A rainbow can occur only when the sun is 40 degrees or less above the horizon.

The scarlet tanager, a songbird native to Illinois, can eat as many as 2,100 gypsy-moth caterpillars in one hour.

The reason why hair turns gray as we age is because the pigment cells in the hair follicle start to die, which is responsible for producing "melanin" which gives the hair colour.

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