Advanced Search

Browse by Discipline

Scientific Societies

E-print Alerts

Add E-prints

E-print Network

  Advanced Search  

ASTR 1120 Section 1 (3 credit hours): Spring 2006 SUMMARY OF KEY CONCEPTS: WEEK #1

Summary: ASTR 1120 Section 1 (3 credit hours): Spring 2006
This is the first of weekly summaries of what I consider to be the key concepts introduced in
class. These summaries are not intended to replace your own notes, and are by no means
inclusive (i.e. anything we've covered in class or in readings from the textbook is `fair game' for
an exam question), but they should help when it comes to reviewing the class for the tests.
Lecture #1
What do we mean by science and what is involved with studying a subject using the `scientific
method'? Science seeks the simplest natural explanation for observed phenomena (note natural
rather than supernatural), and advances via a process of first formulating hypotheses and then
testing them against experiments or new observations. A theory that makes no testable
predictions is not normally regarded as scientific. Chapter 3 of the textbook (either edition)
discusses this in detail.
We then did a super-quick overview of the Universe:
1. The Sun is a star. Stars have a range of masses, and mass is the most important factor
controlling how they evolve. Stars don't live forever (though the lifetime of the Sun,
about 10 billion years, is very long), and when they die they normally eject gas back into
space and leave behind a stellar remnant. If the star is massive enough, this can be a
black hole.
2. A galaxy is an `island of stars' held together by gravity. Our own galaxy, called the Milky


Source: Armitage, Phil - Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder


Collections: Physics