The Northern Lights may be visible in the U.S. this weekend after a stream of solar wind escaped from a hole on the sun, followed by a coronal mass ejection. The potential display is slated for after dark on Sunday, Sept. 14, and into the early hours of Monday, Sept. 15.
While normally this event wouldn’t be expected to spark auroras, the equinox on Sept. 22 causes a seasonal geometry that can mean unpredictable and impressive displays.
It comes on the same weekend as a surprise meteor shower, a planet parade and news of both potential life on Mars and an incoming comet that could prove to be a naked eye object in October.
Northern Lights And The ‘Butterfly’ Coronal Hole
On Thursday, Sept. 11, NASA’s Solar Dynamics Observatory photographed a 310 miles (500,000 kilometers) wide coronal hole — a massive gap in the sun’s outer atmosphere — shaped like a butterfly. This area of open magnetic fields more easily releases charged particles into space.
A faint coronal mass ejection was also launched into space on Sept. 11. A CME is a cloud of charged particles that takes a few days to reach Earth — if it’s Earth-directed. According to Spaceweather.com, most of the material in this CME will pass south of Earth, but there’s a chance of a glancing blow on Sunday, Sept. 14.
If the CME does make contact, its arrival will likely coincide with the arrival of the solar wind stream, heightening the likelihood of geomagnetic activity — probably after dark on Sunday, Sept. 14 and into the early hours of Monday, Sept. 15.
Northern Lights: What To Expect This Weekend
The combined effects of the solar wind and CME could trigger G1 to G2-class geomagnetic storms. NOAA’s geomagnetic storm scale, runs from G1 (minor) to G5 (extreme). If a G1 storm results, auroras could be seen in northern skies along the U.S.-Canada border. If it reaches G2, auroras may be seen as far south as New York and Idaho. Skywatchers should keep an eye on NOAA’s three-day forecast, its latest aurora viewlines and its 30-minute forecast.
Northern Lights: Why To Be On Alert During Fall
Even a glancing blow of a CME can cause impressive — and unpredictable — displays of aurora during fall and spring, such as a G2-class geomagnetic storm on Tuesday, Sept. 9 that was not forecast. The cause is the Russell-McPherron effect, which sees the magnetic fields of the sun and Earth connect most efficiently for a few weeks either side of equinoxes. That tends to increase the intensity and frequency of geomagnetic storms. The fall equinox is on Thursday, Sept. 22, 2025.
October’s Comet, ‘Shooting Stars’ And Aurora
Scientists now think that Comet Lemmon (C/2025 A6) could be visible to the naked eye from dark skies during October. Its closest approach to Earth on Oct. 21 — when it should be at its brightest — coincides with both a new moon and the peak of the annual Orionid meteor shower overnight on Oct. 20-21, which produces about 20 “shooting stars” per hour. The continuing Russell-McPherron effect could also mean Comet Lemmon being seen against a backdrop of the Northern Lights.
Wishing you clear skies and wide eyes.
