The speed of light.

Recently, we have waded a little out to sea, enough to dampen our toes or, at most, wet our ankles. The water seems inviting. The ocean calls. Some part of our being knows this is from where we came. We long to return. These aspirations are not,I think, irreverent, although they may trouble whatever gods may be.The dimensions of the Cosmos are so large that using familiar units of distance,such as meters or miles, chosen for their utility on Earth, would make little sense. Instead,we measure distance with the speed of light. In one second a beam of light travels 186,000 miles, nearly 300,000 kilometers or seven times around the Earth. In eight minutes it will travel from the Sun to the Earth. We can say the Sun is eight light-minutes away.