PHYS 190 Chapter Notes - Chapter 6: Apparent Magnitude, Inverse-Square Law, Energy Star
13 Feb 2018
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Document Summary
Distance - most important & most difficult measurement in astronomy, & astronomers have many diff ways to find distances to stars. Each way depends on simple & direct geometrical method much like method surveyors use to measure distance across river they cannot cross. To measure distance across river, team of surveyors begins by driving 2 stakes into ground. Surveyors choose landmark on opposite side of river, establishing large triangle marked by 2 stakes & tree. Using instruments, surveyors sight tree from 2 ends of baseline & measure 2 angles on their side of river. Astronomers use very long baseline, size of earth"s orbit. Baseline - distance b/w eyes, parallax - angle through which thumb appears to move when switching eyes. The further away the thumb, smaller the parallax. B/c stars are so distant, parallaxes - very small angles, usually expressed in arc seconds.
