Total Lunar Eclipse – Saturday, April 4th

Sat, April 04, 2015

From Alex Filippenko:

There will be a lunar eclipse visible from much of North America before sunrise on the morning of Saturday, April 4 (this is, tonight — Friday night). The Moon will start entering Earth's dark shadow ("umbra") at 3:15 am PDT and it will exit at 6:44 am PDT, just before sunrise (around 6:50 am PDT); totality will be at 4:48-5:03 am PDT, lasting only 5 minutes (the shortest total lunar eclipse of the century). Western states are definitely favored; the Sun will alreayd be up (and the Moon will be down) at the time of totality as seen from the east of the Mississippi River, though at least a partial eclipse will be visible. An excellent website at which you can find out details for your specific viewing location is http://www.timeanddate.com/eclipse/in/usa/berkeley. Though the aboe URL is for Berkeley, CA, you can enter your own city near the top of the page and click "Search".

Passing near the edge of Earth's shadow, the totally eclipsed Moon will have a bright part and a darker part. The dark part will look some shade of yellow/orange/red, because that’s the color of sunlight that makes it through Earth’s atmosphere; violet/blue/green is being filtered out by air molecules and dust particles (think of a sunrise or sunset). Going through Earth’s atmosphere, the light bends toward the Moon and then reflects off its dark side back toward Earth. A totally eclipsed Moon is sometimes called a “blood moon” because of its reddish color, though I expect this particular one to look relatively bright orange/yellow (with perhaps some red in the darkest part) because the Moon will pass near the edge of Earth’s shadow. 

I encourage you to set your alarm for early Saturday morning, go to a suitable location, and take a look, at least for a short time near totality (4:58-5:03 am PDT); then you can go back to sleep, if you wish! To see it well, you won't need a very dark location or any equipment — your unaided eyes will suffice, and there is no danger whatsoever (unlike the case for a partial solar eclipse, where eye protection is needed). To make the Moon look larger, you might bring binoculars, but they aren't necessary to enjoy the view.  You should find a spot with a clear western horizon, if you want to watch the eclipse all the way to sunrise. 

By the way, this is the third of four consecutive total lunar eclipses spaced about 6 months apart — a relatively rare “tetrad.” The final one will be on Sunday night, September 27, 2015.

Clear skies and happy viewing, 

Alex