Planets, Stars, Galaxies, and the Universe



About Lesson 5

Astronomers are able to gather an immense amount of information about stars—their temperatures, their velocities, their distances, their chemical compositions, and also variations in these quantities. Given all of this data, we can construct a physical model for stars that accurately reproduces the observable quantities. The accuracy of our models at reproducing the properties of stars suggests that we understand the internal structure of stars quite well.

Our observations and our theory of stars show us that the stars are not eternal, unchanging objects. Stars follow a lifecycle: they are born, they change slowly as they age, and eventually they die. In this lesson, we are going to focus on the birth of stars and discuss how their lives begin. We will conclude by studying some special cases, including failed stars, bound pairs of stars, and variable stars.

What will we learn in Lesson 5?

By the end of Lesson 5, you should be able to:

  • Describe the process by which stars generate energy in their cores;
  • Describe the forces that keep stars in a stable equilibrium;
  • Qualitatively describe the process of star formation;
  • Describe the early stages of the lifecycle of all stars;
  • Describe how astronomers use binary stars to determine stellar masses.

What is due for Lesson 5?

Lesson 5 will take us one week to complete.

Please refer to the Calendar in Canvas for specific time frames and due dates.

There are a number of required activities in this lesson. The chart below provides an overview of those activities that must be submitted for Lesson 5. For assignment details, refer to the lesson page noted.

Lesson 5 Requirements
Requirement Submitting your work
Lesson 5 Quiz Your score on this quiz will count towards your overall quiz average.
Discussion: Binary Star Evolution Participate in the Canvas Discussion Forum: "Binary Star Evolution".
Unit 2 lab During lesson 5, you will begin work on the HR diagram lab listed under Lab 2, part 1.


If you have any questions, please post them to the General Questions and Discussion forum (not email). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.