Some eclipses are spectacular, such as the annular solar eclipse of a couple of weeks ago. Others — well, not so much.

An example of the latter comes up tomorrow — a partial lunar eclipse. The full Moon — the Hunter’s Moon — will pass through the outer portion of Earth’s shadow, the penumbra. That part of the shadow isn’t very dark, so most people won’t really notice a difference in the Moon’s appearance.

Midway through the eclipse, the Moon will barely dip into the dark inner shadow, the umbra. At most, that part of the shadow will cover just six percent of the Moon — like someone carved a notch at the bottom of the lunar disk.

There’s a relationship between this month’s eclipses: They’re members of the same eclipse season.

Eclipses occur when the Moon crosses Earth’s orbit at just the right time, bringing Moon, Earth, and Sun into alignment. The alignment happens twice, about two weeks apart — an eclipse season. One alignment creates a solar eclipse, while the other creates a lunar eclipse. They can happen in either order. And if one eclipse is especially good — like this month’s annular eclipse — the other is usually poor — like tomorrow’s.

At least part of the eclipse will be visible across most of the globe. From the United States, though, only the northeastern states and northern Alaska will see any of it, and only for a few minutes — the final play of an eclipse season.

Script by Damond Benningfield

Support McDonald Observatory