WASHINGTON — February’s full moon is called the full snow moon because this is prime time for snow — at least in a normal winter, which we haven’t had here in the D.C. region this year. But the full snow moon will look a little different on Friday because it will undergo a penumbral lunar eclipse.
There are three types of lunar eclipses: total, partial and penumbral. All three occur when the full moon passes into the Earth’s shadow, which is caused by light from the sun. There are two components to our planet’s shadow — and all shadows actually — called the umbra and penumbra. The umbra is the central and darkest shadow zone, which projects about a million miles into space while the penumbra is the outer and lighter shadow zone.
Penumbral lunar eclipses are the least dramatic of the three types because, usually, there is only a slight shading. But for this penumbral eclipse, the full snow moon is deep within the penumbral shadow and misses the umbra by only 100 miles. The result will be shading that will be visible on the full snow moon similar to what you see in the picture I took of the penumbral phase of the Oct. 8, 2014, total lunar eclipse.
To see the eclipse is easy if the sky is clear. Just go outside and face the east and find the moon. You should be able to detect shading on the upper or northern face of the moon, starting at 6:14 p.m. Eastern Standard Time (EST). By mid-eclipse at 7:44 p.m., the shading will be at its greatest and should be easily visible. The penumbral shadow will start to move off the Moon and the last vestiges of it should be seen around 9:14 p.m.
The weather for Friday has clouds in the forecast, but it is still worth checking to see if the moon is visible. If clouds intervene you can watch the eclipse on the internet.
Comet approaching this weekend
You may have heard about the close approach of a comet this weekend. Comet 45P/Honda-Mrkos-Pajdušáková, or Comet 45P for short, will pass a mere 7.4 million miles from Earth on Saturday at about 3 a.m. EST.
Comet 45P is the closest comet we have had in more than 30 years, the last being the glorious Comet Hyakutake. That was a COMET! I still remember being at Shenandoah National Park photographing it on the night of closest approach. With just your eyes you could see the long tail stretch across almost the whole sky — and it moved against the background stars as you watched. While watching that bright comet move silently and majestically across the sky it was easy to understand why our ancestors feared them.
Comet 45P is beyond naked-eye visibility and even in binoculars or telescopes the brilliant full snow moon will make it difficult to see. You can tune in to a live show on the internet after the full snow moon eclipse.
By the way, you can see brilliant Venus in the southwest just after it gets dark with dim Mars just above it to the left. Jupiter makes its appearance in the southeast sky after 11 p.m., and Saturn rises in the hour before dawn in the southeast.
Follow Greg Redfern’s daily blog to keep up with the latest news in astronomy and space exploration. You can email him at firstname.lastname@example.org.