NOAA Forecasts Kp 4 Northern Lights Across 9 U.S. States Saturday Night

Q: Why can cameras capture brilliant aurora colors when the naked eye often sees only a faint white glow during mild celestial events?

Cameras show vivid aurora colors because they can collect and amplify faint light far better than the human eye can in darkness. During mild aurora events, the light is often too weak to strongly activate the eye’s cone cells, which detect color. In low light, human vision relies more on rod cells, which are good at sensing brightness and motion but poor at distinguishing color. That is why a weak aurora often looks like a pale white, gray, or faint green glow to an observer even when red, green, and purple wavelengths are present. A camera sensor works differently. With a long exposure, it can gather photons over several seconds instead of processing the scene instantly as the eye does. A wide aperture lets in more light, and higher ISO settings boost the sensor’s sensitivity. Together, those settings allow the camera to record subtle emissions from oxygen and nitrogen in the upper atmosphere that are too dim for the eye to separate into distinct colors. That is why NOAA’s forecast for only mild activity can still produce striking photos. Even when the display is not strong enough for vivid naked-eye color, a tripod-mounted camera or a smartphone in night mode can reveal the aurora’s greens, reds, and purples with much greater clarity. Stronger geomagnetic activity makes those colors easier for people to see directly, but cameras usually outperform human night vision in weaker shows.

3 articles · Updated · Forbes · Jun 27

A Kp index of 4 puts parts of nine northern U.S. states in line for mild auroral activity Saturday night, with the best viewing window generally between 10 p.m. and 2 a.m.
NOAA said no geomagnetic storm is expected, so visibility should stay limited to areas near the northern border rather than spreading farther south.
Northeastern Washington, northern Idaho, Montana, North Dakota, the far north of South Dakota, Minnesota, northern Wisconsin and Michigan's Upper Peninsula are in the forecast zone; Alaska has better odds, especially inland.
A Kp index of 1 is forecast for Sunday night, underscoring how quickly this weekend's activity is expected to fade.
June has still been relatively active, but scientists expect 2026 to be the last year of somewhat frequent U.S. aurora displays as the solar cycle moves past its peak.