An eclipsed Moon rises over Alaska Wednesday, with aurora possible after

Alaska gets a narrow window Wednesday night, Aug. 26, for two things at once: a deep partial lunar eclipse and a possible aurora, on the first dark nights of the season.

The Moon rises over Anchorage around 8:10 pm already inside Earth's shadow, with 96% of its disk in the darkest part, dim and coppery against bright twilight. After sunset around 9:23 pm the shadow slides off. The partial eclipse ends at 9:52 pm, and the last faint penumbral shading clears by 11:01 pm. Best viewing runs roughly from 9:30 to 10 pm.

No equipment is needed. Unlike a solar eclipse, a lunar eclipse is safe to view directly. A clear view of the southeastern horizon helps, since the Moon will be low as it rises already in shadow. In Fairbanks, deeper into aurora territory, moonrise comes around the same time.

The aurora part

Separately, NOAA has issued a geomagnetic storm watch for Aug. 27 and 28. A coronal mass ejection from a solar flare earlier this week is arriving, and forecasters expect a Kp index of 3 to 4 on the 0-to-9 geomagnetic scale, with a chance of reaching Kp 5, minor storm level.

At Kp 3 to 4, aurora is possible across northern Alaska and a maybe for Anchorage. At Kp 5, it would be visible across much of the state. Fairbanks re-entered aurora season around Aug. 21, when nights finally got dark enough again after the summer's midnight sun.

The weather

The National Weather Service expects increasing clouds over Anchorage Wednesday night, with rain developing mainly after 1 am Thursday. That leaves the critical 9:30 to 11 pm window partly to mostly cloudy. Fairbanks looks similar, with showers likely after 4 am. In both cities, the weather worsens after the eclipse window closes.

What to know

The eclipse is certain geometry, visible whether the clouds cooperate or not. The aurora is only a forecast. A spectacular display usually needs Kp 5 or higher, possible but not likely.

Photographers may want a 200mm or longer lens on a tripod, pointed southeast at moonrise, to catch the eclipsed Moon low on the horizon with a foreground. If aurora appears to the north while the Moon sits to the south, that is the shot.

The Geophysical Institute at the University of Alaska Fairbanks runs a real-time aurora forecast at gi.alaska.edu/monitors/aurora-forecast.