Transit of Venus! Sydney 2012 Contacts, Contracts and Parallax

[Applause] Now there are very few things that will get me out of bed in the morning before 8:00, but the transit of Venus is one of them. Because this is the last time it's going to happen in my lifetime, so I don't have to worry about this becoming a regular thing on my way to see the transit of Venus.

Okay, so the transit is probably starting right now. This is probably contact one. It's 8:16 a.m. in Sydney. My first look… oh wow! [Music] Can you see it? Absolutely not, you can't see it. Nope, it's like a black dot—that's Venus. Beautiful. The sun is now out, and with these silly glasses, you can actually see Venus on the sun.

Nowadays, I imagine most people don't get excited about Venus passing in front of the sun. I mean, what's the big deal? But in the old days, it was a really important event because it allowed us to determine the scale of our solar system and then the scale of the universe. Astronomers at the time knew the relative distances between the planets because of Kepler's laws. They could calculate the ratios of the different radii of the orbits of planets, but unfortunately, they didn't have any absolute measure. So they couldn't really say how far anything was from anything else.

Edmund Haley, the guy who the comet is named after, was the one who suggested that by timing how long it takes Venus to pass across the face of the Sun from different points on the Earth, it would allow us to measure the distance between the Earth and the Sun. That's using something called parallax. Now, to illustrate parallax, I've actually kind of set up a solar system in my kitchen and living room. So you can see the sun there behind me. This is Venus, and over here we have the Earth.

Oh, sorry guys, I got to take this—it's Destin from Smarter Every Day.

Destin: Hey Derek, you there?
Derek: Yo, what's going on?
Destin: Hey, what's up dude? Hey man, I went up to Space and Rocket Center. We got the times. You said we could calculate the distance to the sun, right?
Derek: Uh, yeah, because we're on opposite sides of the globe. We're going to compare times and calculate the distance of the Sun.
Destin: Uh, my time was 6 hours, 28 minutes, and 4 seconds in Sydney.
Derek: Okay, what time you get?
Destin: 6284, right?
Derek: 6284, that's me.
Destin: Okay, mine was 6 hours, 45 minutes, and 36 seconds.
Derek: Oh, a bit longer. All right. So do I just go put it in that calculator website you gave me?
Destin: Yeah, yeah, yeah, let's do that.
Derek: Okay. Right, sound good?
Destin: What, you mean just call you back afterward?
Derek: Sounds good. All right, talk to you later. Bye.

So the plan is I'm going to shoot from the Earth from the top of the Earth and see what it looks like when I make a transit of Venus across the face of the Sun. Then I’m going to change my perspective slightly, so I'm going to go to a lower part of the Earth, and I'm going to shoot the same thing. Then I want to overlay those two images to see how Venus looks as it’s tracking across the Sun from those two different locations. It should trace out two separate chords across the face of the Sun, and that is what allows us to estimate the distance to Venus and the distance to the Sun and everything else in this solar system.

'Cause once we have one absolute distance, we can get all of the distances. So, 243 years ago, Captain Cook was down here, sent to Tahiti to observe the transit of Venus. After that, he opened his sealed papers with his secret mission. He was meant to find the Great Southern Land and claim it for Britain, which is what he did. He mapped and explored the coasts of New Zealand and Australia before returning home. This was his first voyage to the South Pacific, so pretty exciting.

And then, in I guess kind of a related note, eight years ago when this transit was taking place, I was actually in the air over the Pacific, flying from Vancouver to Sydney to make my life here. So, you know, me and Cook, we got something in common, I guess.

Destin: Calling back with the distance. What's going on, Dustin?
Dustin: Hey, what's up dude?
Destin: Hey, I got it! I am W—it is like, it's like in the morning here or something. Anyway, it's 93 million miles.
Dustin: 93 million? No, I don't think that's a unit, is it? Miles? They got rid of that like 100 years ago—used to put man on the moon.
Destin: Wow, inches? That's awesome!
Dustin: You want it in kilometers?
Destin: I went in kilometers—how far is it?
Dustin: It's about 149 and a half and some change, million kilometers.
Destin: So that's awesome—that's like bang on!
Dustin: Oh, is it?
Destin: Yeah, is that an astronomical unit?
Dustin: That is one astronomical unit, so good observing sir!
Destin: Well done, thank you very much!

Oh, there was… hey, by the way, there was a kid there today. We did it at the US Space and Rocket Center under the Saturn V, but there was a kid there that made his own telescope out of PVC pipe.
Destin: That's awesome man! I wish I could make a telescope out of PVC pipe.
Dustin: Yeah, he told me how to do it. He ground the glass and everything—it’s pretty parabolic.
Destin: Wow, I want to check that out! So I'm going to put an annotation over to that video of Destin, so click on the iPhone here if you want to go see D's video where you can make your own telescope out of PVC.
Dustin: I want an iPhone!
Destin: Yeah, yeah, why?
Dustin: Cool, yeah, click the iPhone. There you go—click on it.

All right, you better get to bed dude. I'm going crazy!
Dustin: I do need some sleep, so I'll let you go.
Destin: All right, we'll catch you later—have a good night!