AS101 Lecture Notes - Lecture 2: Spiral Galaxy, Observable Universe, Googol
Document Summary
In general, a model is something that represents reality. A scientific model is an idea that can be used to describe an aspect of reality and has withstood observational or experimental tests. We can also develop conceptual models to help us think about how nature works. How do we setup a scale model: scale = actual size/desired scale size. To resize the sun so it fits in this room, the scale would be a factor of about 80,000. If we compressed distances by the same factor, the planets would be well off-campus: observations. Rocky planets are close together than jovian (gas planets) Sizes of planets are puny compared to distances between them. We can specify distances in the solar system by comparing them to the average earth- 1 au = 150 000 000 km = 150 000 000 000 m. A planet twice as far from the sun would be 2 au away.
