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Observing the transit of Venus 2012

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Observing the transit of Venus 2012

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The planet Venus put on a spectacular show on Wednesday morning as it passed in front of the face of the Sun.
 
The Transit of Venus is an extremely rare event which occurs only twice every century. This will not occur again before the year 2117. In Malta this event was visible between sunrise at 5:45 a.m. and 6:55 a.m.
 
The weather conditions were favourable overall with the Sun being visible for most of the time.
 
However at times, as the Sun heated the sea surface, it produced clouds by convection, some of which covered the Sun for part of the time.
 

A moderate force four wind from the WNW did create some turbulence, making it a bit difficult to take very clear photos. The temperature, at 18 degrees celcius, and a humidity of 78 percent did not affect the photo quality and air turbulence.
 
Stargazers were able to spot Venus passing over the Sun’s disk with the magnification of a camera (using an appropriate Sun Filter) as a very tiny black dot on the Sun’s disk. Using telescope magnification, Venus was visible as a small dot slowly transiting the Sun’s surface.


sun transit

 
Amazingly, only six of all of these transits have been observed by humans (in 1639, 1761, 1769, 1874, 1882 and 2004). The next will take place during December 2117. Scientifically, these transits are of great importance and value as they can be used to learn more about a planet’s atmosphere, solar system size and distance between celestial bodies.
 
During a transit Venus makes five ‘contacts’; first contact (when Venus is still outside the Sun’s disk and moving inwards), second contact (when Venus is completely inside the Sun’s disk and is touching the edge of the disk and is moving inwards), greatest transit (when Venus is at the middle of its trajectory across the Sun’s disk), third contact (when Venus is completely inside the Sun’s disk and is touching the edge of the disk and is moving outwards) and finally fourth contact (when Venus is completely outside the Sun’s disk and moving outwards).


sun transit

 
In Malta, only the part of the trajectory - third and fourth contacts were visible. During third contact the transit exhibited another amazing phenomenon; that of the Black Drop Effect. This is an optical illusion, which occurs when light is bent around Venus due to turbulence in the atmosphere, causing it to look stretched, obtaining a tear-drop like shape.
 
The photos were taken by Andrea Muscat during an observation at Xwejni near Marsalforn in Gozo.
 
Equipment used included, Galileo Telescope, Sun Filter and Astronomy Webcam.