April 15 lunar eclipse
The Naval Observatory's Geoff Chester explains Tuesday morning's lunar eclipse.
WASHINGTON -- The night of April 14 provides sky watchers a great celestial double feature. Mars, the Red Planet, is closest to Earth on the 14th and at its brightest. In the hours after midnight, the full moon undergoes a total eclipse.
Bright rust-colored Mars will be visible in the southeast right after dark. It is the brightest "star" in that portion of the sky, and is kept company by the full moon and the bright blue-colored star Spica. Mars will be over 57 million miles away, but this is the closest it's been to Earth in more than six years.
Mars will remain bright for the remainder of April as the distance between our planets begins to widen. In 26 months, Mars will come close again.
In the early hours of April 15, the full moon will enter the Earth's shadow and begin the total lunar eclipse, a sky spectacle that will be visible over the entire continental U.S. and much of the Western Hemisphere. In the U.S., the last total lunar eclipse was 2011, so it's been awhile.
The moon will enter the outer shadow of our planet called the penumbra at 1:20 a.m. EDT. The penumbra is a ghostly shadow that is hard to see. Things get much easier to see when the moon enters the dark umbra shadow of our planet at 1:58 a.m. EDT to start the partial eclipse phase. You will see the curvature of our planet projected onto the moon, and as time goes on, more of it gets covered.
Things get interesting at 3:07 a.m. EDT; this is when the total eclipse phase begins and the full moon is completely immersed in the shadow of our planet. No direct sunlight falls on the full moon in this phase of the eclipse; here, we see a "copper penny" color covering the moon. It's caused by sunlight passing through the Earth's atmosphere and falling upon the moon's surface.
If you were an astronaut on the moon, you would see the darkened Earth surrounded by a ring of light along the circumference of our planet. All of our planet's sunrises and sunsets would be visible as a reddish colored ring. It is this light that we see on the Moon during the totality phase of the eclipse.
The color and its brightness that we view on the totally eclipsed moon can vary due to worldwide atmospheric conditions. The total lunar eclipses that occurred right after Mount Pinatubo erupted in the Philippines in 1992 were so dark, even in my telescope. This was due to the amount of aerosols and debris from the volcano's eruption that were placed high into the Earth's atmosphere, which blocked the passage of sunlight through our atmosphere. Scientists can measure the brightness and color of the totally eclipsed moon to glean the condition of the Earth's high atmosphere.
The halfway point of the eclipse occurs at 3:46 a.m. EDT and totality ends at 4:25 a.m. EDT. The umbra shadow of the Earth will now be seen moving off the moon and the partial eclipse phase ends at 5:33 a.m. EDT.
It doesn't take any equipment to observe the eclipse, but binoculars are a real plus in seeing the advancing Earth's shadow and the colors of totality. In a telescope, you can see craters and lunar features enveloped by the umbra and view the totally eclipsed moon in great detail. A wide view is best, but it is neat to zoom in on a feature to see what it looks like in the colors of totality.
If you do not have a telescope, you can tune in to the Griffith Observatory in Los Angeles, Calif., which will provide a live web stream. You can also click the "Griffith TV" button on the Observatory's home page.
The stream will begin at 12:45 a.m. EDT on April 14, and conclude at the end of the umbral eclipse at about 5:35 a.m. EDT on April 15.
You can take pictures of the eclipse if you have a camera and tripod. A zoom lens is a big help, but almost any camera will capture the Earth's umbra and the color of totality. Learn more here.
With this total lunar eclipse, we are beginning a remarkable series of four consecutive eclipses, or tetrad, all visible from North America. The next total lunar eclipse will be in October.
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