PHYS 1600 Lecture Notes - Lecture 8: Friedrich Bessel, Cosmic Distance Ladder, Parsec
Document Summary
11- 1 distances to nearby stars are determined by stellar parallax. The closest star other than the sun, proxima centuari, in the constellation centuarus, is about 40 trillion km away. Light takes more than 4 years to get from here to there. The apparent motion of nearby stars among the background of more distant stars, due to earth"s motion around the sun is called stellar parallax. The word parsec (from parallax second) originated from the use of parallax to measure distance. Distance to a star in parsecs = __________________1___________ Where d is the distance to the star and p is the parallax angle of that star. Distance to a star in light years = Parallax angle of that star in arc seconds. Example: the nearest star, proxima centauri has a parallax angle of 0. 77 arcsec, and so its distance is. Equivalently proxima centuari is 4. 24 light years (ly) away.