AS102 Study Guide - Final Guide: European Space Agency, Parsec, Hipparcos
Document Summary
Your textbook describes the term parallax quite well and there is no need for me to repeat it here. The term stellar parallax refers to the little angle p in fig. 6. 2 (shown below) which means that half the baseline of the main triangle in this figure is 1 au, another convenient solar system distance unit. It turns out that distances measured in this way to even the nearest stars are large numbers in kilometers or even aus so astronomers have developed two other measurement units to make life simpler. One of these, light-year, is the main measuring unit for this textbook. A light-year is simply the distance light travels in one year. The other, parsec, is sometimes used by astronomers and its definition can be found in your textbook. The earth"s atmosphere causes a blurring of stellar images so this limits our use of this technique to stars that are closer than about.
