Space Weather — explanation & codes
Space weather covers all solar activity that affects the environment around Earth: energetic particles, magnetic fields and electromagnetic radiation. The data on Space Tracker comes from NASA's DONKI system (Space Weather Database Of Notifications, Knowledge, Information) and updates whenever a new event occurs.
⚡ Event types
CME
Coronal Mass Ejection
A CME is a massive cloud of charged particles (plasma) ejected from the Sun's corona at high speed — up to 3,000 km/s. If this cloud reaches Earth (1–3 days travel time) it can trigger a geomagnetic storm. Strong CMEs disrupt radio communication and satellite navigation (GPS), and in extreme cases can knock out power grids. CMEs are visible as crown-shaped eruptions in coronagraph images.
FLR
Solar Flare
A sudden intense brightening at the Sun's surface that emits X-ray and ultraviolet radiation. A solar flare travels at the speed of light and reaches Earth in about 8 minutes. The radiation ionizes the upper atmosphere (ionosphere) and disrupts shortwave radio, especially on the daylight side of Earth. Flare strength is classified from A (weakest) through B, C, M to X (strongest); each class is 10× stronger than the previous one. Class X10+ are extreme flares.
GST
Geomagnetic Storm
A geomagnetic storm occurs when a CME or a fast solar wind stream hits and disturbs Earth's magnetosphere. Its strength is measured with the Kp index (0–9) or the G-scale (G1–G5). A G1 storm has little effect; a G5 can damage power grids and satellites and produces auroras visible down to low latitudes. The Netherlands typically sees auroras at G3 and above.
IPS
Interplanetary Shock
A shock wave in interplanetary space that forms when a fast CME overtakes a slower solar wind stream, creating a compressed shock front. DONKI records when this shock passes instruments near Earth (e.g. the DSCOVR satellite at 1 million km). An IPS is usually a precursor to a geomagnetic storm that follows a few hours later.
SEP
Solar Energetic Particles
High-energy protons and electrons accelerated by strong solar flares or CME shock fronts. They reach Earth within minutes to hours and are dangerous for astronauts outside the magnetosphere (e.g. on the Moon or in deep space). On polar flight routes, pilots and passengers can receive an increased radiation dose. Strength is measured on the S-scale (S1–S5).
MPC
Magnetopause Crossing
The magnetopause is the boundary between Earth's magnetosphere and interplanetary space. Under normal conditions this boundary sits 10–12 Earth radii away on the daylight side. A strong CME can compress the magnetopause to 6 Earth radii or less — closer than geostationary satellites (6.6 Earth radii). An MPC notification means the magnetopause has reached the position of an observing spacecraft.
RBE
Radiation Belt Enhancement
The Van Allen radiation belts are two donut-shaped zones full of high-energy particles surrounding Earth. An RBE occurs when the outer belt is temporarily strongly enhanced by solar activity. This increases radiation exposure for satellites orbiting through the outer belt (MEO and some GEO orbits) and can damage electronic components.
📊 Severity scales
NOAA (the US weather agency) uses three five-point scales for space weather, similar to the Beaufort scale for wind.
G1 – G5
Geomagnetic storm
G1 = minor; G5 = extreme. Based on the Kp index. The Netherlands sees auroras at G3+.
S1 – S5
Solar radiation storm
S1 = minor; S5 = extreme. Measures high-energy protons. Dangerous for astronauts outside the magnetosphere.
R1 – R5
Radio blackouts
R1 = minor; R5 = extreme. Based on the X-ray flux of solar flares. Affects shortwave radio on the daylight side.
Kp 0–9
Planetary index
Updated every 3 hours based on measuring stations worldwide. Kp ≥ 5 = geomagnetic storm. Kp ≥ 7 = auroras in the Netherlands.
⚠ What does it mean for you?
| G-scale | Effect on Earth | Aurora |
|---|---|---|
| G5 (Kp 9) | Power outages possible, satellites disrupted, radio propagation lost | Visible as far as Florida and Spain |
| G4 (Kp 8) | Power grids under strain, GPS errors, HF radio heavily disrupted | Visible as far as northern Germany / Denmark |
| G3 (Kp 7) | GPS navigation issues, power fluctuations, increased satellite drag | Visible in the northern Netherlands under dark skies |
| G2 (Kp 6) | Minor power fluctuations, HF radio disrupted at higher latitudes | Possibly visible in Friesland / Groningen |
| G1 (Kp 5) | Minor disruptions to power grids, limited effect on satellites | Visible in Scandinavia and northern Canada |
🗺 Solar flare classes
Solar flares are classified based on the X-ray flux measured by the GOES satellites:
X
Extreme flare
Strongest class. X1 = minimum value, X10+ = exceptional. The most powerful ever recorded was X28 in November 2003. An X-class flare can launch a CME at the same time and causes widespread radio disruptions.
M
Medium flare
10× weaker than X-class. M-class flares cause brief radio disruptions on the daylight side. M5 and above are often accompanied by CMEs.
C
Minor flare
Barely noticeable on Earth. C-class flares are the most frequent and are considered background solar activity, especially during solar maximum.
B / A
Minimal activity
Flares below C-class. B-class flares are 10× weaker than C, A-class flares 10× weaker than B. No measurable effects on Earth. Also known as "microflares".
🔌 Data source
The space weather data on Space Tracker comes from the NASA DONKI API (api.nasa.gov). DONKI is updated daily by space weather forecasters at NASA's Goddard Space Flight Center. The data shows notifications from the past 7 days.
For current alerts and more detail: spaceweather.com or the NOAA Space Weather Prediction Center (spaceweather.noaa.gov).