According to Wikipedia: A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun. The duration of such transits is usually measured in hours (the transit of 2004 lasted six hours). A transit is similar to a solar eclipse by the Moon. While the diameter of Venus is almost 3 1/2 times that of the Moon, Venus appears smaller, and travels more slowly across the face of the Sun, because it is much farther away from Earth.
This image, from The Star, shows Venus transits across the sun as seen over Hong Kong on June 8, 2004 (Image: Reuters)
Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The transit of Venus on 5 and 6 June 2012 will be the last Venus transit this century; the prior transit took place on 8 June 2004. The previous pair of transits were in December 1874 and December 1882. After 2012, the next transits of Venus will be in December 2117 and December 2125.
The entire transit will be visible from the western Pacific Ocean, northwesternmost North America, northeastern Asia, Japan, the Philippines, eastern Australia, New Zealand, and high Arctic locations including northernmost Scandinavia, Iceland and Greenland. In North America, the Caribbean, and northwestern South America, the beginning of the transit will be visible on 5 June until sunset. From sunrise on 6 June, the end of the transit will be visible from South Asia, the Middle East, east Africa and most of Europe. It will not be visible from most of South America or western Africa.
Where the 2012 transit will be visible
Transit start and end times (in UTC) are available for various international cities and various US cities.
Viewed from Malaysia, the planet will cross the Sun around 6.09am on June 6 (Wednesday), but it can only be seen after sunrise and will end at about 12.50pm.
People in Sabah will be able to see the entire phenomena because the Sun rises before the transit begins.
If you are in the Klang Valley or nearby and would like to have a better view of the Venus transit, drop by at the National Planetarium between 8am to 1pm where the National Space Agency (Angkasa) will be setting up a number of telescopes.
Alternatively, you can watch the transit from 8am to 12.50am via http://www.angkasa.gov.my/planetarium or view the live photos taken from Sandakan through Malaysia Lunar Eclipse Facebook from 6.10am to 12.40am.
If you miss it this round, the next Venus transit is predicted to be on Dec 11, 2117.
Safety precaution: A transit of Venus can be safely observed by taking the same precautions used to observe the partial phases of a solar eclipse. Staring at the Sun without appropriate eye protection can quickly cause serious and often permanent eye damage.
The safest way to watch a transit is to observe an image of the Sun projected onto a screen through a telescope, binoculars, pinhole or reflected pinhole. The event can be viewed without magnification using filters specifically designed for this purpose, such as an astronomical solar filter or eclipse viewing glasses coated with a vacuum-deposited layer of chromium. However, the disk of Venus is tiny compared to the sun and not much will be seen. The once-recommended method of using exposed black-and-white film as a filter is not now considered safe, as small imperfections or gaps in the film may permit harmful UV rays to pass through. Observing the Sun directly without appropriate protection can damage or destroy retinal cells, causing temporary or permanent blindness. (Wikipedia)
- Venus transit as seen in Kuala Lumpur
A video from NASA
- More images from NASA
- The Star.. Last chance to see rare Venus Transit