Wow! What a month for celestial spectaculars—a total eclipse of the Moon (for those who were clouded out at the one in April) and a partial eclipse of the Sun just two weeks later! Both will be readily visible to the unaided eye and thrilling sights in binoculars and small telescopes (given proper safety precautions in the case of the Sun).
The first of these events begins with the left edge of the full Moon entering the Earth’s dark inner shadow (the “umbra”) at 5:14 a.m. EDT on October 8 and continuing to become ever-more fully immersed in it for the next 70 minutes. Totality itself will occur at 6:24 a.m. and last exactly an hour, after which the Moon begins to slowly emerge from the cone of darkness at 7:24 a.m. in reverse order. But for sky-watchers in the eastern part of the country, dawn will be growing bright well before then and the Moon will be setting in the west while the eclipse is still in progress. Those further west will be able to see the entire event including the partial phases as the Moon leaves the Earth’s shadow.
There are several interesting things to notice as you watch this event unfold. Most obvious are the darkness of the eclipsed Moon and the range of colors displayed, both of which vary from one eclipse to another. These depend on the clarity of the Earth’s atmosphere at the time, which refracts or bends sunlight around and into the umbral shadow. There have actually been eclipses so dark that the Moon remained all-but invisible during totality—and ones so pale that you had to look carefully to see that there was even an eclipse in progress! Among the colors that have been seen are shades of reddish-orange, brown, copper, rose, and even blood-red. Notice, too, that the Earth’s shadow is curved at all phases of the eclipse, as the Moon passes through it. This is direct proof that the Earth itself is round—something recognized by many ancient sky-watchers. And finally, realize that you’re actually seeing our lovely satellite move eastward in its orbit—as it first passes into, through, and then out of the shadow at roughly its own diameter each hour.
The second eclipse involves the Sun on the late afternoon of October 23. It’s a partial eclipse (as opposed to a total one) and favors observers in the west. In most of the eastern half of the U.S. and Canada, the eclipse will still be in progress as the Sun sets. Those on the west coast will see the entire event unfold before sunset. The further north you are the more of the Sun that will be covered at maximum eclipse—ranging from about 40% in southern California to 65% in Vancouver. Mid-eclipse occurs around 3:30 p.m. PDT for the former area and about 3:00 p.m. for the latter one.
Our Daytime Star is a fascinating object and the only one we can see up-close. But a word of caution is in order: you must exercise extreme care in viewing the Sun! Looking at it (even partially eclipsed) through the darkest pair of sunglasses will not protect you. They may filter out most of its visible light, but harmful ultraviolet and infrared rays will still get through. One traditional recommendation is viewing it through a #14 welder’s filter. More convenient are an inexpensive and safe pair of Eclipse Shades similar in construction (only!) to the 3-D glasses being used in theaters and which are available at www.scientificsonline.com.
For up-close views, binoculars are recommended. (And since the Sun is currently at sunspot maximum, keep alert to seeing some of them.) However, proper filters are an absolute must to avoid serious eye damage or blindness! And the filters must be of the type that fit over the front of both binocular lenses—NOT over their eyepieces. (This is especially true in the case of a telescope and its finder. Many inexpensive small scopes have an eyepiece filter marked “Sun” on it. These are absolutely deadly and often crack due to the intense heat being focused by the telescope itself. Stopping most of the light and heat of the Sun before it enters an instrument is the only safe and sane way to view it directly.) One excellent source for optical solar filters is Thousand Oaks Optical. Another safe but not as effective way to view the Sun is to project its image through a pinhole in a piece of cardboard and onto a white sheet of paper. While the image will be small (depending on the separation of the pinhole and paper), it will reveal the Sun’s disk.
— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com