ASTR 1103 Lecture Notes - Lecture 4: Parsec, Hipparcos, Lagrangian Point
9 Feb 2020
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Document Summary
Lecture 4: the apparent shift in the position of a foreground object due to a change in the location of the observer"s viewpoint. Stellar parallax (p: defined as half of the total angular shift of a star during half the year. The astronomer"s triangulation method: stellar parallax the small apparent shift in position of a nearby star relative to distant background stars due to earth"s orbital motion, stellar distances are regularly expressed in light years and parsecs. The parsec: the distance to a star that has a parallax of one arcsecond, 1 parsec = 3. 26 light years. 1 arcsecond parallax: 1/360 = 1 degree, divide that 1 degree by 60, 1/60 = 1 arcminute, divide that 1 arcminute by 60, 1/60 = 1 arcsecond, one dime 2 miles away covers the angle of 1 arcsecond. In other words, it"s a very small angle, but over the span of the universe it adds up to a great distance.
