Northern Lights may still shine across Canada Wednesday night
The solar storm that erupted on Sunday apparently swept by us with little impact, but a second could spark auroras Wednesday night.
We may see the Aurora Borealis across Canada tonight, due to a solar storm sweeping past Earth.
Late in the day on Sunday, July 21, an immense plasma cloud erupted from the surface of the Sun. This 'halo CME', so-called because it appears to surround the Sun as it expands into space, is on a trajectory towards Earth.
Originally, this coronal mass ejection was forecast to arrive here in the early hours of Wednesday, July 24.
Watch below: Camera in space captures Sunday's 'halo' CME, plus two more (wait 'til the end)
According to real-time solar wind readings, NASA's Advanced Composition Explorer (ACE) did measure an uptick in solar particles passing by the satellite in the middle of the afternoon on Tuesday, July 23. This CME appeared to have little effect on Earth's geomagnetic field, though.
However, in the latest update from NOAA's Space Weather Prediction Center, forecasters are tracking a second cloud of solar particles following along behind the first. This second CME is expected to reach Earth on Wednesday.
Four panels of the ENLIL solar wind model show the progress of the two coronal mass ejections (CMEs) as they travel between the Sun and Earth, with the first arriving around midday on Tuesday, and the second expected to reach Earth early on Wednesday. (NOAA SWPC)
In anticipation of this, SWPC forecasters have pushed back their G2 geomagnetic storm watch until early Wednesday evening.
Depending on the impact of this solar storm, it could spark bright displays of the Northern Lights across Canada and some northern regions of the United States.
According to SWPC, a G1 (minor) geomagnetic storm is forecast to occur between 18 UTC to 21 UTC (2 p.m. to 5 p.m. EDT), with a G2 (moderate) storm following it, from 21 UTC to 00 UTC (5 p.m. to 8 p.m. EDT).
Aurora activity tend to be strongest for locations that are directly opposite to the Sun during the geomagnetic storm. Thus, based on the timing of this event, it appears to favour northern Europe. However, depending on conditions at the time, activity could persist long enough to be visible over parts of Canada, as well.
The above map plots the southernmost visibility of the auroras based on the geomagnetic storm strength (G1-G5) and their corresponding Planetary K-index (Kp) value (Kp 3 through 9). For Wednesday evening's G2 geomagnetic storm, auroras could become visible as far south as between the green and yellow lines.
DON'T MISS: Out looking for auroras? Here's what else you can see in the night sky this summer
Bright far-side eruptions
Although Sunday's CME was quite faint, it was followed up on Monday night and Tuesday morning by two far brighter events.
These two composite views of the CMEs on July 22 and July 23 combine coronagraph images from the Solar and Heliospheric Observatory taken at roughly the same time, along with extreme UV views of the Sun from the Solar Dynamics Observatory. (NASA/ESA, NASA SDO, Scott Sutherland)
Unfortunately, at least for aurora enthusiasts, both of these solar storms erupted from the far side of the Sun. Thus, they will not have any direct impact on Earth.
However, Tuesday morning's event did manage to bombard Earth with solar protons, sparking a solar radiation storm that lasted much of the day.
According to the Solar Influences Data Center (SIDC) at the Royal Observatory of Belgium, this was caused by a powerful solar flare. Based on data from the ESA's Solar Orbiter spacecraft, currently on the opposite side of the Sun from Earth, it was estimated at X14-class — possibly the strongest flare so far of this solar cycle.
That flare and the halo CME that followed it caused protons in the Sun's corona to be accelerated to nearly the speed of light and scattered out in all directions, including towards Earth. While Earth's atmosphere is an effective shield against the effects of solar radiation storms, satellites and spacecraft in orbit can be impacted by these events. Fortunately, it was only a minor solar radiation storm, with little overall effect.
Even though all of this took place on the other side of the Sun, all of this activity points to the potential for some interesting space weather starting sometime over the next week.
Active regions 3763 and 3764, on the eastern limb (left edge) of the Sun, show up bright in this combined view from the Solar Dynamics Observatory, with many overlapping coronal loops. In the background, beneath AR 3763/3764, is where Monday night's CME erupted, indicating the presence of another active region there. Active regions are areas on the Sun with tangled magnetic fields, which show up as dark sunspots and sunspot groups on the surface. An image of the Earth is provided (bottom left corner) for scale. (NASA SDO/Helioviewer.org)
The bright area shown along the left edge of the Sun in the image above is a combination of two different active sunspot groups. However, those appear to be just a prelude of what is coming. The active region responsible for Monday evening's CME is located to the south of AR 3763/3764 and still just beyond our view. It should be rotating into view a few days from now.
The active region that produced the X14-class flare and bright halo CME on Tuesday morning appeared to be on the exact opposite side of the Sun from us at that time.
With the Sun taking 27 days to complete a full rotation, it should only take one-quarter of that time — roughly a week — for that active region to appear along the Sun's eastern limb. So, around Monday or Tuesday of next week, July 29-30, we'll have a better indication of what it may have in store for us.
(Thumbnail image is courtesy Nancy Mackay, who captured this view of the Northern Lights from Minnedosa, Manitoba on December 24, 2023, and shared the image in The Weather Network's UGC gallery)
