Reference guide
GreenHalos field library
Aurora science,
without false precision.
Fourteen original English guides connect primary evidence to practical observing decisions. Each article remains fail-closed for search indexing until a real named author and human science reviewer are recorded.
0 of 14 guides have completed the editorial release gate.
Reference guide
Solar Flares vs Coronal Mass Ejections
A flare is chiefly a burst of electromagnetic radiation; a CME is an expulsion of plasma and magnetic field. They are related solar events, but they are not interchangeable. 3 primary-source recordsReference guide
What Is the Kp Index?
Kp compresses planetary geomagnetic disturbance into a familiar 0–9 index. It is useful context, but it is not a local sky forecast. 3 primary-source recordsReference guide
How to Read an Aurora Forecast
The most important question is not just ‘how strong?’ but ‘which horizon, which source, and which local conditions?’ 3 primary-source recordsReference guide
When Is the Best Time to See the Northern Lights?
There is no universal best clock time. The useful window is where darkness, clear sky and auroral activity overlap at your location. 3 primary-source recordsReference guide
How Sky Conditions Affect Aurora Viewing
Space weather controls whether aurora is active; the local atmosphere and Sun control whether its light can reach your eyes against a dark enough sky. 3 primary-source recordsReference guide
Why Does the Aurora Have Different Colours?
Auroral colour records which atmospheric species were excited, at what altitude and under what particle conditions—filtered through both the eye and the camera. 2 primary-source recordsReference guide
How Far South Can Aurora Be Seen?
There is no permanent southern boundary. The oval expands and shifts with geomagnetic activity, while visibility depends on direction, darkness, cloud and local horizon. 3 primary-source recordsReference guide
Northern Lights and Southern Lights Compared
Northern and southern aurora are two hemispheric expressions of the same Sun–Earth system, not different kinds of light. 3 primary-source recordsReference guide
How the NOAA OVATION Aurora Forecast Works
OVATION is a short-lead model of global auroral activity. It is most useful when its forecast time, source age and modelling limits stay visible. 2 primary-source recordsReference guide
What Do Solar Wind Speed and Bz Mean?
Speed describes how fast the solar wind is moving; Bz describes the north–south component of its magnetic field. Their effects depend on context and duration. 3 primary-source recordsReference guide
How to Photograph the Northern Lights
Start with a stable camera, a wide aperture and manual focus, then adapt shutter speed and ISO to how quickly the aurora is moving. 3 primary-source recordsReference guide
How Accurate Are Aurora Forecasts?
Forecast precision decreases with lead time: detailed short-range nowcasts, broader one-to-three-day activity forecasts and qualitative long-range outlooks should never look equally certain. 3 primary-source recordsReference guide