Folks Watching Venus Transit From Wes Observatory

Update: 7 p.m.

Dozens are gathered at the Wesleyan University Van Vleck Observatory with their telescopes to try and glimpse the transit of Venus through Middletown's mostly cloudy skies. Roy E. Kilgard, research assistant professor of astronomy at Wesleyan says a couple hundred people stopped by.

"We didn't have any breaks in the clouds, but still had a lot of fun," he said.

Earlier version:

Tuesday afternoon, folks at 's astronomy department were hopeful the cloud cover will dissipate enough this evening to allow people to see the rare celestial phenomenon — the transit of Venus.

If you miss the viewing, you won't likely catch another chance — the next one will be in December 2117.

To see live streaming video of the Venus Transit, see here or here. The Huffington Post is also live streaming it here.

Roy E. Kilgard, research assistant professor of astronomy at Wesleyan, says that historically, transits of Venus were incredibly important.

"It was through observations of Venus transits that people were first able to determine the scale of our solar system. Prior to the Venus transits in the 17th century, the distances between the Sun and all the visible planets were known only relative to the Earth-Sun distance (the Astronomical Unit) but that distance itself was not known," Kilgard says. "The first real calculation of the Astronomical Unit was made possible by observations of the Venus transit in 1639. These measurements were refined by observations of Venus transits in the 1760s and 1870s/80s."

These days, he says, transits of Venus are not astronomically useful, but are interesting for their rarity and historical significance.  

"However, the basic methodology of transit observations has been extended to observing planets orbiting other stars. It is through observations of those transits that astronomers have discovered and calculated the sizes of hundreds of previously unknown planets, with more discovered every day. By observing transits of these extrasolar planets, astronomers can also determine if those planets have atmospheres and, if so, maybe even determine their compositions," Kilgard says. 

One of the leaders in this field is Seth Redfield of the Wesleyan astronomy department.

One group of astronomers is going to be observing the transit in a very unusual way, Kilgard says. "They will be using the Hubble Space Telescope to observe the Moon! The Moon shines in reflected sunlight, and the light from the Sun should dim by a *tiny* amount as Venus passes in front of it from our perspective.  

"These astronomers are hoping to detect that little dimming of sunlight in the reflection off the Moon, and maybe even detect the signature of Venus's atmosphere. This is interesting because it's analogous to how astronomers observe extrasolar planet transits.  

"We cannot resolve planets as they pass in front of other stars — all we can see is a tiny dimming of the star's light as the planet passes in front. So these astronomers will be observing a transit in our solar system as if it were happening in a distant solar system. Information on this can be found here.

Safety is important when watching tonight's transit, Kilgard says. "One should never look directly at the Sun. At the Van Vleck Observatory, we will have telescopes that are equipped with special filters for safely viewing the Sun.  If the weather clears up, we will be able to see Venus pass in front of the Sun.  It will look like a small, black disk passing across the face of the Sun."

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He offers a picture of the 2004 transit that's comparable to the quality Wesleyan can achieve from its telescopes here.

Even if the weather is cloudy, Wesleyan will still hold a celebration of Venus with live video streams of the transit in the observatory classroom, and a collection of rare books from the Special Collections and Archives at Wesleyan's Olin Library with information about the 18th- and 19th-century transits of Venus.

The transit starts just past 6 p.m., and the observatory will be open beginning around 5:30 p.m. and running until 8:15 p.m. Information on parking can be found here.