Transit of Venus across the Disk of the Sun

No person alive today has seen the Transit of Venus across the disk of the sun that last occurred on 6th of  December 1882.   There have been only 5 previous transit observed by humans the first in 1639, 1761, 1769, 1874,  and 1882.   If it is clear we will observe it from sunrise around 5:43AM until it ends around 7:26AM in the morning from the roof of  the Parking Garage at Fenton and King Street on Tuesday, June 8, 2004.  If  it is hopelessly cloudy and predicted to continue that way well past the event then we will have a show in the planetarium watching web cams of this event.   The real thing is better!
The reason why transits of Venus across the disk of the sun are important, aside from the spectacle and their rarity, is that is how we know that we are 8.3 light minutes (149 million kilometers, 93 million miles) away from the sun.  By measuring the distance on the earth between two observers and the small angular difference between the two observers transit of  Venus; we can scale up the earth distance to give us the earth to Venus distance and from that the earth to the sun distance of 1 AU (Astronomical Unit).  All other distances to planets, stars, and galaxies are based upon this first close distance in our Solar System the AU.  Before the AU was determined in terms of some known value on the earth we could not say how far the planets or stars or galaxies were away.   All distances off of the earth are based upon our determination of the AU,  and this is only our 6 opportunity to use this method with the transit of Venus across the disk of the Sun.  Come join us for this scientifically historical event.  The next transit of Venus occurs in 8 years in 2012, but then it will be visible from here near sun set, and you can not afford to wait until 2117.   Snoozers on this earlier morning event will be losers.

Montgomery College's Planetarium home page

Last updated 9:20PM  6/21/2004 by Dr. Harold Williams