A geomagnetic storm lights up the night sky above the Bonneville Salt Flats on May 10, 2024 in … [+]
A few nights either side of Thursday, June 6 is potentially the best time for another display of the northern lights at low latitudes—such as Europe and North America—which ties in nicely with June’s new moon.
Solar activity has died down since May 10’s extreme G5 geomagnetic storm, which caused displays of aurora across the world. That’s largely because the area of the sun responsible for the intense space weather has moved.
Return Of AR3664
Solar flares and aurora-causing coronal mass ejections (eruptions of charged particles) come from sunspots—dark patches on the sun’s surface that are the scene of intense magnetic activity—but it’s generally only when they are close to the center of the sun that material flung into space is Earth-directed.
Since the sun rotates every 27 days, the sunspot that caused the May 10 event—AR3664—has been on the opposite side of the sun for a few weeks. However, it returned in late May to the southeast limb of the sun, announcing itself with a powerful X-class solar flare on Monday, May 27. A NASA model indicated that the resulting CME would miss Earth.
27 Days Later
Nothing is certain—it never is in space weather forecasting—but if AR3664 remains active, we could see aurora roughly 27 days after the May 10 event. Exactly 27 days later is June 6, the date of June’s new moon.
That’s crucial because only in dark skies is the aurora—particularly faint aurora—easily visible. An under-reported reason for the apparent brightness of May 10’s aurora was the night sky’s darkness (May’s new moon had been on May 8).
How To Prepare For Aurora
The best advice is to have a camera bag packed and a dark place nearby in mind to go to but don’t be rash. Wait for advice from experts. “Don’t make those decisions until we have eyes on the sunspot because it won’t be until the sunspot reappears and we can measure what it’s doing that we’ll be able to make a call on whether it’s similarly as complex or more complex than last time,” said Dr. Ryan French, a solar physicist at the National Solar Observatory (NSO) in Boulder, Colorado and the author of The Sun: Beginner’s Guide To Our Local Star. “That would be about seven or eight days before a CME.”
Reasons To Be Cautious
Since May 10, AR3664 has produced fewer solar flares, but the ones it has produced have been the strongest. So early indications are reasonable, but when it comes to solar physics, the past is not a reliable indicator of the future. It’s possible that AR3664 won’t be anywhere near as active by the time it’s Earth-facing. That’s what happened last time there was a sunspot this active, in September 2017.
“AR2673 was pretty similar—it got very complicated, had an X11 and X13 solar flare on September 6 and 10, then disappeared behind the sun,” said French. “Everyone was hopeful, but by the time it came back round, nothing happened. Sunspots can remain complex for a couple of rotations, but they can also decay.”
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Dr. Thomas Hughes is a UK-based scientist and science communicator who makes complex topics accessible to readers. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
