SAFE VIEWING TECHNIQUES
BEST WAYS TO SEE THE TRANSIT OF VENUS
To observe the transit of Venus directly you must protect your eyes at all times with proper solar filters. However, do not let the requisite warnings scare you away from witnessing this rare spectacle. You can experience the transit of Venus safely, provided you use proper eye protection.
BEST WAYS TO SEE THE TRANSIT OF VENUS
1. As suggested in the safety guidelines above, the use of eclipse shades will permit a large number of people who do not have specialized equipment to observe this event. However, as the planet approaches the limb of the sun, subtleties like the "black drop" effect will not be discernible. At one minute of arc in size, Venus is near the visual limit of most people's eyes. It's tiny compared to the sun, which is about 32 arc minutes in diameter.
Eclipse Shades or Solar Shades appear similar to sunglasses, but they have a special filter that permits safe viewing if the filter is in new condition. Before looking at the sun, inspect the material to make sure the lenses are not scratched or compromised in any way. If so, discard the shades.
Do not be lulled into thinking that you can look safely at the sun while wearing sunglasses, for sunglasses do not protect your eyes sufficiently. So don't try it!
Do not try to view the sun directly with the naked eye or through any questionable medium. These children, depicted on the April 28, 1883, cover of Harper's Weekly, are at risk of serious eye injury. They are using smoked glass, which is not sufficient.
Eclipse Shades or Solar Shades appear similar to sunglasses, but they have a special filter that permits safe viewing if the filter is in new condition. Before looking at the sun, inspect the material to make sure the lenses are not scratched or compromised in any way. If so, discard the shades.
Do not be lulled into thinking that you can look safely at the sun while wearing sunglasses, for sunglasses do not protect your eyes sufficiently. So don't try it!
Do not try to view the sun directly with the naked eye or through any questionable medium. These children, depicted on the April 28, 1883, cover of Harper's Weekly, are at risk of serious eye injury. They are using smoked glass, which is not sufficient.
2. Projection Method is a safe, indirect viewing technique for observing an image of the sun. While popular for viewing solar eclipses, pinhole projectors suffer from the same shortcomings as unmagnified views when Venus approaches the edges of the sun. Small features like the 'black drop' effect will not be discernible.
You may project a magnified view of the sun through a reflector telescope or binoculars onto a white surface, which conveniently allows a larger number of people to watch concurrently.
The projection technique sometimes has its own limitations. Because magnified projections usually have an exposed focal point beyond the eyepiece, a bystander can inadvertently put her eye or body in the sight line of the sun. Hence, a projecting telescope must not be left unattended. Large reflector telescopes can generate too much heat by concentrating a lot of the sun's energy on the secondary mirror and eyepiece, so the incoming light must be attenuated first. This technique is quiet safe if observed carefully.
You may project a magnified view of the sun through a reflector telescope or binoculars onto a white surface, which conveniently allows a larger number of people to watch concurrently.
The projection technique sometimes has its own limitations. Because magnified projections usually have an exposed focal point beyond the eyepiece, a bystander can inadvertently put her eye or body in the sight line of the sun. Hence, a projecting telescope must not be left unattended. Large reflector telescopes can generate too much heat by concentrating a lot of the sun's energy on the secondary mirror and eyepiece, so the incoming light must be attenuated first. This technique is quiet safe if observed carefully.
3. The transit of Venus is perhaps best when viewed directly when magnified, which demands an appropriate solar filter over the large end of the telescope. Often made of glass or Mylar, these "white light" filters block about 99.99% of the incoming sunlight, which allows the eyepiece then to magnify the image. A filtered, magnified view will show the sun (either blue or orange), the planet Venus, the "black drop" effect, and sunspots.
The sun's immense energy must be drastically reduced before it enters the telescope. Do not use small filters that fit over the eyepiece (as found in some older, cheaper telescopes), for the concentrated sunlight can shatter them.
Remove unfiltered finder scopes so they are not inadvertently accessed. Do not rely on a lens cap--even if it is taped on--to keep the eyes of a prying person at bay.
Special telescopes with built-in hydrogen-alpha filters show additional solar features, such as the sun's surface granulation and prominences extending outward into space. Though more expensive than traditional telescopes, they offer wonderful views of the magnified sun not seen by astronomers in previous centuries.
The sun's immense energy must be drastically reduced before it enters the telescope. Do not use small filters that fit over the eyepiece (as found in some older, cheaper telescopes), for the concentrated sunlight can shatter them.
Remove unfiltered finder scopes so they are not inadvertently accessed. Do not rely on a lens cap--even if it is taped on--to keep the eyes of a prying person at bay.
Special telescopes with built-in hydrogen-alpha filters show additional solar features, such as the sun's surface granulation and prominences extending outward into space. Though more expensive than traditional telescopes, they offer wonderful views of the magnified sun not seen by astronomers in previous centuries.
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