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Once in a Lifetime: Transit of Venus!

June 4th, 2012

2004 Transit of Venus. Photo credit: Jan Herold via Wikimedia Commons

A worlwide event is happening tomorrow that will only probably happen once in your life, and you could be part of it. The planet Venus is going pass directly in front of the Sun!

It’ll be visible in pretty much all of North America and much of the world (see map below). It starts at 3 pm West Coast time in the U.S. on Tuesday, June 5th and into June 6th. The whole “transit” lasts 6 hours but you might only be able to see it until the sun sets where you are. In New York, for example, it’ll be visible for just over 2 hours.

Exciting.  BUT DO NOT GO OUT AND LOOK INTO THE SUN. Never ever. Not even with sunglasses.  You could permanently damage your eyes or go blind!

Courtesy: NASA

Call your local planetarium to see what they might have available for you to see it with. Click on the’s eye safety page  for safe viewing tips and ideas. Make a quick and easy pinhole projector from a box and some tin foil by clicking here . Or make an easy  eclipse viewer from a piece of paper and some tin foil.

You can watch a simulation of the transit below:

You’ll also be able to watch it live via the Internet from NASA’s location in Hawaii by clicking here . That’s pretty amazing considering they’ve only had telescopes for 6 transits, according to NASA. And though there were telescopes by the 1761 and 1769 transits, scientists were sent all over the world on land and by boat to observe it from different places so they could compare notes and make calculations.

Famously, Guillaume Le Gentil traveled from France all the way to India a year ahead of the 1761 transit to see it. But because of delays he was stuck on a boat being tossed by waves when it happened — not where you want to be trying to make precise measurements, so that was a bust. He went to India anyways determined to catch the next one 8 years later. You can’t be more prepared than that! Unfortunately, a cloud passed right in front of the Sun as Venus was about to transit — and stayed there almost the entire three hours. Talk about bad luck! (You can read more about it in Bill Bryson’s great book for Kids, A Really Short History of Nearly Everything ).

The transits were significant back then because scientists predicted they could use it to measure the distance between the Earth and Sun — 93 million miles. And they were surprisingly accurate! That’s pretty amazing considering there weren’t any computers or calculators back then, and certainly no measuring tape even remotely long enough! And once they figured out that measurement, they could use it to calculate how big our solar system is and the distances of other planets. It really helped us understand the scale of space and our place in it. So, how’d they do it? You can get an idea by watching this NASA video (starts part way in).

So, why’s the world all abuzz about this now? First, it won’t happen again for another 105 years so it’s a very rare event. Strangely, it happens in pairs — once, and then 8 years later — and then not again for over a century. The last time was in 2004, but you were probably too young to be aware of it. So, this is it.

Also, this time, the Hubble Space Telescope will be looking at Venus’s reflection in a crater on the Moon (actually using the crater kind of like a projection screen because even the Hubble Telescope can’t look directly into the Sun).

Studying the reflection of Venus on the Moon could help us understand whether a recently discovered planet 600 light years away, Kepler 22-b (read HTE’s story about its discovery here) , may have (or had) water on it, which could lead us to believe that some form of life exists, or once existed, on it. That could be a big deal.

Venus is the second planet from the Sun. Mercury (the planet closest to the Sun), and the Moon, also orbit between the Earth and the Sun, so why is Venus’s transit so special? Jason Kendall, HTE’s Space Writer and NASA Solar System Ambassador says it’s because Mercury’s orbit is more unpredictable and the Moon’s angle isn’t quite right. Venus’s, by comparison, is great.

Oh, and why’s it called a “transit” and not an eclipse? Jason says it’s because Venus looks small passing in front of it and has to travel, or transit. When the Moon goes in front of the Sun, it looks like it’s covering most or all of the Sun — eclipsing it.

HTE’s Space Writer, Jason Kendall, contributed to this report.

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