The Venus Transit 2004
... Photos by Themes
The "Black Drop" Phenomenon
On this page, photos related to the so-called "Black Drop" phenomenon are displayed, as they were recorded during the Venus transit on June 8, 2004 and shown at the VT-2004 website. This effect is illustrated on the drawing to the left and has been known by observers since long. It implies that Venus appears to be "stuck" to the limb of the Sun near the moments of the second and third contacts, as if with some kind of chewing-gum. It makes it difficult to estimate the moment when the border of Venus' dark circle exactly touches the border of the Sun.
Details about this phenomenon were placed on a dedicated webpage, warning all observers to be careful when timing the contacts. However, the experience during this year's transit proved that it must have been mostly due to the lesser optical quality of the telescopes that were used to observe the transits in the XVIII and XIXth centuries.
In any case, as the photos on this page demonstrate, the "Black Drop" phenomenon obviously did not play any significant role this time. Many observers remarked that they did not suffer any particular difficulties with the timing and many image sequences (see below) testify to the general absence of such an effect. Look also at the special page in the VT-2004 Photo Archive that deals with image processing techniques on photos obtained near the moments of the contacts.
An overview of the VT-2004 Photo Archive is available and a number of these photos have been elected "VT 2004 Photo of the Day" .
All photos on this page may be downloaded and used, provided the photographers (authors) and the VT-2004 programme are indicated as source.
Individual Photos Displaying the Varying Degrees of the "Black Drop" Effect | |
| Venus Transit - 2nd Contact [640 x 480 pix - 92 | Venus Transit - 2nd Contact [2900 x 1946 pix - 161k] |
| Venus Transit - Second Contact [384 x 288 pix - 47k] | Venus Transit (Black Drop) [604 x 564 pix - 25k] |
| Near 2nd Contact [800 x 640 pix - 38k] | Venus Transit - Third Contact [384 x 288 pix - 50k] |
| Venus at 3rd Contact (3) [320 x 240 pix - 42k] | Near Third Contact [640 x 480 pix - 16k] |
| Third Contact [800 x 640 pix - 18k] | |
Photo Sequences Near Second Contact | |
| Venus Transit - The Beginning [512 x 1024 pix - 22k] | Venus Transit (Ingress) [1300 x 975 pix - 110k] |
| Venus Transit (Composite) [900 x 823 pix - 197k] | |
Photo Sequences Near Third Contact | |
| The Black Drop and Optical Resolution [406 x 606 pix - 77k] | Third Contact at High Resolution [1500 x 554 pix - 73k] |
| Black Drop Development [408 x 1006 pix - 173k] | Venus Exit [1200 x 960 - 106k] |
| Black Drop Effect [503 x 1300 pix - 41k] | Venus Transit (Egress) [1300 x 975 pix - 100k] |
| Venus Transit (Composite) [900 x 823 pix - 197k] | Venus Transit - Near Third Contact [1424 x 493 pix - 117k] |
| Venus Transit (Egress) [320 x 240 pix Animated GIF - 383k] | Venus Transit - Black Drop Phenomenon [350 x 237 - 22k] |
| Venus Transit - Egress [1280 x 1200 pix - 175k] | |
