Question

When a bird flies in the sky, why does not its shadow fall on the ground?

Answer 1

Birds can and will cast shadows when close to the ground. They need to be far closer, but they still can cast shadows. But to make proper shadows, the object needs to have an angular size close to or larger than that of the sun- it needs to block out the sun. But pbirds are usually high enough to not cast a major shadow - they appear too small.