Tomorrow is the big day. Time to dust off your eclipse glasses, binoculars and posterboard, or pinhole camera and witness the transit of Venus, a once in a lifetime event! (Actually, it's a twice in a lifetime event, but if you missed it eight years ago, this is your last chance!) To help prepare, I reached out to Phil Plait, the "Bad Astronomer." He gave me the inside scoop, including how and when to witness this rare astronomical occurrence. He also filled me in on its historical significance and how it may help astrophysicists learn more about planets outside of our own solar system. To learn more, watch the video above and/or read the transcript below. And don't forget to tell me your experience by leaving a comment at the bottom of the page. Talk nerdy to me!
PHIL PLAIT: The transit of Venus is a relatively rare astronomical phenomenon, where Venus the planet which orbits the sun closer than the Earth gets directly between the sun and the Earth. And so we see it literally moving across the face of the sun, it's like a little mini eclipse.
CARA SANTA MARIA: Hi everyone. Cara Santa Maria here. And that's Dr. Phil Plait, author of the book "Death From The Skies!" and the "Bad Astronomy" blog. I reached out to him to learn more about the transit of Venus, which takes place tomorrow (Tuesday, June 5th, at least for those of us in North America). In case you missed it last time, in 2004, I recommend you don't let that happen again.
PP: The next transit of Venus isn't until December 10, 2117. So if you don't see this one, you're not going to get another chance for over a century.
CSM: Hard to take in rare astronomical sights when you're dead. So, why is this event so infrequent? And why does it occur in pairs, with eight years between them?
PP: The reason that we don't see a transit every time Venus goes around the sun is because its orbit is tilted a little bit with respect to the Earth. So sometimes even though it's getting in between us and the sun, it's not directly in between us and the sun. It misses, but every century or so our orbits will line up just right and Venus just cuts a chord across the face of the sun, and then eight years later it's moving a little bit and it cuts across again, but then the orbits don't line up again for another century. So these come in pairs eight years apart, separated by well over a hundred years.
CSM: And more than just a once (well, twice)-in-a-lifetime opportunity to see something really cool, it's actually taught us a lot about our own solar system.
PP: Three hundred years ago, we didn't know exactly how far the planets were from the sun; we only knew relative to the Earth. So we knew Venus was like, point-5, point-7 times the Earth's distance from the sun. By observing these transits, and by timing them exactly on different spots on the Earth, they could calculate how far away the Earth was from the sun.
CSM: And now, we can use similar techniques (with much more sophisticated technology) to look for exoplanets.
PP: It's kind of like what we're doing now to look for planets orbiting other stars. If the planet orbits the other star at just the right angle we see it pass directly in front of the star and if we measure the star, like we make a little plot of the starlight, it dips and then goes back up as the planet goes across, that's precisely what we're seeing here. So to model this, to understand it better, astronomers are going to be observing this Venus transit in various and kind of weird ways to see how this affects our observations of transiting planets orbiting other stars.
CSM: Now, don't just take our words for it. See it for yourself! Venus will be transiting the sun for roughly seven hours. If you live on the East Coast, it'll start at about 6 p.m. and end around 1 a.m. For different time zones, calculate accordingly. Obviously, the sun has to be in the sky to see the transit, so those of you living in Hawaii and Alaska are going to have the best viewing conditions. And just like an eclipse, whatever you do, don't look directly at the sun during the transit without proper protection! It really can cause blindness or severe eye damage.
PP: What I would recommend is looking up and seeing if there is a planetarium, an observatory, or a local astronomy club where you live, and they will probably have things set up correctly. You could also have eclipse glasses. These are glasses I got for the May eclipse. I can't see anything now through these, they're very, very dark. These are actually rated safe, but you can't just use sunglasses or something like that because that can let through a dangerous amount of radiation. Your best bet if you don't have somebody nearby, if you have binoculars, hold them up to a piece of paper and project the image of the sun onto the paper--that's safe. You can do the same thing with a telescope, you can make a pinhole camera. You can find instructions on that all over the Web. These are all safe ways of observing this, and I recommend that you do, because it's pretty slick.
CSM: To learn more about the transit of Venus, visit transitofvenus.org or Phil's own website, badastronomy.com. And of course, check out our coverage here on HuffPost Science. Don't forget to reach out to me on Facebook, Twitter, or leave a comment right here at the bottom of the page. Come on, talk nerdy to me!
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First Posted: 06/04/2012 7:42 am Updated: 06/05/2012 5:25 pm