ASTA01H3 Chapter 1: Charting the Heavens
Document Summary
I ntro to astronomy and astro part i. universe: the totality of space, time, matter, and energy. Light-year: a unit for measuring distance, the distanced traveled by light in a year (about 300,000 kilometers per second, typically 10 t rillion kilometers a year) a typical galaxy is a collection of a hundred billion stars, about 100,000 light-years in diameter. distances in space are t ruly astronomical and often hard to wrap your head around such vast distances and sizes. The earliest descriptions of the universe were based largely on mythology and imagination. The power of logical and reasoned arguments grew and the power of myths weakened. They realized that thinking about nature was no longer sufficient looking at it was also necessary. Theory: the framework of ideas and assumptions used to explain some set of observations and make predictions about the real world these theories must be continually tested.
