THE APRIL 9TH 2017 FILMING
Proof that the sun does not (and cannot) shine through the tunnel.
Normally the chances of an unobstructed sunrise in early April are pretty slim, but in 2017 Brunel's birthday occurred in an unusual run of fine weather, and coincided with train services through the tunnel being suspended for maintenance.
The BBC took this unique opportunity to film the April 9th sunrise from both ends of the tunnel, presented by engineer Roma Agrawal. The results confirm that though the tunnel is aligned towards the general position of the sunrise, from the far western end no light shines through the tunnel – it only reaches a small way in.
Video and stills taken from the eastern portal correspond to my predicted position shown in my calculated alignment (which shows it actually aligns on April 7th; April 9th is off the top of the chart) and predicted view -
The question remains as to whether the sky can actually be seen through the tunnel.
The BBC did not use an extreme telephoto lens to film through the tunnel, so the only views of the eastern portal from the western are disappointingly small, consequently when enlarged they are at the limits of definition and overexposed. However they are an improvement on my 1976 photograph, and have the advantage they are in colour
Eastern portal from western in daylight
Enlarged and the exposure adjusted. There is green to the crown of the tunnel -
As the sun is rising. It does not show the intense light a direct view of the sun would, with the sides and roof of the tunnel illuminated by the light shining directly down it -
Video courtesy of the BBC One Show 30th May 2017
Video courtesy of the BBC One Show 30th May 2017
Enlarged view
Image courtesy of the BBC One Show 30th May 2017
Image courtesy of the BBC One Show 30th May 2017
Image courtesy of the BBC One Show 30th May 2017
Eastern portal from western at dawn
The rising sun