Preparing for the Transit of Venus

There will be a transit of Venus on June 6th.

Transits of Venus occur when the sun, Venus and the Earth are in the same plane, with Venus between the Earth and sun so that the planet Venus appears moving across the disk of the sun.

This is among the rarest of planetary alignments.

Only six such tranists have occurred since the invention of the telescope (1631, 1639, 1761, 1769, 1874 and 1882).

Two transits of Venus occur in my lifetime - June 8, 2004, and the other (as yet to occur), will be on June 6, 2012.

If you think it is a strange coincidence that these two transits both happen in June, it might interest you to know that these transits only occur in early June or early December.  There is more to this pattern than the months.  They always occur in pairs separated by 8 years.  In fact, the transit pattern of recurrence are at intervals of 8 years, 121.5 years, 8 years and 105.5 years.  The next pair of Venus transits will be December 11, 2117 and December 8, 2125. 

The planet Mercury can also transit the Sun, but does so more frequently since Mercury orbits the Sun more quickly than does Venus.  There are about 13 or 14 transits of Mercury every century. All Mercury transits occur in either May or November.

Transits are like four-act plays, with each "act" referred to as a contact. 

Contact I is the instant when the planet's disk begins to cross the Sun's disk.

Contact II is when the complete planetary disk is visible against the Sun's disk.

Contact III is when the planet has moved across the Sun's disk and the planet's disk once again touches the edge of the Sun's limb.

Contact IV is when the planet's disk has completely moved beyond the Sun's limb.

Today I had my second "dry run" for the transit.

My current plan is to observe the transit in my backyard.

I will have a Questar for direct viewing, a Coronado PST for viewing in H-Alpha light, and a Solarscope.

I have only just recently ordered the Solarscope, but have not yet received it.  My wife is an elementary school teacher, and every year we have a Sun Day at her school.  I teach the children about aspects of safety and dangers of observing the Sun, and let them look through the telescopes.  The Solarscope will be a good addition to these events.

I am also planning to build a projection device for my 10 inch reflector.

I'm working on several designs.


I will be using a digital eyepiece that will be hooked up to a VCR and an old analog television set.

Of course, I'll be connected to the Internet to view the event through different telescopes throughout the world.