When dealing with astronomical quantities such as distance, the numbers involved are indeed truly astronomical. Or in some cases, infinitesimally small. So, we need appropriate notation in dealing with them. The first simplification is to use powers of 10 notation, so that we write 6,000,000 as 6 × 106, and 6/1,000,000 as 6 × 10−6 = 0.000006. But of course, we need units to go with these quantities and both the large and small quantities come from the nature of light and other electromagnetic radiation. In some instances, if there are not too many zeros to contend with, the number itself can be written without the powers of 10 notation. Scientific measurements are invariably done in the metric system which is very amenable to scientific notation as will become evident.