Science Questions

Why do sunbeams appear to spread out?

Mon, 24th Oct 2011

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Question

Kenneth Silva asked:

Distance of sun from Earth.

 

I was out, walking my dog this morning, just as the sun came up. There was a thin cloud cover, but the sun's rays were coming through. I noticed that the light rays came in a fanned pattern. If I trace the rays back to a point of origination, I determine that the sun is maybe a mile up in the sky.

 

Either they've been lying to us all these years as to how far away the sun is, or something else is going on here.

 

Why are the light rays fanned out? Shouldn't they be more parallel if the sun is 93,000,000 miles away?

 

Thanks.

Ken Silva

Phoenix, AZ

USA

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Kenneth Silva asked the Naked Scientists: Distance of sun from Earth. I was out, walking my dog this morning, just as the sun came up. There was a thin cloud cover, but the sun's rays were coming through. I noticed that the light rays came in a fanned pattern. If I trace the rays back to a point of origination, I determine that the sun is maybe a mile up in the sky. Either they've been lying to us all these years as to how far away the sun is, or something else is going on here. Why are the light rays fanned out? Shouldn't they be more parallel if the sun is 93,000,000 miles away? Thanks. Ken Silva Phoenix, AZ USA What do you think? Kenneth Silva , Sat, 15th Oct 2011

It is a perspective effect the rays are straight parallel lines but they appear to converge in the same way that railway tracks appear to converge as they recede into the distance. Soul Surfer, Sat, 15th Oct 2011

I think the light has to be coming from a nearby bright spot caused by different densities in the cloud to observe that effect. The "rays" look as if they are emanating from the sun, but they are really emanating from an image of the sun projected onto something in the Earth's atmosphere. Geezer, Sat, 15th Oct 2011

Is this what you mean?
http://en.wikipedia.org/wiki/Crepuscular_rays Bored chemist, Sat, 15th Oct 2011

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