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PostPosted: Sun Dec 08, 2019 6:36 pm 

Joined: Sun May 11, 2008 6:11 pm
Posts: 3303
Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
8th December 2019; 1450 UT; Windy and cloudy in the afternoon but a rather limited gap in the cloud-cover revealed a surprising but very quick view of VENUS in daylight, using L/S 60mm spotter from the garden...but was very soon clouded-out. [obs.#584] -------leading to very heavy cloud, part of which broke to reveal the Sun fairly low down and a torrential shower produced superb, spectacularly coloured rainbow--- both primary and secondary bows seen and photographed. regards maf.

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PostPosted: Sun Dec 08, 2019 9:44 pm 

Joined: Fri Dec 10, 2004 10:34 pm
Posts: 369
Location: Surrey
One interesting thing to do with a rainbow is to image it / view it through a polarising filter. At certain angles the rainbow dissapears completely showing the light is polarised. I am nor sure if the polarisation is the same all round the arc as the images I have where I experimented with a polarising filter show only part of the arc and then show it missing with the filter rotated.

At the time I was a bit confused about what my polarising filter does as it is a circularly polarised filter designed for digital cameras. I thought that it only let left or right handed circular polarised light through but I have since realised that assumption is an error. These filters consist of a linear polariser (on the outside) followed by a circular polariser nearest the lens. They are made like this as linear polarised light confuses the sensor on the camera. They are quite interesting as they are directional - you get a different effect if you look through them the other way.

Engineer @ Work - Astronomer @ Play

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