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Sign up. Table of Contents Subscribe Digital Editons. A chronicle of the first steps on the Moon , and what it took to get there. Within a region about kilometers on either side of the eclipse path, a partial solar eclipse is visible. The duration of totality may be only a brief instant; it can never exceed about 7 minutes.
Because a total eclipse of the Sun is so spectacular, it is well worth trying to see one if you can. As a result, eclipse chasing is rarely within the budget of a typical college student. Nevertheless, a list of future eclipses is given for your reference in Future Total Eclipses , just in case you strike it rich early.
And, as you can see in the Appendix, there will be total eclipses visible in the United States in and , to which even college students may be able to afford travel. What can you see if you are lucky enough to catch a total eclipse? A partial phase follows, during which more and more of the Sun is covered by the Moon. About an hour after the eclipse begins, the Sun becomes completely hidden behind the Moon.
In the few minutes immediately before this period of totality begins, the sky noticeably darkens, some flowers close up, and chickens may go to roost. As an eerie twilight suddenly descends during the day, other animals and people may get disoriented. During totality, the sky is dark enough that planets become visible in the sky, and usually the brighter stars do as well. The corona thin outer atmosphere of the Sun is visible during a total solar eclipse.
It looks more extensive in photographs than it would to the unaided eye. It is ordinarily not visible because the light of the corona is feeble compared with the light from the underlying layers of the Sun. The total phase of the eclipse ends, as abruptly as it began, when the Moon begins to uncover the Sun. Gradually, the partial phases of the eclipse repeat themselves, in reverse order, until the Moon has completely uncovered the Sun.
We should make one important safety point here: while the few minutes of the total eclipse are safe to look at, if any part of the Sun is uncovered, you must protect your eyes with safe eclipse glasses [1] or by projecting an image of the Sun instead of looking at it directly.
For more, read the How to Observe Solar Eclipses section of this chapter. A lunar eclipse occurs when the Moon enters the shadow of Earth. The geometry of a lunar eclipse is shown in Figure 4. Unlike a solar eclipse, which is visible only in certain local areas on Earth, a lunar eclipse is visible to everyone who can see the Moon.
Because a lunar eclipse can be seen weather permitting from the entire night side of Earth, lunar eclipses are observed far more frequently from a given place on Earth than are solar eclipses. Figure 4: Geometry of a Lunar Eclipse. Note that the distance the Moon moves in its orbit during the eclipse has been exaggerated here for clarity. If the Moon does not enter the umbra completely, we have a partial eclipse of the Moon. But because Earth is larger than the Moon, its umbra is larger, so that lunar eclipses last longer than solar eclipses, as we will discuss below.
A lunar eclipse can take place only when the Sun, Earth, and Moon are in a line. The Moon is opposite the Sun, which means the Moon will be in full phase before the eclipse, making the darkening even more dramatic. About 20 minutes before the Moon reaches the dark shadow, it dims somewhat as Earth partly blocks the sunlight.
Even when totally eclipsed, the Moon is still faintly visible, usually appearing a dull coppery red. After totality, the Moon moves out of the shadow and the sequence of events is reversed. This illustration shows the rare alignment of the Sun and Moon that casts a shadow on our planet. During a total solar eclipse , the Moon passes between Earth and the Sun. This completely blocks out the Sun's light.
However, the Moon is about times smaller than the Sun. How can it block all of that light? An illustration showing the Earth, Moon, and Sun during the August 21, eclipse. When objects are closer to us, they appear to be bigger than objects that are far away. For example, most stars in the night sky look like tiny white dots of light. In reality, many of those stars are larger than our Sun—they are just much farther away from Earth! Even though the Moon is times smaller than the Sun, it's also about times closer to Earth than the Sun is.
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