of magnetised plasma launched from the Sun, taking one to three days to arrive. CMEs are the big drivers of geomagnetic storms and the strongest aurora. More on storms →
Does space weather affect me if I'm not chasing the aurora?
Usually not in a way you'd notice, but severe events can. Big geomagnetic storms have knocked out power grids, disrupted GPS precision, forced airlines to divert polar routes and damaged satellites. That's why national agencies forecast it. For day-to-day life the practical takeaway is simply that a strong storm is your best chance to see the aurora unusually far south. Get aurora alerts →
Track space weather live
Solar wind, Bz, the KP index and a single 0–9 Aurora Power score — updated every minute from satellite data at the L1 point.
Open the live tracker →