Seven Ways To Savor The Upcoming Total Eclipse Of The Moon

Next Monday night April 14-15, skywatchers across much of North and South America will get to see a total eclipse of the moon. Lunar eclipses last for hours and can be safely viewed with the naked eye. This photo was taken of the June 2011 eclipse. Credit: Muhammed Mahdi Karim

It’s been too long. The moon last slipped into Earth’s shadow for North America in Dec. 2011. Next Monday night’s eclipse will end the current dry spell and make for a thrilling night out.

Map showing where next Monday night’s (April 14-15) eclipse will be visible. The western hemisphere has prime viewing seats. Credit: Fred Espenak

This eclipse is the first of four total lunar eclipses spaced about six months apart that will be visible across most of the Americas. The others occur on Oct. 8 this year, April 4, 2015 and Sept. 27, 2015. This particular sequence of four total lunar eclipses with no partials in between is called a ‘tetrad’. While we all hope for clear skies, if the weather’s uncooperative next week, you won’t have to wait long for another eclipse.

Eclipse tetrads explained

Lunar eclipses unfold slowly, lasting up to five hours. Unlike a total solar eclipse, where the sun disappears at most a few minutes, totality during a lunar eclipse can easily last more than an hour, giving you lots of time to enjoy the spectacle.

The only downside will be the late hour. Try to get some shuteye early as most of the eclipse happens after midnight in the wee hours Tuesday morning.

Because the moon’s orbit is tilted 5 degrees, the full moon normally misses the cone of shadow cast by the Earth and we see no eclipse. But several times a year, the moon’s orbit intersects Earth’s at the time of full moon and we see an eclipse. The Credit: Wikipedia

Lunar eclipses occur during full moon when the sun, Earth and moon line up in a neat row, and the moon passes into the shadow cast by our planet. You’d think eclipses would happen every full moon, but they don’t because the moon’s orbit around the Earth is tipped 5 degrees to Earth’s orbit around the sun.

The moon’s tipped orbit (red) is the reason we only get occasional eclipses at full moon. Most of the time the moon is either a little above or below the ideal alignment. Credit: Bob King

The moon spends most of the time above or below the plane of Earth’s orbit. And since Earth casts a shadow across its orbital plane, a lunar eclipse can only happen if the moon happens to be crossing that plane at the same time it’s full. That’s why eclipses are such a now and again thing.

While total solar eclipses are only visible along a narrow strip of land or ocean, a total lunar can be seen across half the globe wherever the sky is dark and the moon is up.

The moon’s past from west to east (right to left) across the dual shadow cast by Earth. The diagram shows key times (CDT) during the eclipse listed in the table below. Credit: Fred Espenak with additions by the author

Earth’s shadow is composed of two nested components – the inner umbra, where the Earth completely blocks the sun from view, and an outer penumbra, where the planet only partially blocks the sun. Because the penumbra is a mix of shadow and sunlight, it’s nowhere near as dark as the umbra.

An eclipse is divided into stages beginning with the moon’s entry into Earth’s lighter penumbral shadow. Most of us won’t notice any shading at all until about a half hour in, when the moon is deep enough inside to reveal a subtle darkening along its eastern edge. The table below lists the times for each stage of the eclipse across the four time zones:

Eclipse Events                     EDT             CDT                 MDT                PDT

Penumbra visible 1:20 a.m. 12:20 a.m. 11:20 p.m. 10:20 p.m.
Partial eclipse begins 1:58 a.m. 12:58 a.m. 11:58 p.m. 10:58 p.m.
Total eclipse begins 3:07 a.m. 2:07 a.m. 1:07 a.m. 12:07 a.m.
Mid-eclipse 3:46 a.m. 2:46 a.m. 1:46 a.m. 12:46 a.m.
Total eclipse ends 4:25 a.m. 3:25 a.m. 2:25 a.m. 1:25 a.m.
Partial eclipse ends 5:33 a.m. 4:33 a.m. 3:33 a.m. 2:33 a.m.
Penumbra visible  ——– 5:10 a.m. 4:10 a.m. 3:10 a.m.
During a total lunar eclipse (seen on Earth) an astronaut on the moon would instead see the Earth cover the sun, its atmosphere aglow with the combined light of all the sunrises and sunrises “leaking” around the rim of the planet. The light would bathe the moonscape in deep orange light. Stellarium

Partial eclipse begins when the moon treads within the dark umbra. Nibble by nibble the shadow eats away at the lunar disk. When only a sliver of the moon remains in sunlight, you’ll notice the shadowed portion glowing an eerie red or deep copper. To understand why, imagine an astronaut on the moon looking back at Earth during the eclipse.

During the next Tuesday morning’s eclipse, the moon will be just 1.5 degrees from Spica and not far from the planet Mars in the southern sky. Don’t forget to give Saturn a nod, located about two “fists” to the left of the moon. Stellarium

From her perspective, as the Earth passes in front of the sun, it’s surrounded by a glowing red-orange ring of light. Our atmosphere bends the light from all the sunrises and sunsets around the planet’s circumference into the umbra, coloring the moon red. Earth’s shadow isn’t really black after all but more a deep rusty red. Back on Earth, the moon will hang like a ghostly amber globe near the bright star Spica.

