If you don't know how far something is, you can estimate its distance by multiplying the object's size by ten. So, if you want to know how far the moon is away, multiply the diameter of the moon (3,476 miles) by 10. Then divide the answer by the time it takes light to travel the same distance. In other words: 3,476 x 10 = 34,760. Divide that number by .0005 seconds, which equals 740,000. Now you know that the moon is about 740,000 feet away.