The Transits of Venus of 2004 and 2012

We are now on the eve of the second transit of a pair, after which there will be no other till the twenty-first century of our era has dawned upon the earth, and the June flowers are blooming in 2004. When the last transit season occurred the intellectual world was awakening from the slumber of ages, and that wondrous scientific activity which has led to our present advanced knowledge was just beginning. What will be the state of science when the next transit season arrives God only knows. Not even our children’s children will live to take part in the astronomy of that day. As for ourselves, we have to do with the present . . .
 
William A. Harkness, Proceedings of the 31st Meeting of the American Association for the Advancement of Science (1882)

Introduction

The 2004 Transit of Venus will the first occasion after 121½ years to observe a transit of the planet Venus across the Sun and it is expected that more people (both professional as amateur) will observe this unique astronomical event than ever before. The transit can be viewed completely from most of Europe, Asia and Africa and partially from most of the American continent. Observers who are located in regions where the transit is not visible or who are clouded-out by the weather will still be able to follow the transit on the Internet or on television (see the links on transit web sites).

Although the prime reasons for observing the transit in the past – the determination of the length of the astronomical unit – has now become obsolete with the introduction of laser-ranging techniques in the 1960s, the phenomenon remains spectacular and its rareness and associated history will hopefully inspire millions of people to observe this event.

Visibility Regions for the Transits of Venus of 2004 and 2012

The following diagrams depict the regions of visibility for the coming transits of Venus on 8 June 2004 and 5/6 June 2012.

Circumstances of the transit of Venus of 2004
 
Click on the image for a larger view Click on the image for a larger view
map legend   map legend  
 
Begin of the transit (8 June, 05:13 UT) End of the transit (8 June; 11:26 UT)
Sub-Venus point: λ = +101º 47'; φ = +22º 45' Sub-Venus point: λ = +8º 06'; φ = +22º 41'
Apparent diameter of the Sun = 31.51' Apparent diameter of the Sun = 31.51'
Apparent diameter of Venus = 0.96' Apparent diameter of Venus = 0.96'

This transit will take place just after Venus passes its descending node (7 June; 15:01 UT) and occurs on the southern half of the solar disk.

Observers located in or slightly north of longitude 60º N and latitude 125º W (Northwest Territories, Canada) will see the begin of the transit just before sunset and the end of the transit shortly after sunrise.

Circumstances of the transit of Venus of 2012
 
Click on the image for a larger view Click on the image for a larger view
map legend   map legend  
 
Begin of the transit (5 June, 22:10 UT) End of the transit (6 June; 04:49 UT)
Sub-Venus point: λ = –152º 39'; φ = +22º 52' Sub-Venus point: λ = +107º 09'; φ = +22º 47'
Apparent diameter of the Sun = 31.52' Apparent diameter of the Sun = 31.52'
Apparent diameter of Venus = 0.96' Apparent diameter of Venus = 0.96'

This transit will take place just before Venus passes its descending node (6 June; 16:50 UT) and occurs on the northern half of the solar disk.

Observers located in or near to Iceland will see the begin of the transit just before sunset and the end of the transit shortly after sunrise.

References


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