Question: For my senior research project I am doing what aspects of astronomy are theory and what are fact. The question I pose is what are different theories I could use for this topic? I already have the theory of the expanding universe and also the theory of black holes. I just need one more. Your help is much appreciated. Thanks! – Caitlyn
Answer: Theory and fact (or observation) really go hand-in-hand. You really cannot have one without the other. Observations are used to support theories, while theories are the connections between what observations tell us about astrophysical objects and what the physical understanding of an object is. You already have two good theories; the theory of the expanding universe and the theory suggesting the existence of black holes. Here are some more theories:
- Formation of the solar system
- Formation of the Milky Way galaxy
- Stellar formation and evolution (or how stars are born and ultimately die)
Note that all of these theories have substantial observational “underpinnings”, so that most of them are widely accepted as fact by astrophysicists.