Updated 21:41 UTC
The Sun today
Flares, sunspots and eruptions on the Sun are where every aurora begins. Here is what the Sun is doing right now, and what it may mean for the northern lights in the next few days.
The Sun right now
Fresh pictures from NASA's Solar Dynamics Observatory, a spacecraft that watches the Sun all the time.
Solar X-rays, last 24 hours
This is how bright the Sun is in X-rays, measured by the GOES satellite. Each step up the scale (A, B, C, M, X) is ten times brighter. A sudden spike is a solar flare.
Now: class B6.2 (quiet) · 21:40 UTC
Latest solar flare
Class C1.1 · small flare level
Peak at 17 Oct, 20:17 UTC
Below R1: too small to disturb radio. Flares from class M1 upwards can.
A flare by itself does not cause aurora: its light only affects radio on the day side of Earth. But big flares often launch a CME, and if that cloud hits Earth 1 to 4 days later, it can bring a strong aurora.
CMEs and storm watches
A coronal mass ejection (CME) is a huge cloud of solar gas thrown into space. If it is aimed at Earth, it can bring a geomagnetic storm and bright auroras 1 to 4 days later.
- Geomagnetic storm watch (G1) issued 17 Oct, 20:14 UTC. Expected: 18 Oct below G1, 19 Oct below G1, 20 Oct G1.
Biggest flares in the last 7 days
45 flares were recorded in the last 7 days: 45 C-class, 0 M-class and 0 X-class.
| Class | Peak (UTC) | Start (UTC) | End (UTC) | Radio blackout |
|---|---|---|---|---|
| C6.9 | 14 Oct, 02:21 | 14 Oct, 01:59 | 14 Oct, 02:39 | none |
| C6.0 | 16 Oct, 19:14 | 16 Oct, 19:11 | 16 Oct, 19:16 | none |
| C4.9 | 15 Oct, 15:55 | 15 Oct, 15:49 | 15 Oct, 15:59 | none |
| C4.2 | 13 Oct, 16:32 | 13 Oct, 16:08 | 13 Oct, 16:43 | none |
| C3.1 | 16 Oct, 00:19 | 16 Oct, 00:04 | 16 Oct, 00:27 | none |
| C3.0 | 16 Oct, 01:17 | 16 Oct, 01:04 | 16 Oct, 01:31 | none |
| C2.8 | 15 Oct, 17:55 | 15 Oct, 17:32 | 15 Oct, 18:03 | none |
| C2.8 | 15 Oct, 02:07 | 15 Oct, 02:00 | 15 Oct, 02:21 | none |
| C2.8 | 17 Oct, 04:10 | 17 Oct, 03:58 | 17 Oct, 04:15 | none |
| C2.2 | 14 Oct, 15:57 | 14 Oct, 15:48 | 14 Oct, 16:04 | none |
| C2.1 | 16 Oct, 19:06 | 16 Oct, 18:59 | 16 Oct, 19:11 | none |
| C1.9 | 14 Oct, 14:44 | 14 Oct, 14:40 | 14 Oct, 14:47 | none |
| C1.9 | 15 Oct, 23:59 | 15 Oct, 23:53 | 16 Oct, 00:04 | none |
| C1.8 | 11 Oct, 02:53 | 11 Oct, 02:46 | 11 Oct, 02:56 | none |
| C1.7 | 17 Oct, 15:40 | 17 Oct, 15:36 | 17 Oct, 15:44 | none |
Sunspot regions today
Numbered active regions observed on 17 October 2026. Bigger and more complex regions (magnetic class with G or D) are more likely to make large flares.
| Region | Position | Spots | Area | Magnetic class | Flare chance today |
|---|---|---|---|---|---|
| AR 4551 | S15W32 | 27 | 510 | Eki · BG | C 70% · M 15% · X 5% |
| AR 4557 | N17E01 | 29 | 110 | Dai · B | C 50% · M 10% · X 1% |
| AR 4555 | S07W84 | 1 | 10 | Axx · A | C 5% · M 1% · X 1% |
| AR 4554 | N07W10 | – | – | – | – |
| AR 4553 | N06W24 | – | – | – | – |
| AR 4556 | N03E03 | – | – | – | – |
| AR 4558 | S08W76 | – | – | – | – |
Area is in millionths of the visible half of the Sun. Position: N/S = north/south of the equator, E/W = east/west of the centre of the disc as we see it.
How the Sun drives the aurora
The Sun always blows a thin stream of charged gas into space, the solar wind. When it reaches Earth, a small part of its energy leaks into Earth's magnetic field and makes the gas high above the polar regions glow: that is the aurora.
Sunspots and the active regions around them hold strong, twisted magnetic fields. When they snap into a new shape, the Sun releases a flash of light (a flare) and sometimes throws out a CME. Dark coronal holes let fast solar wind escape, which often gives auroras again about every 27 days as the Sun turns.
Light from a flare reaches us in 8 minutes but does not cause aurora. A CME takes 1 to 4 days to arrive. When it hits and its magnetic field points south (negative Bz), the Kp index rises and the aurora can be seen much further from the poles.
What it means for tonight
Aurora forecast: Kp and solar wind Aurora alerts
Data: NOAA Space Weather Prediction Center (GOES X-rays, flares, active regions, alerts; public domain). Images: NASA/SDO and the AIA and HMI science teams (public domain). Times are in UTC.