There is an interesting phenomenon of the Venus Transit which is known as The Black-Drop Effect. The Black-Drop Effect occurs when the edge of the Venusian disk appears to deform and cling to the limb of the Sun. The "black drop" is an optical illusion which is the result of seeing problems due to the Earth's turbulent atmosphere.
There are several stages in the 6-hour-long Venus Transit experience and The Black-Drop can potentially occur during two of them. They are as follows:
FIRST CONTACT - (not necessarily of the Third kind:) This is when the silhouette of Venus just starts to creep onto the disk of the Sun.
SECOND CONTACT - the silhouette of Venus just breaks away from the edge of the Sun and is seen completely against the bright photosphere. Here is the potential "Black Drop" effect, when a piece of Venus appears to remain attached to the blackness beyond the edge of the Sun.
MIDTRANSIT - occurs about 3 hours into the Transit
THIRD CONTACT - when Venus makes contact with the far edge of the Sun. (The Black-Drop Effect can occur here also)
FOURTH CONTACT - when Venus finally leaves the face of the Sun
Guy Ottewell, in his 'Astronomical Calendar 2012', walks us through the Venus Transit's phases, instructing us on the potential for the Black-Drop Effect:
"The moment of First Contact is difficult to judge: the planet, as yet an invisible part of the sky, has to dent the Sun's limb, and this can hardly be noticed until some seconds after it has happened. Instead, wait through the 18 minutes during which the (tiny venusian) black spot slowly enters the blazing wide (solar) disk.
There comes a stage when you think the planet is all inside, tangent to the edge. But wait some long, suspenseful seconds more! The black spot becomes slightly stretched toward the limb; then seems to hang by a short thick stalk from the great black curve like a 'black drop'. This deformation is apparently caused by irradiation (spreading of brighter light in the eye) but may also be affected by turbulence in our atmosphere, since it is more marked when the limb of the Sun 'boils.' Suddenly the thread breaks: Venus is completely if infinitesimally surrounded by light. The instant of the breaking is Second Contact.
Similarly, just over 6 hours later, at Third Contact: the planet squeezes to a slightly oval shape, reaches out to touch the Sun's limb, suddenly becomes stuck to it by a thread - press your stopwatch at that instant: Third Contact." i.e. Contact of the Third Kind.
FUSION is the underlying concept of The Black-Drop. It is the meeting at the center of a bridge:
When Venus is near the limb of the sun - the critical moment for transit timing - the black of space beyond the Sun's limb seems to reach in and touch the planet. You can recreate the black drop effect with your thumb and index finger: Hold the two in front of one eye and narrow the distance between them. Just before they touch, a shadowy bridge will spring across the gap. According to John Westfall, writing for Sky & Telescope magazine in June 2004, "this is simply the result of how two fuzzy bright-to-dark gradients add together."
Two disparate energies reach out for each other and Fuse into a connective bridge between two realities. Listen to Alan Oken describing the energy of both Venus and Gemini as being one of FUSION:
"Venus represents the energy of FUSION. Let us see this from the relationship Venus has to Gemini. ... It is on the level of the soul that the duality of Gemini ceases. What remains is exemplified in the Tarot card for this position (Venus in Gemini). This is "The Lovers" card and indicates through the joining of the male and the female, the union of the two opposites yielding ultimate fusion and oneness. It is here the relationship between the soul and the personality becomes established. As a result, the soul can communicate with its "shadow" (the personality) and the shadow "in deep meditation" contacts the source of its light, the soul. The eventual marriage between the soul and the personality is now on its way towards completion." - Alan Oken
The Black-Drop effect hints at something profound and mystical and can help us to understand the sweet message of the Venus Transit in Gemini. Venus kisses the Sun.
Photos of the Black Drop Effect at Second & Third Contact
http://www.eso.org/public/outreach/eduoff/vt-2004/photos/vt-photos-top05.html
Info on the Black Drop Effect
http://www.transitofvenus.org/history/black-drop
