Northern Lighthouse Colours

Northern Lighthouses communicate the conditions that cause auroras in the skies above Yellowknife using three colours: BLUE indicates overnight conditions will be calm, flashing GREEN indicates overnight conditions will be normal, and flashing RED indicates there is a possibility of geomagnetic storms overnight.


FLASHING BLUE: Solar activity has been very low for days and geomagnetic field conditions are very quiet. Despite the calm conditions, gentle auroras are still possible in the hours before and after local midnight.


FLASHING GREEN: The geomagnetic field will be quiet with unsettled periods overnight (which is normal). As a result, observers in Yellowknife should be on alert for auroras, with peak activity expected in the hours before and after local midnight.


FLASHING RED: A few days ago scientists observed an eruption on the Sun that launched an energetic gust of solar wind (plasma) towards Earth. The incoming Coronal Mass Ejection (CME) was expected to reach Earth today or tonight. As it sweeps past our planet’s magnetic field, the CME could trigger geomagnetic storms that spark vibrant auroras across the Northand across Canada. Be on alert for periodsof active (and colourful) auroras in the hours following a CME impact!