If you plan on watching the Transit of Venus, optometrist Dr. Shelley Geier asks that you make sure to take the necessary precautions.
Unless you plan to be around in another 120 years, Tuesday, June 5th will be your last opportunity to witness the astronomical phenomenal that is the transit, when Venus, the second planet from the sun, passes between the sun and the Earth. The last time this happened was in 2004, and it will not occur again until 2117.
Geier doesn't doubt that folks who are seriously into astronomy will have the necessary filters for their viewing apparatus. As for amateur astronomers such as herself, she warns that sunglasses or even a welding shield may not provide enough protection.
"You can actually get a solar burn if you watch the sun long enough. And this thing is going to last for a while," says Geier, adding that she sees one or two people a year who have received a solar burn of some kind. "And they are permanent. Some have vision loss, some don't. Some resolve, some don't."
A study by Dr. Ralph Chou of the Waterloo School of Optometry and Vision Science states that out of 70 cases of retinal burns that occurred in 1999 as result of people viewing a solar eclipse, 35 per cent were wearing sunglasses, 15 per cent were wearing special eclipse glasses and 50 per cent had no protection at all. The transit, Geier notes, is substantially different from a lunar eclipse as Venus appears only as a small black circle travelling across the sun.
She says the safest way to view the transit is to set a telescope or binoculars up on a stand, with a white card behind the viewing end. This way, a magnified view of the transit will be projected onto the card.
In 1761, English astronomer Edmund Halley, for which Halley's comet was named after, determined that the Transit of Venus, observed from different points on Earth, could be used to determine the Earth's distance from the sun.
For more information on the transit and how it can be viewed, visit www.transitofvenus.org.