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Although heavy clouds blanketed the skies over Greater Sudbury for most of the evening June 5, they cleared up enough to allow a view of a rare astronomical phenomenon called the transit of Venus.
A transit of Venus occurs when the planet Venus passes directly between the Sun and the Earth. During these events, Venus can be seen from Earth as a small black disk moving across the face of the Sun.
A group of people interested in observing the transit gathered outside of Science North, where they had a chance to watch the phenomenon through telescopes and special glasses.
“It was cloudy at first, so we missed the very beginning,” Simon Strasser, a Science North staff scientist who has a doctorate in astronomy, said.
“About 15 or 20 minutes into it, it cleared up really nicely. We had 45 minutes to an hour of very clear viewing ... I think everybody left satisfied.”
Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years.
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Amateur astronomers Bob and Brenda Ulrichsen travelled to Batchewana Bay, Ont. to observe the transit of Venus. Supplied photo.
Strasser said he was quite excited to observe the phenomenon, especially given that bad weather prevented him from watching the last transit of Venus.
“It's an event you can look forward to for a whole lifetime,” he said. “I missed the last one eight years ago, so I knew this was my chance.”
 
The next transits of Venus will be in December 2117 and December 2125, meaning it's unlikely that anyone alive today will ever see another one. However, Strasser said he hopes his grandchildren will be out watching them.
Strasser said the transit of Venus was first observed in 1639 after being predicted by astronomer Johannes Kepler.
In later transit events, sailing ships were sent around the world to observe it. The phenomenon starts at slightly different times in different places on Earth, which allows astronomers to measure the size of the solar system.
“If you measure that time difference accurately, it allows you to determine the distance between Venus and Earth,” Strasser said. “Based on that distance, you can determine all the distances in the solar system.”
Because of the cloudy weather predictions, local amateur astronomers Bob and Brenda Ulrichsen travelled to Batchewana Bay, Ont. to observe the transit of Venus.
They also watched the last transit of Venus in 2004 – in that case, they were in London, Ont., to attend a university graduation ceremony later that day.
Although a few clouds threatened to block their view at times, Bob managed to take many photos of the phenomenon.
“Amateur astronomers really enjoy any event that is out of the ordinary, such as two or three planets coming close together, big, big sunspots, comets and so on,” he said.
“This is a real and important event. In this case, it won't occur again for over 100 years. It's really neat to see it.”
As for the historical importance of transits of Venus, Bob said he feels lucky to have been alive to observe two of them. He pointed out that his father, Eric Ulrichsen, never had the opportunity to observe one, as he was born in the early 1900s, and died in the 1980s.
Posted by Arron Pickard 
