0 In Astronomy

Eclipse, Penumbral Eclipse

This Friday night/Saturday morning, there will be a penumbral lunar eclipse! Now if you are not studying astronomy and thinking what the hell does penumbral mean… no worries. It is just a slightly lamer eclipse. I know I am really selling this! Ha! I kid though… eclipses are some of the greatest phenomena in Astronomy so despite its  not being as spectacular as its other counterparts, it will be pretty grand to check out! Very deserving of the James Bond title nod I gave it. What is even better is that no special tech (or luck) is needed to check out a lunar eclipse!

2016 Harvest Moon penumbral eclipse at 18:54 UTC by Giuseppe Donatiello

Now enough of my downplaying this phenomenon. It is time get to the science behind what is happening (and what you are observing). In a total lunar eclipse the Moon travels behind the Earth’s umbra which is part of the Earth’s shadow but not the whole thing. The umbra is the very dark central region (as you can see below). There is also the penumbra which is the lighter outer portions of the Earth’s shadow.  You can see this  phenomenon here on  Earth; shadows that aren’t too close to the body they are casting on appear blurry towards their edges. Actually if you want to humor me, lets check it out right now! In a lighted room take your hand over a white paper (or any flat light surface) slowly start to lift your hand and notice how the edges get blurred around your hand’s shadow. That lighter outside region is similar to the penumbra that the Moon is traveling through during this eclipse. Worth noting this picture is just to show the shadows; the Moon in this set up is heading into a total lunar eclipse.

Diagram of Umbra and Penumbra via NASA

How about when and where to view this thing! So the Moon enters the Penumbra at 6:42 pm EDT 2/10  (22:32 GMT 10/2) and is at its greatest at 8:43 pm EDT 2/10 (00:43 GMT  11/2). The Moon will finally leave the penumbra at about 10:55 pm EDT 2/10 (2:55 GMT 11/2).  Because this phenomenon isn’t as harsh as a total lunar eclipse, I would try to see it as close to when it is at its greatest as possible. Now about where… If it is nighttime out for you during those times then the Moon will be up and you can see this phenomenon.  So the western portion of the globe will view it at Moon rise (evening) , Africa/Europe and the central portions will see it when the Moon is highest in the sky (late at night), and the eastern portions of the globe will see it at Moon set (just before morning).

To see a map of where your city lies and what this particular eclipse will pass through during its journey check out NASA’s diagram here. Also if the weather isn’t permitting you can catch Slooh’s coverage which starts at 5:30 pm EDT 2/10 (21:30 GMT 10/2) here.

Happy Observing!



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