Planets, Stars, Galaxies, and the Universe



About Lesson 3

The first thing I say when I am speaking to younger students about astronomy is that, as a science, there is one very large difference between astronomy and disciplines like physics, chemistry, biology, or the other sciences they may be more familiar with. In astronomy, we are, in almost all cases, prevented from directly experimenting on the objects we are studying. That is, we can never bring a star into a lab and dissect it or otherwise manipulate it to understand how it works. Therefore, astronomers spend their careers studying the light that reaches Earth from objects in space and using that light to learn about the nature of the Universe and the objects in it. So, in this lesson, we will devote a lot of time to describing light, how it is detected, and what it can tell us.

If this difference between the practices of astronomy vs. other sciences interests you beyond the information in the course, our research group has been doing research with K-12 students to study this question recently, and here is an article we published in 2017 on the topic:

Have Astrononauts Visited Neptune?  Student Ideas about how Scientists Study the Solar System

What will we learn in Lesson 3?

By the end of Lesson 3, you should be able to:

  • describe the different types of electromagnetic radiation from radio waves to gamma-rays;
  • explain the relationship between the temperature of an ideal radiator and the amount and type of electromagnetic radiation that it will emit;
  • identify the instruments that astronomers use to detect the light from an astronomical object and explain how to interpret the various methods for displaying a spectrum of light from an object.

What is due for Lesson 3?

Lesson 3 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 following table provides an overview of those activities that must be submitted for Lesson 3. For assignment details, refer to the lesson page noted.

Lesson 3 Activities
Requirement Submitting Your Work
Lesson 3 Quiz Your score on this Canvas quiz will count towards your overall quiz average.
Discussion: The Nature of Astronomical Experiments Participate in the Canvas discussion forum "The Nature of Astronomical Experiments."
Lab 1 You will complete Lab 1 this week and submit it to Canvas.


If you have any questions, please post them to Piazza. 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.