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coming soon, twice in our life-time – a venus transit

The last time the planet Venus was seen passing across the disk of the sun – a Venus transit – was in 1882. Transits across the sun are possible only with Mercury and Venus, the two planets with orbits closer to the sun than the Earth. Mercury has an average of thirteen passages every century, but transits of Venus occur in pairs at more-than-century intervals.

From the NASA Eclipse site:

“The entire event will be widely visible from the Europe, Africa and Asia as shown in the map in Figure 1 ( Low Res or High Res). Japan, Indonesia, the Philippines and Australia will witness the beginning of the transit but the Sun will set before the event ends. Similarly, observers in western Africa, eastern North America, the Caribbean and most of South America will see the end of the event since the transit will already be in progress at sunrise from those locations.”

The NASA link also gives links to details of when and where in the sky observers in different locations may see this event.

This British site gives, with diagrams, a detailed explication why Venus transits occur so infrequently, and in pairs often 8 years apart.

WARNING

Remember, NEVER look directly at the sun with the naked eye or, even more foolishly, through a simple telescope or binoculars. You must use appropriate and adequate safety equipment, such as solar filters, or appropriate viewing methods.
It is not possible to improvise and it is dangerous to try. Obtain advice from your local optical suppliers or astronomy club.

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© abelard, 2004, 14 may


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