BLUEMOMENT

With general cloud cover pierced by shafts of sunlight why is it that the shafts fan out as though originating from a source much closer than 93 million miles away?

JUst wait, DAve, if your really lucky at some point this year the general cloud cover may have two holes and you can witness a solar interference pattern

Silkie wrote:With general cloud cover pierced by shafts of sunlight why is it that the shafts fan out as though originating from a source much closer than 93 million miles away?

That's because Uranus is brown
C_W

Is it not some thing to do with photons and Klingons?

Refraction?
Like waves bend round a breakwater or headland

Silkie wrote:With general cloud cover pierced by shafts of sunlight why is it that the shafts fan out as though originating from a source much closer than 93 million miles away?

The clouds are generally a long way away (3000 - 5000' vertically plus any horizontal distance) so the hole in them is bigger than you might think. The sun being a long way away the beam of light is more or less parallel sided, but is it goes from "far away" to "quite near" it seems to get bigger. See also: perspective, renaissance rediscovery of.

Or it could just be that the sun is on a crystal sphere about ten miles up.

Purely an effect of the viewer's perspective then?

Silkie wrote:Purely an effect of the viewer's perspective then?

I've only just managed to sign into bluemoment again after over a year and a half in the wilderness - the bot filter has a mean and intransigent manner! - so this is a bit of a test post too...

I took a copy of your photo, opened it in "paint" and drew straight lines parallel to the rays on it.

I found that the lines converge on a point one third up from the bottom and one third in from the right of the square "block" of cloud where, presumably, you would find the sun if the cloud moved.

Actually it worked quite well for me - no noticable optical distortion on the photo - but I couldn't quite bring myself to the effort of photobucketing the results, sorry.

The rays radiate (now there's a surprise) from the sun which is a point source as you can see from the picture. The fact that you can see them fanning out is due to the relative positions of the sun, clouds & observer. They are not all in line are they?

Arghiro wrote:The rays radiate (now there's a surprise) from the sun which is a point source as you can see from the picture. The fact that you can see them fanning out is due to the relative positions of the sun, clouds & observer. They are not all in line are they?

It took me a minute or two to figure out whether your question was aimed at me and even then only when I interpreted "in line" to mean converging. - I could still be wrong in this - if so - my apologies!

Yes - they are all converging to a point source that can be inferred behind the cloud - do the exercise for yourself.

There is a minor "cocked hat" which depends on how close to parallel with the rays you can set your straight lines and at best can radiate from any point within the suns "disc" (not quite a point source).

Just don't fly too close or the wax in your wings will melt and the feathers will come loose.

Generally speaking, it's 8 light minutes away, normally far enough for the likes of us.

Silkie wrote:Purely an effect of the viewer's perspective then?

Yup. In that case the aperture is a long transverse slot between rows of cloud, so you're looking at an inclined triangular sheet of light.