This is the gear you need to view the upcoming solar eclipse
On August 21, North America will experience the first total solar eclipse visible across the continent in nearly a century. It may seem wacky. But this period of semi-darkness is an important time to practice sun safety.
During an eclipse, you won't want to tear your eyes away from the show. But staring directly at the sun can lead to solar retinopathy. That's a condition where light floods the eye's retina. In 1999, 45 patients visited an eye clinic in Leicester, England. This was after viewing a solar eclipse without proper eyewear. About half of the patients suffered from eye pain. The others reported impaired vision. These eclipse watchers were not totally blinded. But several had long-term damage.
The United States hasn't seen a total eclipse since 1979. That one only passed over a small part of the Northwest. This year, more than 500 million people in North America will be able to see at least a partial eclipse. Those within a 70-mile wide path between Oregon and South Carolina will witness a total eclipse.
A partial eclipse occurs when the moon blocks part of the sun. A total eclipse is when the moon completely blocks the sun. "Totality" is the part of the total eclipse when the sun is completely covered. It lasts only around two minutes.
To view the solar eclipse, you'll need proper gear. It may seem odd to don protection in the semi-darkness of a partial eclipse. But staring at the sun can cause retinal injury. The only time it's safe to look at the sun without protection is during totality. Keep your equipment on hand. Put it back on when the sun starts to reappear.
Eclipse glasses and handheld viewers
Eclipse glasses look like hybrids of 3-D movie glasses and sunglasses. These glasses have the added protection of a solar filter. Sunglasses only block UV rays. But eclipse glasses also cut off visible light.
If you're a casual observer or part of a large group, you'll like these glasses - low prices and bulk packaging. You can buy a pack of five paper glasses from Rainbow Symphony for around $12. If you want a sturdier option, try these plastic glasses from American Paper Optics. TSE17 has a $5.05 stars-and-stripes five-pack. American Paper Optics features everything from Bill Nye glasses to astronaut-themed frames.
Looking for something between basic glasses and high-tech binoculars? Check out this handheld viewer from Celestron. For $9.95, you'll receive two viewers with 2x magnification capabilities and a pocket eclipse guide.
Binoculars and telescopes
Binoculars and telescopes are pricier than eclipse glasses and handheld viewers. But they can be worth the money. They feature a higher magnification. But higher magnification results in a shakier image. As power goes up, the equipment becomes more sensitive to its holder's hand movements.
Binoculars are rated with two numbers. The first number is the magnification. The second is the aperture. That's the diameter of the front lens. It is measured in millimeters. The bigger the aperture, the better. But bigger lenses also mean heavier equipment.
The following options offer a range of viewing strengths. Celestron's EclipSmart binoculars feature non-removable solar filters. You'll only be able to use them for solar viewing. A 10x25 pair (10x magnification and 25mm aperture) costs around $35. A 10x42 pair costs just about twice as much. A cheaper option is Lunt's mini SUNocular. A 6x30 pair costs $29.95.
If you prefer binoculars with removable solar filters, Meade has a $69.99 10x50 pair. They work for both solar viewing and nighttime stargazing. Once you remove the solar filters, the binoculars will operate like a normal pair.
Telescopes offer some of the best eclipse views. But advanced models cost more. A basic lightweight option is the Explore Scientific Sun Catcher 70mm telescope. It costs $59.99. It can be used during both the day and night. A more advanced option is the $99.95 Celestron EclipSmart telescope. It offers 18x magnification. It has a 50mm aperture and non-removable solar filters.
Another choice is the Meade EclipseView telescope. The cheapest model is a $79.99 82mm reflecting telescope. It is designed for on-the-go use. A sturdier long-term bet is the 76mm reflecting telescope. It costs $129.99. Both models feature removable solar filters. Both are suitable for solar and nighttime use.
Add-on solar filters
Another category of eclipse viewing gear is add-on filters. These can be attached to binoculars, telescopes and cameras not originally designed for solar viewing. They are mainly used by experienced observers. Similarly to eclipse-specific gear, add-on filters prevent retinal damage.
Rainbow Symphony sells black polymer and silver Mylar filters starting at $19.95. Thousand Oaks Optical and Orion offer higher-end filters ranging in price from $22 to $150-plus.
If you want to view the eclipse without spending money on special equipment, you're in luck. Stand with your back to the sun. Use your hands, a hole-punched index card or even a patch of leaves to create a tiny opening. As sunlight flows through the empty space, an image of the sun will project onto a nearby surface. For more detailed instructions, visit the American Astronomical Society's pinhole projection page.