Observation by Pete Lawrence: Venusian Green Flash

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Observer

Pete Lawrence

Observed

2019 Oct 16 - 17:15

Uploaded

2019 Oct 18 - 18:23

Objects

Venus

Equipment
  • Canon 6D DSLR, Sigma 50 - 500 telephoto lens set at 500mm focal length
Exposure

1/64s exposure @ ISO 2000 with the lens aperture set at f/8

Location

Leicester, UK

Target name

Venus

Title

Venusian Green Flash

About this image

Pete reports that, following a beautifully clear day he attempted to get an early view of Venus low above the south west horizon after sunset. Although the planet wasn’t visible to the naked eye on this occasion it was an easy binocular target. It also stood out fairly well in a number of photographs he had taken as the planet approached the horizon. Having photographed the sunset earlier, he noted that there was plenty of green visible along the northern edge of the Sun, an effect caused by atmospheric dispersion. The thought occurred as to whether it would be possible to capture the atmospheric dispersion of Venus at this time as well. The effect was present as Venus got lower but was small and heavily affected by atmospheric seeing. The best way to catch it would be to use video, but as Venus headed for the horizon, the equipment was set up for stills and so he decided to try his luck. The appearance in this image lasted for a fraction of a second, "seeing" having destroyed the effect both before and after this shot. It shows an almost perfect dispersion of the light of Venus through Earth’s atmosphere with red at the bottom and green at the top. The blue component, which should be there has been scattered away. The pylons in this shot are roughly 1.3 miles away, the tree line 1 mile. The horizon is virtually perfect in that it is around zero degrees altitude. Being able to capture this fleeting glimpse of an atmospheric phenomenon is very special.

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