towards the centre of the societies activities at our observatory at Kenley, Surrey, England. People who intend

to observe from other sites may find some of the information useful as well as the links to external web sites.

 

Local information for Kenley:

Local Circumstances for Greenwich – Kenley will be quite close
Ingress		*				Egress*
1st Contact Time UT: h m s	PA°	2nd Contact h m s	PA°	Mid-Transit h m s	PA°	3rd Contact h m s	PA°	4th Contact h m s	PA°
05 19 54	117.8	05 39 47	121.1	08 22 42	166.7	11 04 05	212.2	11 23 36	215.5
BST Times are 1 hour later than this i.e. 05:19:54 UTC is 06:19:54 BST
* NB. It is at 2nd & 3rd Contacts when Venus displays the "Black Drop" phenomena.

Table adapted from information on the SPA web site with Azimuth calculations by John Murrell

Prediction for Greenwich – Kenley will only be slightly different
Phase	1st Contact	Mid-Eclipse	4th Contact
	05 19 54		11 23 36
Altitude	12°	40°	61°
Azimuth	68°	103°	163°

Make sure that you have a clear horizon that covers the whole range of Azimuth a quick bit of surveying with a compass is advised (don’t forget to allow for the difference between magnetic north and true north ! )

 

Diagram showing the track of Venus across the Sun. Remember that your telescope / camera / projection arrangements may invert, reverse or invert and reverse the image. If you are using a high magnification check which way your image is round so that you can observe the correct area at first contact. You can check the orientation of your setup on the moon – even in daylight, just beware of viewing the Sun. You can use an up to date image of Sunspots on the Sun as a final check on viewing the correct quadrant. Daily Images of the Sun are available on SpaceWeather.Com, The SOHO web site and The Big Bear Solar Observatory.           Diagram Courtesy: Fred Espenak NASA

What to observe ?

The first observations of the Transit of Venus were made to measure the size of the solar system. This depended on accurate measurements from a number of places widely spaced across the surface of the Earth. While you can only take measurements in one place you can either team up with a friend overseas or join the European Southern Observatory programme that intend to collect measurements from a number of places across Europe and then analyse these to obtain a measurement for the size of the Solar System.

One major problem discovered by the observers was the ‘black drop’ effect where a dark band appears between Venus and the edge of the Sun just as Venus should be separating at second contact. This was first thought to be caused by the atmosphere of Venus but this was disproved when the same phenomena was observed during transits of Mercury which has no atmosphere. This was then believed to be contrast phenomena within the Human Eye / Brain however I have seen a report that the effect has been photographed. Take a number of photographs or a video of second & third contact and see if you can photograph these phenomenon. If you get time observe it by eye and describe what you see – a tape recorder may help.

Professional researchers are using the transit to allow them to analyse Venus’s atmosphere using space based telescopes such as TRACE. Analysis of previous measurements of Mercury have indicated that the phenomena is a combination of the Point Spread Function of the telescope and the limb darkening of the Sun – is this supported by your observations ?

Getting Ready for the Transit of Venus:

A copy of my presentation to the CAS meeting on Friday 16th April is here in PDF format {900kBytes}. Those who did not attend the meeting should note that this was only one of five presentations – I have not got copies of the others to put on this website.

Observing Tips:

Tips on how to observe the transit and some of the pitfalls are on a separate page located here.

If you have any tips please EMAIL them to ToV@Croydonastro.org.uk

External Links:

Fred Espenak, NASA - Brief History plus links to Predictions

University of Central Lancashire – Lots of Transit Information Here including details of the IAU meeting at Preston close to the place where Jeremiah Horrocks (1619 to 1641) made the first observations of a Transit of Venus On 24 November 1639 (Julian Calendar) in the tiny Lancashire village of Much Hoole,

Society for Popular Astronomy – Transit of Venus Page

BAA – Web page dedicated to the transit

BAA – Timing & other information on the transit (pdf)

European Southern Observatory – Pan-Europe education site & also compiling transit timings from amateurs

ESO ToV 2004 UK Node at University of Central Lancashire http://www.transit-of-venus.org.uk/vt-2004/

Transit of Venus – Educational Resource

Transit of Venus by Paper Plate Education !

Orpington AS Transit Site www.chocky.demon.co.uk/oas/venus.html

SPA/FAS/BAA Joint Site www.transitofvenus2004.org.uk

Sky & Telescope – Observing the sun & the Transit of Venus Page http://skyandtelescope.com/observing/objects/sun/

Includes a movie (1.2Mbytes) made from glass negatives of the 1882 Transit (as shown by Tony Sizer on 16^th April)  http://skyandtelescope.com/observing/objects/sun/graphics/Transit1882Todd640.mov

Chasing Venus – a web site from Smithsonian Institution Libraries – well worth a browse

BBC Transit of Venus a quick summary

James Cook and the Transit of Venus a NASA website describing James Cooks trip to Tahiti to view the transit

NASA Links for the Transit of Venus Look here for more links for both Historic & Observation Information

Open University  - Stardate web site – lots of information including a page to enter your timings and calculate the size of the Solar System !