A wonderful event will take place this Sunday, September 27-28. That night skywatchers across the Americas, Europe and Africa will witness a total eclipse of the moon. And here’s the thing. Two things really. Well, OK, three things. First – it happens during convenient evening viewing hours. Second, it’s the Harvest Moon and third, it’s the closest Full Moon of the year.
Only rarely does a total lunar eclipse happen during a lunar perigee, the point in the moon’s orbit when it’s closest to Earth. When perigee occurs at or near full moon, we call it a supermoon. Supermoons are bigger and brighter than your average full moon because they’re closer to Earth. Sunday’s moon will be 8% larger than a typical full moon, but you’ll be hard-pressed to tell the difference because there’s no other moon hanging around to compare it to. Still, maybe some of you with an excellent visual recall will detect a size difference.
Lunar eclipses happen 2-3 times a year, but a supermoon eclipse is rare. The last one occurred in 1982 and the next won’t happen till 2033. Ready for the best part? Most U.S. observers won’t have to stay up late to watch this one. Partial eclipse, when the Earth’s shadow takes its first bite of moon pie, starts at 8:07 p.m. CDT (9:07 p.m. EDT, 7:07 p.m. MDT and 6:07 p.m. PDT). Total eclipse begins at 9:11 p.m. and ends at 10:23 p.m. That might be enough moon viewing for you. If not, stick around to 11:27 p.m. and you’ll see the moon pass through the partial phases in reverse and emerge in the clear again.
Total lunar eclipses last a long time – this one nearly 3 1/2 hours – and are perfectly safe to view throughout. The early times mean even children can stay up to watch. Have the little ones bring out crayons and paper and ask them to draw what they see. Wouldn’t that look nice hanging on your refrigerator?
Eclipses are very casual affairs. Watch as long or short as you like. The moon begins its saunter by first passing through the outer shadow or penumbra. Here, sunlight and shadow are mixed and the shading is too weak to see until about 20 minutes before the partial phases begin.
Sunlight passing around the circumference of the Earth gets scattered just like it does at sunrise and sunset; with the blues and greens removed, only the yellows, oranges and reds remain. In the same way a lens or prism bends sunlight, the remaining ruddy rays are bent by the atmosphere into the otherwise dark shadow cast by our planet. There they wait for the moon. When it arrives, they do a masterful job painting it the most amazing shades of warm color imaginable. The depth of color often depends upon the amount of particulate matter, called aerosols, present in the atmosphere. The more, say from a recent large-scale volcanic eruption, the darker the moon.
Just before, during and after totality are the best parts of a lunar eclipse, when the moon hangs like a fat red apple in a starry sky. Yes, stars. Before and early on in the eclipse, you’ll see few because they’re washed away by strong moonlight. But totality’s another thing. All that stellar goodness returns including the Milky Way, making for a strangely moving transformation.
The only factor we can’t control – and it’s true for all astronomical events – is the weather. Stay in touch with the local forecast or check the National Weather Service site. If you can’t escape the clouds by driving, there’s still hope. You can watch live webcasts of the event here and here. Finally, if you’d like to know how to take pictures of the eclipse, check out my photo tips article.
|Penumbra first visible||8:45 p.m.||7:45 p.m.||6:45 p.m.||5:45 p.m.|
|Partial eclipse begins||9:07 p.m.||8:07 p.m.||7:07 p.m.||6:07 p.m.|
|Total eclipse begins||10:11 p.m.||9:11 p.m.||8:11 p.m.||7:11 p.m.|
|Mid-eclipse||10:48 p.m.||9:48 p.m.||8:48 p.m.||7:48 p.m.|
|Total eclipse ends||11:23 p.m.||10:23 p.m.||9:23 p.m.||8:23 p.m.|
|Partial eclipse ends||12:27 a.m.||11:27 p.m.||10:27 p.m.||9:27 p.m.|
|Penumbra last visible||12:45 a.m.||11:45 p.m.||10:45 p.m.||9:45 p.m.|