Just when you thought the sun might be taking a breather, it's unleashed another powerful eruption — and the northern lights forecast just got even more promising.
A fourth coronal mass ejection (CME) erupted from the sun on Oct. 8, during a powerful M-class solar flare from the restless sunspot region AR4549. That brings the number of CMEs potentially heading Earth's way to four, raising the possibility of further geomagnetic activity and aurora displays over the coming days.
Early analysis suggests the latest CME could potentially catch up with the third CME on its way towards Earth.
Will the northern lights be visible in the U.S.?
NOAA's aurora forecast suggests auroral activity could be enhanced across northern North America. Exactly how far south the aurora might appear remains uncertain and depends on how the incoming CMEs interact with Earth's magnetic field.
G2 geomagnetic storm conditions are forecast for Oct. 9 and during such storms, auroras have previously been observed as far south as New York and Idaho.
While northern U.S. states currently have the best prospects, skywatchers farther south shouldn't completely write off their chances just yet. With multiple CMEs approaching Earth in quick succession, there's still considerable uncertainty over how geomagnetic conditions will develop. If the incoming eruptions interact favorably with Earth's magnetic field, auroras could potentially reach much farther south than currently anticipated.
So if you're at mid-latitudes, make sure those aurora alerts are switched on and your camera batteries are charged. This could be an interesting few days for northern lights enthusiasts!
For real-time forecasts based on your location, consider using a space weather app. A great option is "My Aurora Forecast & Alerts" (available for iOS and Android). For a deeper dive into space weather conditions, "Space Weather Live" is another excellent choice (available for iOS and Android)
Aurora forecast for the Northern Hemisphere courtesy of the U.K. Met Office
When should you look for the northern lights?
NOAA's latest 3-day forecast now places the strongest geomagnetic activity later on Oct. 9 than previously anticipated.
Minor (G1) geomagnetic storm conditions are forecast between 8 a.m. and 2 p.m. EDT (1200and 1800 GMT), with moderate (G2) conditions predicted between 2 and 8 p.m. EDT (1800 and midnight GMT).
Further activity is possible over the weekend, with NOAA currently forecasting minor (G1) conditions between 11 p.m. and 2 a.m. EDT on Oct. 10-11 (0300-0600 GMT Oct. 11).
For those wishing to catch some auroras, the advice remains the same! Keep your aurora alerts switched on and check conditions whenever skies are dark and clear. These forecast windows are not set in stone, particularly when multiple CMEs are involved!
When could the CMEs arrive?
This is where things get complicated.
Current modelling suggests the first CMEs could reach Earth on Oct. 9.
Space weather physicist Tamitha Skov notes that the two Oct. 6 CMEs could reach Earth in relatively quick succession, delivering a one-two punch to Earth's magnetic field. However, their journey may be influenced by the surrounding solar wind, making precise arrival times difficult to pin down.
The third CME could follow late Oct. 10 or early Oct. 11 (UTC), potentially prolonging unsettled geomagnetic activity and aurora prospects into the weekend.
And now there's a fourth CME to consider. Early analysis suggests this latest eruption is traveling faster than some of its predecessors, raising the possibility that it could catch up with the third CME before reaching Earth. The 'cannibal CME' could further complicate the timings and strength of resulting geomagnetic activity.
And remember, even an Earth-directed CME doesn't guarantee a spectacular aurora display. Much will depend on how the magnetic fields carried by these eruptions interact with Earth's magnetic field when they arrive.
With AR4549 still magnetically complex and facing Earth, more solar activity could be on the way. The sun sure is keeping us on our toes this week!
Editor's note: This article has been updated to include a fourth coronal mass ejection (CME) that erupted from the sun on Oct. 8, along with the latest geomagnetic storm forecasts and revised arrival estimates.