Today's interesting fact has to do with Polar Bears.

Many people think polar bears are white, but they are not.

The polar bear's skin is black, from the tip of the nose to the tip of the tail.

While the fur looks white, it is actually transparent when viewed in a microscope, we see it as white due to limited diffraction and reflection of light.

If you look carefully at a hair, you will notice that it not just clear but it is also hollow.

The hollow core serves several purposes.

First it provides buoyancy when swimming.

Second the air in the hollow provides additional insulation.

Third like the most modern optical fibre which are now hollow, this core helps channel light down to the skin of the bear, where the black skin absorbs any residual heat.

This fur, combined with the layer of fat beneath the skin, allows polar bears to function in temperatures less than 70 degrees Centigrade.