2 replies to this topic

[tedbnh]

I was in Florida visiting my new granddaughter :-) for the passage of Venus near the Pleiades last week. I was checking Stellarium to see how close Venus would come and just for fun decided to see whether it would look any different from home back in New Hampshire.

I was amazed at the amount Venus shifted position against the stars of the Pleiades when I clicked back and forth on the location map between NH and FL.

To do this demo, set your Stellarium date and time to April 3, 2012 at 21:15, and do a 'find' on Alcyone. This will center the field on the bright star in the Pleiades.

Now bring up the location map, drag it down so it does not interfere with the image of the cluster, and click back and forth between say New England and Florida. (You have to choose a time and place where it is dark in both spots, unless you tell Stellarium not to show the daylight anywhere.)

[Pharquart]

It's the same parallax that made the transits of Venus back in the 1800's so important, wasn't it? The timing of initial contact (and the transit duration) are different depending on where you are on the globe. Expeditions were sent around the globe in 1874 to watch. Using data gathered from these timings, astronomers could then calculate the distance to the sun.

Brian

[tedbnh]

Absolutely correct! I was thinking more of a basic astronomy demo of how we use parallax to find actual distances to nearby stars, but you are right about the special use of the Venus transit. In fact this year there is an iPhone and Android app available to participate in a modern calculation of this experiment. See www.transitofvenus.org to get the app and participate in the calculation live.

It's the same parallax that made the transits of Venus back in the 1800's so important, wasn't it? The timing of initial contact (and the transit duration) are different depending on where you are on the globe. Expeditions were sent around the globe in 1874 to watch. Using data gathered from these timings, astronomers could then calculate the distance to the sun.

Brian