On Wednesday morning, the full moon will enter the shadow of Earth and darken ever so slightly in a penumbral eclipse. But potentially more interesting, especially for those on the East Coast, will be a very bright Jupiter, which will accompany the moon on Tuesday night.
For this eclipse, the central and western United States will be better positioned to catch the slightly — with an emphasis on slightly — darkened moon. Other parts of the world to see it include Australia, Asia and the Pacific, said noted eclipse expert Fred Espenak. Knowing about the eclipse on Wednesday morning may be more useful than seeing it — for practical purposes, the shading is so minuscule that it will be nearly indistinct from a regular full moon.
In lieu of the eclipse for those on the East Coast, steep some herbal tea and venture out on Tuesday night to behold the pleasantly plump waxing moon and its planetary companion Jupiter above it in the eastern sky.
Jupiter will be very bright at -2.5 magnitude, and the moon will be extremely bright at -12.4 magnitude. Jupiter reached opposition on March 8 — which means that the planet puts on a vibrant show all night long. Those lunar-planetary travel buddies cross the sky together, like a Bob Hope-Bing Crosby road picture, into the morning’s western heavens.
Officially speaking, the penumbral lunar eclipse reaches it greatest point on Wednesday at 7:48 a.m. Eastern Time (4:48 a.m. Pacific Time), which is about a half-hour after sunrise in Washington.
Earth produces two kinds of shadows: umbral and penumbral. As the moon slides through the dark part of Earth’s shadow (umbral), the moon turns a copper-like red and that event can be quite pronounced. When the moon moves through the outer shadow — the penumbral shadow — the eclipse features are less pronounced. In this case, it’s the outer, outer shadow.
Eclipses have families, and this one is called lunar eclipse Saros 142, which has been around since 1709. In cosmic terms, this specific eclipse family is quite young, so it is still in ascending node, which means that it will be a few hundred years before this family creates total lunar eclipses. There won’t be a total lunar eclipse in this family for another 200 years, as this is only the 18th out of 73, according to Espenak and NASA. For those keeping score, the last total lunar eclipse in this series will be April 21, 2665 — that’s 800 years after the American Civil War. The entire series ends in 3007.
The next total lunar eclipse of any family will occur on Jan. 31, 2018, in Saros 124.
In September, there will be another penumbral lunar eclipse, but North America — sadly — will be shut out from seeing it.