In last month’s Sky Talk column we gave an overview of the total solar eclipse that will occur on August 21st. Again, this is nature’s grandest spectacle—baring none! It’s recommended that you review that installment before reading further.Here we discuss the important viewing precautions needed to experience this event safely. August’s magnificent celestial spectacular is not to be missed. But you must exercise care in watching it. Looking at the Sun through even the darkest pair of sunglasses will not protect you. They may filter its visible light, but harmful ultraviolet and infrared rays will still get through. One traditional recommendation is using a #14 welder’s filter. Better and much more convenient is an inexpensive and safe pair of Eclipse Shades similar in construction (only!) to the 3-D glasses being used in theaters. These are ideal for safely looking at the Sun with the unaided eye anytime and checking for the occasional large sunspot.
In using binoculars or telescopes to view the eclipse, 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 a telescope or both binocular lenses and NOT over their eyepieces. Many inexpensive small telescopes (especially imported ones) 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.
Another safe but not as effective way to view the eclipse is to project the Sun’s image through a pinhole in a piece of cardboard and onto a white sheet of paper. The projected image will be quite small, but depending on the hole size and how far back the screen is placed it should nicely reveal the Sun during the partial eclipse phases leading up to totality. A similar scheme called “eyepiece projection” is sometimes used with telescopes themselves but has been known to crack eyepieces if prolonged too long. And here, as any time a telescope is being used for solar viewing, its finder scope must also be capped since it too can cause damage! Totality itself can be viewed directly without filters, but the instant it ends you must immediately go back to a filtered view!
The last total eclipse of the Sun to cross the United States was in March of 1970. Along with a party from Pittsburgh’s Buhl Planetarium, we flew to Virginia Beach, Virginia, to witness it. Standing on the beach by the ocean, we saw the Moon’s dark shadow sweep toward and then engulf us during totality for nearly 3 minutes, before finally heading out over the Atlantic Ocean. Many people have remarked that a total solar eclipse is a spiritual event. Every one of us in our party certainly agreed! I still remember the gasps and cries of delight at the instant of totality. And here, a personal word of advice: forget picture-taking and simply enjoy the spectacle! (I personally know of people who traveled—sometimes at great expense—to one of these events but who never actually saw the eclipse itself directly because their eye was behind a camera. How very unfortunate.)
For future planning, there will be two more total solar eclipses visible from the United States this century. The first occurs on April 8th, 2024, and will be seen essentially across the central and eastern half of the country from Texas to Maine. The second is on August 12th, 2045, and will be visible across the lower half of the continent from California to Florida.
— 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.