After mid-eclipse, the moon slowly exits the Earth’s shadow and performs the whole show in reverse, transitioning back to partial eclipse and finally exiting the penumbra.

Different aspects of a total lunar eclipse from start to near finish photographed in Hefei, China on Dec. 10, 2011. Credit: Reuters

You can take in the eclipse as casually as you like, but are seven cool things you might like to watch for:

#1 – When will you detect the first hint of penumbral shading? Keep an eye on the eastern (left) side of the moon for a “dented” appearance.

#2 – What color and how bright is the totally eclipsed moon? Depending upon the aerosol content of the atmosphere (greatly affected by volcanic eruptions), eclipses range from bright copper to dark brown and even black. Try rating this one on the traditional Danjon scale where “4” is bright and “0” is nearly invisible.

#3 – Watch for “the night within the night” phenomenon. If you thought it was dark out at the start of the eclipse, you’ll be amazed at how inky the landscape becomes during totality. As the eclipse progresses, the stars and Milky Way return to view.

#4 – With the entire moon darkened during totality, it will be relatively easy to watch it block or occult any star within its path. Many stars ranging from magnitude +8 and 12 will be occulted when viewed through small to medium telescopes. Click HERE for stars and times.

#5 – Binocular and telescope users should also look for a blue tinge to the encroaching umbral shadow as it slowly envelops the moon caused by light refracted by the upper atmosphere’s ozone layer.

#6 – Variation in the moon’s brightness. The top half will be closer to the center of the umbra and appear darker than the bottom. How obvious will this be?

#7 – Bring home a souvenir with your camera. If you have a telescope, you can hold a cellphone over the eyepiece to get great shots of the bright phases. During total eclipse, longer exposures of 1 to 10 seconds are necessary. For that you’ll need a tripod and a camera that can shoot time exposures. Telephoto lenses will pump up the moon’s size, but even a standard lens can do a great job of recording the sunset-colored moon in a landscape setting. Set your lens to its widest-open setting (f/2.8, 3.5) and expose 10-30 seconds to include the scene.


12 Responses

  1. Edward M. Boll

    I just skimmed your article. I do not know if you mentioned it but Mars will be near by the eclipsed Moon.

    1. astrobob

      Hi Edward,
      Yes, I have a sky view with the eclipsed moon further down showing Spica, Mars and Saturn, too. Thanks!

  2. Troy

    That’s a great list of things to do during the eclipse. Because lunar eclipses are so long even the most patient observer will need some sort of distraction. If it is clear I’d like to photograph the entire eclipse frame by frame and string the images together as a video. By 5:30 a.m. on the 15th I’m looking at the moon about 12 degrees above the horizon. Barren trees will probably help. I have an alternate observing site for seeing things near the horizon, but no electricity there.
    If it is not clear I might attempt some through the cloud imaging. I’m surprised just how much detail a moon under the clouds can actually show, just adjust the exposure. (Of course the eclipsed moon is going to have a tougher time making it through the clouds)

    1. astrobob

      Hi Troy,
      I hope you get great weather and can get the photos you hope for. I’d like to get a couple nice, high-res. shots of totality and maybe a modest sequence and a scene or two. Like you said, there’s so much time to do anything you’d like during a lunar eclipse.

  3. Kelly

    Re: North America not having seen a total lunar eclipse since 2010 – although the total phase began after moonset where you live, for those in the western regions the last one was actually on December 10, 2011 (which was the last one anywhere in the world – all the lunar eclipses since were either partial or penumbral).

    1. astrobob

      Thanks for pointing that out Kelly. Yikes – that’s the one I meant! Typo on the date – changed now.

  4. Bob Crozier

    Hey Bob,
    Do you know if there any plans to take pictures from the Moon during the eclipse? Are there any pictures of this in existence already? We have had vehicles orbiting the Moon and on the Moon for years, maybe there are pictures of that already. But with the Chinese lander up there still active, this would be, I should think, a good opportunity to get good quality pictures of a solar eclipse from the perspective of the surface of the moon. It would be pretty cool to actually see that ring of fire through Earth’s atmosphere!
    Live ready!

  5. Daniel Ovadyah

    Shalom AstroBob!

    I love your web site/blog!

    It’s too bad we won’t be able to see the eclipse!

  6. Kelly

    Also, on the subject of lunar tetrads, I’ve read Jean Meeus’s “Astronomy Morsels” books (I think there are five volumes now) and one of the things he discusses is the 550-600 year eclipse cycle that was noticed by tetrads being common for two or three centuries at a time, and then three or so centuries of none at all. He’s also noticed how other eclipse patterns often follow that cycle – like how the number of total penumbral lunar eclipses and “grazing” total or annular solar eclipses (like the non-central annular that happens later this month where part but not all of the ant/umbra reaches the earth) are correlated with the number of tetrads in an era, and how the number of near-“perfect” eclipses (i.e. lunar eclipses where the moon passes almost straight through the center of the earth’s shadow and solar eclipses that occur almost overhead at greatest eclipse) and the number of “duos” (two solar or two lunar eclipses in the same eclipse season) are anti-correlated with the tetrads.

    1. astrobob

      It’s a fascinating topic. I know that the previous few centuries before the 20th there were no tetrads.

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