Solar Systems

Defining Astronomy

• Definition → “The study of objects that lie beyond our planet Earth and the processes by which these objects interact with one another”

Scientific Method

• Scientific method: A process to answer questions through empirical study

• Method is iterative: study the problem, make a hypothesis, repeat

Ways to Acquire new Observations

• Build bigger/better telescopes (sharper, more detailed images)

• Look at a different area of the sky or different types of an object (stars/galaxies/planets)

• Look at the same object at different times (short period changes)

Numbers in Astronomy: How do we describe observations with proper notation?

Scientific Notation for Big Numbers:

• Ex 1: 1000 → 10 × 10 × 10 = 10³

• Ex 2: 0.001 → 1/10 × 1/10 × 1/10 = 10^-3

• Ex 3: 53,000,000 = 53 × 1,000,000 = 53 × 10^6

• The AU is defined as the average distance between the earth and the sun, roughly 150 million kilometers

Using the Speed of Light to measure Distance

• Distance Definitions:

  • Use Light-Years (ly) or Astronomical Units (AU)

  • 1 light year = 1 ly

• Earth is 8 light minutes away from the sun

• Earth is 1 AU from the sun

• Usually use AU for solar system objects and ly for objects very far away