A Lunar Eclipse Followed By A Comet

Skywatchers have something to look for the evening of February 10, 2017 and in the early morning for the next few days.

Feb 10 Lunar Eclipse

Friday, Feb 10th is the full moon, and a penumbral lunar eclipse. There are two types of lunar eclipses – umbral and penumbral.

Umbral lunar eclipses are the pretty ones we all think of, where the moon gets very dim as it moves to a point where Earth is directly blocking any sunlight from hitting it. Because of the light that refracts through Earth’s atmosphere, the moon takes on a red-orange color.

penumbral means that the moon is only in the wide shadow of the earth – the penumbra. The moon gets dimmer than normal, but it does not develop any of the red-orange color of an umbral eclipse.


So, it a penumbral eclipse that special? They account for about 3/4 of all lunar eclipses, and what you’ll see is a part of the full moon dim. The bottom line is you probably wouldn’t notice it if you weren’t looking for it. The moon gets dimmer, but it’s still extremely bright. When you think about what’s happening during even a penumbral eclipse though, it’s awesome! Because the edge of the umbra is so diffuse, it’s hard to track the shadow passing across the moon, even in a telescope. When you understand it’s the shadow of the Earth you are seeing, it’s a pretty impressive sight!

Eclipse Comparison

Where can you view the eclipse from? Just about anywhere except Australia, New Zealand, and Hawaii. Anywhere in North America, the moon will be in eclipse as it rises just after the sun sets. In Europe, the moon will be high in the sky, and the entire eclipse will be visible beginning to end. In Asia, the moon will be setting as it enters eclipse.

Eclipse timings and details can be found on the NASA eclipse website, which offers a convenient one page PDF with all the details.

Morning Comet

Next up is a morning comet. You’ll probably need at least binoculars and a relatively dark sky for this one. Comet 45P is speeding past Earth outbound from it’s close approach to the sun. It will pass nearest to Earth on Feb 11th, and will be moving away rapidly thereafter. You can download a finder chart for comet 45P (pdf) from the Skyhound website. The moon will unfortunately be shining brightly nearby to the comet most mornings, which will make it harder to spot. Look for a very diffuse star. While comets glow a pale green, the color is generally too faint to see visually, but shows up nicely in photographs.

Comet 45P

Speaking of photography, since this is a relatively bright and close comet, it should be possible to capture it in a relatively short exposure (say 10-20 seconds) with a 50-100 mm or similar lens. It won’t be hugely impressive, other than the fact that you can photograph a comet!

A different comet, LoveJoy. This is a cropped image using a Rokinon 85mm f/1.4 lens at f/2 and Canon T3i riding on a CG-5 mount. 15 x 15 sec exposures.
A different comet, LoveJoy. This is a cropped image using a Rokinon 85mm f/1.4 lens at f/2 and Canon T3i riding on a CG-5 mount. 15 x 15 sec exposures. Comet 45P should be somewhat larger and brighter.

Happy sky watching!


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