Mark June 5th 2012 on your calendar! This is the date of the second only, and last, transit of Venus in our lifetime. It is one of the rarest regular astronomical events. A transit of Venus happens only twice within 8 years every 105.5 or 121.5 years. Another one won’t happen again until 2117!
What is a Transit of Venus? A transit of Venus happens when our closest planetary neighbour, Venus, is aligned with the Earth and Sun so closely that we see it pass in front of the Sun. Over the course of several hours observers on Earth can see the dark disk of Venus cross the Sun from one edge to the other. It is similar to a solar eclipse by the Moon, but of course because Venus appears much smaller it doesn’t cover the entire Sun. We won’t even notice a dimming of the Sunlight. Being prepared so you don’t miss this event is therefore crucial!
A transit of Venus was first predicted by the famous astronomer Johannes Kepler and observed by the English astronomer Jeremiah Horrocks in 1639. Observing the next transits in 1761 and 1769 became extremely important when it scientists realized that it could be used to determine the size of the solar system. Back then nobody knew how large the distances between planets are. From different places on Earth the transit begins and ends at slightly different times. By accurately timing this difference we can triangulate the distance to Venus. This then gives us a scale for the solar system. Captain James Cook, for example, sailed halfway around the world from England to Tahiti to observe the event in 1769. His data combined with other observations led to the first estimates of the size of our solar system.
For your only chance to see this event you need to prepare so you can do it safely. You should never look at the Sun without a proper filter. You will need special dark glasses, welding goggles, a pinhole camera, or a telescope equipped with a special solar filter. You can obtain dark glasses at http://www.canadiantelescopes.com/Astronomers-Without-Borders-Safe-Solar-Glasses_2. If you can come to Science North on June 5th we will set up several telescopes, and provide dark glasses free of charge. Our event will start at 5 PM with a presentation, followed by observing once the transit starts at about 6 PM. From Sudbury, we will unfortunately miss the end of the transit as the Sun sets.
Don’t miss this event!
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