Does the shadow of a bird shrink the higher it gets?
I feel extremely stupid for even asking this question but if a bird is flying close to the ground it’s shadow is the same size as the bird. If that bird were to be flying much higher would irs shadow then be smaller? Again I feel silly for even asking but I can’t find anything other than math problems online
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answers:
oldprof say: The shadow is the same size no matter how high the bird is flying...sort of.
Because the Sun is 93 million miles away, its rays are almost parallel when they reach the Earth. So no matter where that bird is in altitude its body will subtend the same area of sunlight and cast the same sized shadow.
Understand the rays are not absolutely parallel. There is the tiniest of divergence as they radiate out in all directions from the Sun. But we are unable to measure something that small.
But...a big BUT...without the most precise of measuring instruments, we cannot measure that divergence and the shadows cast by airborne objects like birds and airplanes will be the same size no matter what altitude they are at.
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Vaman say: No. It becomes bigger. You draw a cone with the size of the bird and the sun at the apex. This will give the answer.
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RealPro say: If the Sun was a point source, then the shadow would of course increase in size.
Since the light of the Sun comes from a disk instead of a single point, then there is no single word you can use to describe what happens, because there are different ways to define the "size" of a shadow.
The "totally dark" part (umbra) will become smaller (and eventually disappear) when the bird goes higher, while the "total" (penumbra) will increase.
The same way they do when you move your hand in front of a flashlight.
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Morningfox say: Yes, the shadow shrinks. But the full discussion of this gets into things called "umbra" and "penumbra" and even "antumbra", the different parts of a shadow.
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frank lynn say: Due to the Brobdingnagian size of the sun, the bird's shadow disappears as it increases its distance from the ground. The sun is not a point source so the bird's shadow neither grows nor shrinks as the bird gets farther away from the ground.
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david say: The shadow cast upon the ground does get smaller. It is a matter of geometry. At some point, the bird can be high enough that it will not have a shadow.
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Captain Matticus, LandPiratesInc say: It more or less stays the same size, because the rays of light coming from the sun are pretty much striking the earth in parallel lines (they're not truly parallel, but they're close enough, given that the earth is very small and is very far away from the sun).
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