PHYS 3510 Lecture Notes - Lecture 2: Observable Universe, Parsec
Document Summary
The universal context of life (chapter 3) The quiz 2 deadline will be next wednesday (jan 20) We will cover chapter 3 this week. The big bang and the expansion of the universe. In this course, we will encounter distances which are much larger than we are used to in everyday life. Familiar units of measurement (e. g. , km) will be awkward to use. We will therefore introduce two new units of distance measurement. The astronomical unit (au) is defined as the average distance between the earth and the sun. 1 au = 150 million km (1. 5 x 108 km) Au are very useful for describing distances within our solar system. The sun is 150 million km away. While an au may seem huge, it is not very useful for describing distances beyond the solar system. Even the nearest star (proxima centauri) is 270,000 au away! We therefore introduce a larger distance unit called the.
