Transcript: Astronomy contains an enormous range of scales and length as well. The smallest thing that we can routinely measure is a proton; the diameter is 10-15 meters. The size of a hydrogen atom is 10-10 meters. Somewhere in the middle of the huge range are human beings at about 1 meter in round numbers. The next largest scale we might consider is the size of the solar system or the Earth-Sun distance, 1 Astronomical Units, 1011 meters. A lightyear, a typical distance to a nearby star, is five orders of magnitude larger, 1016 meters. The milky way, the system of stars in which we live, is 1021 meters across. And the observable universe containing billions of galaxies is 1026 meters. The full range of scales from the largest to the smallest is 41 orders of magnitude or powers of 10.