The history behind a rare astronomical event: The transit of Venus
June 1
Doug Duncan
A very unique and rare astronomical event is going to take place June 5. It’s called
the Transit of Venus. On that day Venus passes between the Sun and Earth giving
people a chance to see the planet against the backdrop of the solar disc, something
that won’t happen again for 121 years.
CUT 1 “It’s incredibly rare and it’s incredibly fun. You’re seeing something that very
few people will ever get to see. Kind of like when I saw Halley’s comet. Halley’s
comet is not the brightest comet that there is but it’s really cool because you can
only see it once in a lifetime.” (:17)
That is Doug Duncan, director of CU’s Fiske Planetarium and a senior instructor of
astrophysics and planetary sciences at CU-Boulder. He says the event is not only
rare but it has a very important historical significance as well.
CUT 2 “The reason the transit was important in the past is that if you look at Venus
going in front of the sun from two different places on the Earth, you can use
geometry and you can figure out how far away Venus is and that was the first time
we knew the size of the solar system. (:19)
Duncan says it was Edmund Halley, of Halley’s comet fame, that figured this out in
the in the late1600s. But it took until the transit in 1761 for astronomers to prove
his theory was right.
CUT 3 “Edmund Halley figured out that if you could look at Venus moving in front of
the sun it would look different from two different vantage points. (:07) It’s like when
you are driving on any highway the trees and fences that are close to you seem to
move fast and the mountains that are further away seem to move slower. (:16) So if
you measure how fast something shifts, or how much it shifts from two different
places on the Earth, you can, if you’re clever with geometry, figure out how far away
they are. The first time we knew the size of our solar system was 1761 and 1769.”
(:32)
To observe the transit, Duncan says you need to get special dark, sun watching
glasses. He says do not under any circumstances look at the sun directly unless you
have these glasses.
CUT 4 “You have to be very careful if you look at the sun. The sun is so bright that
you can’t look at it without protecting your eyes with very, very dark glasses. Not
sun glasses but dark glasses. (:11) Sun watching glasses are a thousand times darker
than ordinary sunglasses. The company that makes them calls them the Eclipse
Shades. We call them eclipse-watching glasses.” (:26)
If you can’t get the dark glasses Duncan says you can still watch the transit by going
to the Fiske Planetarium web site at http://fiske.colorado.edu. He says they will post
a live image of the transit using a solar telescope at CU’s Bausch-Somers
Observatory. For most people in North America the transit will begin late afternoon.
-CUFiske Planetarium Website is at:
http://fiske.colorado.edu/