Anticipating Wednesday’s Awesome Lunar Eclipse

Watch for a ruddy moon in Pisces the Fish during the total lunar eclipse which happens Wednesday morning October 8th. The moon’s color can range from dark brown to coppery red depending on the transparency of the Earth’s atmosphere as described below. This map shows the view at the start of total eclipse as seen from the Midwest. Source: Stellarium

If you missed last April’s total lunar eclipse because of weather or commitments, you’ve got a second chance Wednesday morning October 8th. This is the final total lunar eclipse of 2014 and the second of four in a series called a tetrad – four consecutive total eclipses occurring at approximately six month intervals this year and next.

On Wednesday morning October 8, the moon will slide into Earth’s shadow and we’ll be treated to a total lunar eclipse. The outer shadow or penumbra only lightly shades the moon; for most of us the eclipse begins when the moon touches the inner, darker shadow called the umbra. Times are shown for each stage of the eclipse. Add one hour for EDT, subtract one hour for MDT and two hours for PDT. Credit: NASA / F. Espenak with additions by Bob King

“The most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA,” says longtime NASA eclipse expert Fred Espenak.

This eclipse happens during the early morning hours, so North American skywatchers will need to remember to set their alarm clocks. In the Midwest, partial eclipse begins at 4:15 a.m., when the moon’s eastern limb eases into Earth’s umbral shadow.

World map showing where the eclipse will be visible. Most of North America and much of Asia and Australia will see the event. Those living in the western half of the U.S. will see the eclipse from beginning to end. Farther east, the partially eclipsed moon sets at sunrise. Credit: NASA / F. Espenak

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.

Animation showing the moon’s passage through the penumbra and umbra during the upcoming total eclipse. Credit: Tom Ruen

A lunar eclipse is divided into stages beginning with the moon’s entry into the penumbra. Most of us won’t notice any shading on the moon until it’s well inside the outer shadow about a half hour before partial eclipse begins. Look for a subtle darkening along its eastern edge.

During a lunar eclipse, the sun, Earth and moon are neatly lined up in space. For a few hours, the orbiting moon passes through Earth’s shadow and we experience a lunar eclipse. Credit: Starry Night

Because the Earth is a solid object, it casts a shadow in sunlight just like you and I. A lunar eclipse occurs when the sun, Earth and moon are precisely lined up in a row at the time of full moon, and the moon moves into Earth’s shadow.

Although the moon’s doing all the moving, it looks like the shadow is encroaching on the moon, slowly devouring it nibble by nibble. When the moon’s about half covered you’ll notice that the shadowed half is deep red or orange.

Artist view of Earth totally eclipsing the sun as viewed from the moon. Low angled sunlight filtered by our atmosphere is reddened in exactly the same way a setting sun is reddened. That red light bathes the moon’s surface which reflects a bit of it back toward Earth, giving us a red moon during totality.

Sunlight filtered and bent by Earth’s atmosphere spills into the umbral shadow and colors the moon a coppery red, burnt orange or rust. You can picture why this happens by pretending you’re standing on the moon looking back at Earth during total eclipse.

From your new perspective, the Earth passes in front of the sun, ringed by a glowing, red-orange atmosphere. Our atmosphere bends or refracts the light from all the sunrises and sunsets around the planet’s circumference into the umbra, adding color to the moon.

Depending on the amount of suspended particles called aerosols in Earth’s atmosphere at the time, the moon’s disk can glow a bright copper orange to deep brown-black. The more particles and haze, the greater the light absorption and darker the moon.

For the East Coast, totality begins during bright twilight with the moon low in the western sky. Skywatchers in the central U.S. will see all of totality and most of the final partial phases before moonset. If you live in the western U.S. you’ll get to watch the whole shebang in a dark sky.

Mid-eclipse is when the moon is deepest in Earth’s shadow. Since the top or northern end of the moon is closer to the shadow’s edge, it should appear noticeably lighter than the bottom half, which lies closer to the center.

The moon in mid-eclipse during the last total eclipse on April 14-15, 2014. You’ll notice a lot of variation of light and color across the disk. Credit: Bob King

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.

Besides the pleasure of seeing moon change color like a quickie version of fall, watch for the sky to darken as totality approaches. Eclipses begin with the sky flooded in bright moonlight nearly barren of stars. During totality, all the stars come back in a most breathtaking way. Be sure to sweep your gaze east to enjoy great views of the winter constellations including Orion.

A rare treat greets anyone with a pair of binoculars during next Wednesday morning’s total eclipse. The planet Uranus will sit a little more than one moon diameter to its southeast during totality. This view shows the scene from the U.S. Upper Midwest at 5;30 a.m. Source: Stellarium

By good fortune, the eclipsed moon will lie only about 1/2° west of the planet Uranus which should be easy to spot in binoculars during the hour of totality. Speaking of which, binoculars are a great way to enjoy the eclipsed moon. Somehow they give it a more three-dimensional look. Colors are richer and you’ll see the lunar disk suspended among the stars, a rare sight.

For your latest forecast, click HERE. I’ll have more information for you early next week including links for watching the eclipse on the web and photo tips. Stay tuned!

11 Responses

  1. Troy

    I’m wondering if this eclipse series will be a true tetrad, because according to my software it says the April 2015 lunar eclipse only covers 99%. I have seen it variously described as partial and total as well.
    If I have clear weather this should be a very cool eclipse. The eclipsed moon will quickly set on the horizon, and fortunately I’ve got a great site to photograph it. I’m hoping for some horizon distortion and a cool eclipsed moon illusion (naked eye only).

      1. Kelly

        Different eclipse prediction sources may use different factors for the effects of the earth’s atmosphere and oblateness; normally it makes little difference, but in cases like this one being on the threshold between eclipse types can make a difference on the classification. (Next time we have one of these borderline situations is with the August 2016 new moon – some sources say an extremely small – and completely invisible – penumbral eclipse occurs while NASA and others show no eclipse. No practical difference for us either way.)

        For next spring’s event whether we see a very shallow totality or a speck of sunlit moon at maximum eclipse may depend on the weather conditions at what would be the northern limb of the earth from the moon – which if I’m correct is roughly northern Canada (being right after the March equinox the northern end of the earth as viewed from the ecliptic plane veers toward the morning side of the planet). If it’s cloudy, especially with high-altitude clouds there, that favors a total-like appearance. On the other hand if it’s clear there some direct (albeit atmosphere-filtered) sunlight may reach the least eclipsed part of the moon. Regardless it’d be a sight worth seeing!

        (Since the moon has essentially no atmosphere and is closer to a perfect sphere than Earth we don’t have to account for such factors with solar eclipses, although the mountains and valleys along the moon’s limb are usually factored in.)

  2. Brian

    Thanks for the “heads up” on this eclipse.

    Have you ever thought about publishing an astronomy wall calendar? The astronomy wall calendars I’ve been getting for the past several years (“Astronomy 2014”) that are “edited by Terence Dickinson” and publised by Firefly Books have gotten worse and worse. In past years, the calendars listed upcoming events and occasionally some of the dates were wrong (examples: a new moon and a full moon only a week apart, or a major event in the wrong month). Now it only lists historical events. In addition, they keep printing the same trivia year after year. So, I’m looking forward to buying “Astro Bob’s 2016 Astro-Calendar” next year!

    1. astrobob

      Hi Brian,
      I hadn’t thought about it but I like your enthusiasm for the idea. Too bad the Firefly calendar appears to be headed downhill.

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