Venus Occultation - 18 June 2007
The occultation of Venus by the Moon viewed from the top of Jebel Hafeet (24°03'29.7"N 055°46'35.6"E 1051m)

 

Photos and text by Bob Reimer

While the disappearance of Venus behind the Moon is not a tremendously rare event (it happens several times a year), it is unusual that it occurs at a place and time that is convenient for a particular observer.  On June 18th, 2007, it was ideally placed for observers in the Middle East.  We could view the event in the early evening. 

Occultation is the general term used for one object hiding another.  When the objects are roughly the same apparent size, we call them eclipses (lunar and solar eclipses), while if the object hiding the other is apparently much smaller, we call them transits (transit of Venus in front of the Sun).  Occultations are an important tool for astronomers as they can give us information about both the object being hidden and the object doing the hiding.  Parts of the surface of the moon and asteroids have been mapped by observing the shadows thrown on the earth by the star or planet they are hiding.  The rings of Uranus were discovered because stars were disappearing at unexpected times during an occultation event.  Many double stars have been discovered this way as observers have noted that stars did not disappear instantaneously as they should. The International Occultation Timing Association's flyer about occultation observing provides more detail on the rational for observing occultations and the history of what the methodology has discovered while their 384 page manual provides a more detailed history and goes into excruciating, but sometimes fascinating, detail about how to observe an occultation event.

A small contingent of ENHG members met at the zoo with a few more joining at Jebel Hafeet.  We were armed with binoculars, a spotting scope supplied by Brigitte Howarth and a 500mm lens with 1.4X teleconverter on a 10mp digital SLR.  As we left we were worried about the amount of cloud in the sky, but as the sun set, the Moon and Venus shone through the high overcast as illustrated in the first frame below.  As we watched, 20-30 passersby enjoyed views through the camera and the spotting scope.  The spotting scope gave an excellent clear view of the Moon and Venus because it was less affected by the wind due to its smaller size.  The disappearance of Venus took us by surprise.  The camera had been set to go off on timer near the event, but I hadn't realized the timer would pause if other pictures were taken.  When Brien called out that it was disappearing, I watched Venus fade behind the Moon without thinking to manually click the shutter :(  When the time for the reappearance arrived, we were better prepared and the camera was taking an image every two seconds. 

Those of us who were able observe the event enjoyed it very much.  Those that happened on us serendipitously were very appreciative of the opportunity to view the Moon and Venus through our equipment.  I hope the pictures below will give you some sense of what it was like.