A Night When the Aurora Borealis Appeared Over Boulder County (November 11, 2025)

On November 11, 2025, shortly after sunset, the Aurora Borealis was observed in Boulder County.

Table of Contents

Geomagnetic Storm Conditions
From My Front Yard
Preparing to Photograph the Aurora
Davidson Mesa (Louisville Area)
Aquarius Trailhead (Louisville)
Reflections on Shooting the Aurora
In Conclusion
Related Link
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Geomagnetic Storm Conditions

That night’s geomagnetic storm reached an extremely rare intensity—G4 on NOAA’s G-scale (with G5 being the maximum). The global Kp index reached approximately 8.7, nearly the highest possible level.

From My Front Yard

Near the end of the display, the aurora was visible even from my front yard as a faint, cloud-like glow. When photographed with an iPhone 13 mini, the lower portion appeared green, while the upper part showed reddish-purple hues.

Preparing to Photograph the Aurora

The first rule of aurora photography—as with all night-sky imaging—is to find a dark location. We brought cameras, a lightweight tripod, and an ultra-wide lens (Laowa 6 mm, equivalent to 12 mm full-frame) to a trailhead with minimal light pollution.

Davidson Mesa (Louisville Area)

We parked near Harper Lake and captured the aurora reflected above the water shortly after 8:00 p.m. local time on November 11.

Aurora Borealis（Louisville, Colorado）
Date and Time: November 11, 2025, after 8:00 p.m.
Camera: Lumix G100D + 8–18 mm (16–36 mm equivalent)

The colors in the sky—green at lower altitudes and red higher up—were caused by energy transitions in oxygen atoms at different heights. Some reddish-purple and blue tones were produced by nitrogen emissions at lower altitudes.

Aquarius Trailhead (Louisville)

We also photographed the aurora from the Aquarius Trailhead in Louisville using an iPhone 13 mini, although the images taken with our mirrorless camera did not turn out as well.

Reflections on Shooting the Aurora

Although we used both a mirrorless camera and an iPhone, the iPhone produced the most vivid images thanks to its internal image processing—especially in long-exposure night mode.

In Conclusion

Seeing the aurora from Colorado is an experience few people have in their lifetime. Many locals around us said it was the first time they had ever seen it. While places such as Whitehorse or Yellowknife in Canada—or Fairbanks in Alaska—are classic aurora destinations, this night underscored just how extraordinary such a sighting in Colorado truly was.