Hong Kong Observatory
Time-lapse photos show the subtle effect of a penumbral lunar eclipse.
It's no Supermoon, but if you look closely at the right time from the right place, you can see Earth's shadow darken the lunar disk early Wednesday — and even if you're not at the right place, you just might be able to catch the subtle celestial show online.
The penumbral lunar eclipse hits its peak at 9:33 a.m. ET (14:33 GMT), which is too late for the U.S. East Coast: By then, the full moon has set and the sun is up. South America, West Africa and Antarctica are also out of the picture. But most of the rest of the world will see at least part of the eclipse, such as it is. The chart below from NASA's eclipse website shows you what can be seen where, and TimeandDate.com helps you figure out the schedule for your own locale.
Fred Espenak / NASA
The white section of this map indicates where this week's penumbral lunar eclipse will be visible in its entirety. Observers watching from the light gray sections will see only part of the eclipse. No part of the eclipse can be seen from the dark gray section of the map.`
If you're in the eclipse zone, don't expect a spectacle like the total solar eclipse that took place earlier this month — or even like this year's other lunar eclipse, which darkened a piece of the Supermoon in June.
On Wednesday, the moon will pass through the lightest part of the shadow cast by our planet — the penumbra, which lets some sunlight shine through. If you could watch the event from the moon's surface, you'd see Earth cause a partial solar eclipse. The result is that the moon's brightness dims somewhat, but it's not enough to be noticeable unless you know what's coming.
What's more, the moon is at the farthest point of its orbit during this eclipse — about 30,000 miles (50,000 kilometers) farther away than June's Supermoon. The result is that the moon is about 30 percent dimmer than the Supermoon was.
The outlook for watching the eclipse online is dim as well. Slooh Space Camera is prepared to stream a telescopic video view of the moon from Hawaii at 9:15 a.m. ET (14:15 GMT), but the weather at the telescope site is not looking good, Slooh President Patrick Paolucci told me this evening.
"At this point, the penumbral event is in serious jeopardy," Paolucci said in an email. "The event will continue to count down on Slooh, but we may have to pull it tonight. ... We only go live when our feeds are live."
Perhaps the coolest thing about this eclipse is that it demonstrates one of the rules of celestial mechanics: Every time there's a total solar eclipse, you can count on having a lunar eclipse of some sort either two weeks earlier or two weeks later. That's because totality occurs when the sun, moon and Earth are precisely aligned during the moon's new phase — and the moon will still be lined up for an eclipse when it's facing Earth's far side for the full phase. The Inconstant Moon website provides further explanation of the eclipse seasons.
Even if the eclipse webcast is a washout, there'll be more cosmic shows to come: Paolucci says Slooh is planning a real-time video feed featuring Jupiter and its Great Red Spot on Sunday, starting at 8:15 p.m. ET (01:15 GMT Dec. 3). That's the night when Jupiter will be at its closest distance to Earth until the summer of 2021. Slooh's telescopic view is due to come from an observatory on the Canary Islands, accompanied by commentary from Paolucci and astronomer Bob Berman.
After that, stay tuned for the Geminid meteor shower, which peaks on the night of Dec. 13-14. This year's Geminids should make for a super show, because the moon will be in its new phase, leaving the skies clear for the sparkle of up to 100 shooting stars per hour. Factor in a series of space station sightings, and you've got more than enough to make up for a less-than-super lunar eclipse.
More about lunar eclipses:
- Flash interactive: What causes a lunar eclipse?
- Tips for photographing the penumbral eclipse
- Why the lunar eclipse won't cause madness
- Nine cool facts about lunar eclipses
- How super was that Supermoon?
Got eclipse? If you capture a super picture of the less-than-super moon, share it with the rest of us via NBC News' FirstPerson website for user-generated content. We'll publish a selection of images in a follow-up posting on Wednesday.
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.