Northern Lights round 2 could shine Monday night thanks to a hole on the Sun
Aurora season is upon us, and it's off to a great start!
As we approach the Fall Equinox, magnetic connections between the Sun and Earth ramp up the Northern Lights, and we just witnessed a perfect example of this as brilliant auroras lit up the skies. Plus, we may see another round of auroras due to followup impacts of an immense coronal hole.
Social media was lit up in greens, reds, and purples overnight on Sunday, as amazing images and videos of the Aurora Borealis took over the feed, pouring in from locations across Canada and the northern United States.
The auroras over Témiscouata-sur-le-Lac, in SE Quebec, taken on the night of Sunday, September 14, 2025. (Virginie Gaulin/Instagram, used with permission)
The Northern Lights shine over Georgian Bay in this image captured from Parry Sound, ON, on Sep 14, 2025. (@BornThisWay1966/X.com, used with permission)
Three pictures captured from Leemington, ON, along the shores of Lake Erie, on Sep 14, 2025. (Michael Vincent Ledesma, used with permission)
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The source of these incredible displays was an intense but brief G3 geomagnetic storm. A geomagnetic storm is a disturbance to Earth's geomagnetic field caused by solar activity. They mainly result due to the constant flow of charged solar particles streaming away from the Sun (the solar wind), or from immense eruptions of solar plasma that often occur during solar flares (coronal mass ejections, aka solar storms).
This particular geomagnetic storm was brought on by Earth plunging into a blustery, energetic stream of the solar wind flowing out of an immense hole in the Sun's atmosphere.
An image from NASA's Solar Dynamics Observatory shows the large coronal hole in the Sun's atmosphere, while NOAA's ENLIL solar wind model shows Earth in the middle of the high speed stream of the solar wind emanating from that coronal hole (a CH HSS, or Coronal Hole High Speed Stream). (NASA SDO/NOAA SWPC)
Coronal holes are regions of the solar corona that become directly exposed to space due to the openings in the Sun's magnetic field. They appear dark against the rest of the corona because this exposure to space allows that region of the Sun to cool more rapidly. Thus, it emits less ultraviolet radiation compared to the rest, and shows up darker in images taken by satellites like NASA's Solar Dynamics Observatory (as shown above).
Although this coronal hole was aimed directly at Earth last week, the solar wind flowing out of it takes a slightly curved path in order to reach us here (also shown in the image above). Thus, the impacts of that energetic flow were delayed, and only showed themselves a few days after the coronal hole had rotated away from us.
Round two??
Geomagnetic activity ramped down throughout the day on Monday, from G3 (strong) to G1 (minor) during the morning hours, and then below storm levels by this afternoon.
However, according to NOAA SWPC forecasters, we may see another G1 (minor) geomagnetic storm on Tuesday.
No specific timing is given, at this time. However, those with clear skies throughout central regions of eastern Canada, as well as across the Prairie provinces, should be on the lookout for another potential round of auroras overnight.
Aurora season is heating up!
We are currently in a period of solar activity known as 'solar maximum' — when the Sun reaches the peak of its 11-year cycle of sunspots, solar flares, and coronal mass ejections (CMEs).
A comparison of the Sun's activity from the beginning of solar cycle 25 (in December 2019) and when solar maximum was announced (in October 2024). (NASA SDO)
According to NASA and NOAA, this period began nearly a year ago, and it expected to last at least until early 2026.
Each year, though, regardless of where we are in the solar cycle, the best time to see auroras (the so-called 'aurora season') is from mid-August to April.
Partly, this is due to the longer nights we experience here during northern Fall, Winter, and early Spring. However, it starts so 'early' and ends so 'late' because there are two strong peaks of activity each year that occur right around the spring and fall equinoxes.
The Northern Lights captured on March 23, 2023, by Tree and Dar Tanner in central Alberta (TeamTanner)
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The source of this uptick in aurora activity is a phenomenon known as 'equinox cracks'.
Basically, as Earth's molten metal core churns and circulates around, it produces a magnetic field that surrounds the planet. During most of the year, this geomagnetic field is misaligned with the Sun's magnetic field. As a result, the fields are more likely to repel each other. Since the solar wind and solar storms both carry a 'piece' of the solar magnetic field along with them as they move through space, this repulsion means that their impacts become diminished.
An artist's impression of Earth's geomagnetic field, normally invisible, emerging from inside the planet to act as a protective barrier against the strongest impacts of solar activity. (NASA)
However, twice each year, around the spring and fall equinoxes, the magnetic fields of Earth and the Sun align more closely. At those times, Earth's geomagnetic field is prone to forming direct connections with the magnetic fields carried by the solar wind and coronal mass ejections sweeping past us.
Those connections essentially form 'cracks' in the protective geomagnetic field. This opens up streamlined pathways for solar particles to stream, en masse, from space into the atmosphere. The result of this, typically, is an unusually intense and widespread display of the Northern Lights.
A wide shot of the September 14, 2025 auroras over Lake Erie, taken from Leemington, ON. (Michael Vincent Ledesma, used with permission)
Thus, with us so close to the fall equinox right now, any solar activity we encounter, whether it's a fast stream of the solar wind or a coronal mass ejection, could spark a bright display of the Aurora Borealis.
Keep your eyes on the sky!