A solar flare and coronal mass ejection (CME) from the sun are expected to interact with Earth’s magnetic field, potentially producing visible northern lights (aurora borealis) in parts of the northern United States on Thursday, August 27, and Friday, August 28, according to the National Oceanic and Atmospheric Administration (NOAA).
The Space Weather Prediction Center (SWPC), a division of NOAA, has issued a G1 (minor) geomagnetic storm watch for August 27 and a G2 (moderate) watch for August 28, following the eruption of an M6.9 solar flare from sunspot 4513 on August 25. The flare was accompanied by a CME, a large cloud of magnetized plasma directed toward Earth.
Key developments:
- Thursday, August 27: A G1 geomagnetic storm is forecast, with a Kp index of 5, meaning the aurora could be visible in northern Michigan and other high-latitude regions of the U.S.
- Friday, August 28: A G2 geomagnetic storm is expected, with a potential Kp index of 5.67, which could extend visibility as far south as New York and Idaho (approximately 55 degrees geomagnetic latitude).
What to expect:
The partial lunar eclipse on August 27–28 will coincide with the aurora, providing an additional celestial event for observers. The eclipse will begin at 9:23 p.m. ET on August 27, reach maximum totality at 12:12 a.m. ET on August 28, and end at 3:01 a.m. ET.
Visibility of the northern lights depends on weather conditions and the strength of the geomagnetic storm. NOAA advises checking local National Weather Service forecasts for clear skies. Dark sky areas in northern states are recommended for optimal viewing.
How solar activity creates auroras:
The northern lights occur when charged particles from the sun collide with gases in Earth’s upper atmosphere, producing colorful displays. The intensity of the aurora is measured by the Kp index, which ranges from 0 (quiet) to 9 (extreme). A Kp of 5 indicates minor storm conditions, while a Kp of 5.67 falls within the moderate range.
NOAA’s three-day forecast accounts for both the CME arrival and a high-speed solar wind stream from a coronal hole, which may enhance geomagnetic activity. The exact timing of the CME’s impact remains uncertain, but early modeling suggests a glancing blow to Earth on August 28.
For those interested in observing the event, experts recommend using long-exposure photography or apps that track real-time aurora forecasts. The SWPC provides updates on geomagnetic conditions at spaceweather.gov.