WASHINGTON — The harvest moon will dim slightly, possibly blushing red, tonight when a penumbral eclipse occurs.
Astronomers at the U.S. Naval Observatory report that the moon will edge into the fainter part of the Earth's shadow at 6:53 p.m., with the dimming most likely to be seen at the lower half of the moon's disc.
Although penumbral eclipses are often difficult to detect, this one should be both visible and interesting because of the brightness of the full harvest moon, astronomers say.
In addition, if there is significant dust in the Earth's atmosphere at the time--from forest fires or volcanoes--the result could be a red blush on the face of the moon. That's because, when light passes through dust, the blue part of the spectrum is scattered, letting a viewer see more of the redder hues.