The Northern Lights -- aka Aurora Borealis -- put on quite a display over Montana on Tuesday night and into early Wednesday.
A strong geomagnetic storm in Earth's atmosphere, coupled with mostly clear skies, made for a great opportunity for some Montanans to snap some amazing photos.
There is never a guarantee that the lights will be visible, and predicting specific times that they might be seen is not possible.
For many of these shutter-bugs, it was a combination of patience, preparedness, and being in the right place at the right time.
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Jim Thomas, who operates the Northern Lights "alert" site called Soft Serve News, says that a "watch period" began Tuesday evening, and was expected to continue for about 72 hours.
Soft Serve News notes: "Auroras are difficult to predict with precision. They have stops and starts (known as sub-storms). If you are out there, you need to be patient and lucky. Auroras happen in the upper atmosphere, so if there is cloud cover, you are out of luck."
Soft Serve News also offers a paid alert service (that includes a 14-day free trial) to notify subscribers of likely activity.
You can also visit the Space Weather Prediction Center website, which is operated by the National Oceanic & Atmospheric Administration.
It provides information about the aurora borealis, and also features aurora forecasts.
The SWPC center said on Tuesday that a G2 (Moderate) geomagnetic storm is in progress due to effects from a coronal hole high speed stream. G1 (Minor) to G2 (Moderate) geomagnetic storm levels will likely continue over the next couple of days with a chance to see isolated G3 (Strong).
Another tracking/alert site, Aurora Borealis Notifications, said on Tuesday: "Northern states bordering Canada, maybe just maybe the midwestern states, all of Canada, and all of Alaska have a super chance at seeing lights the next 3 nights." The site also offers tips on photographing the Northern lights.
If you plan to look for the Northern Lights, it's best to get outside of urban areas where there is less "light pollution." For people in and around Great Falls, many people have reported good luck if they drive just north of town, either up Highway 87 toward Fort Benton, or up Bootlegger Trail a few miles.