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Ch 23: The Milky Way Galaxy

About This Chapter

Watch video lessons and learn about the Milky Way galaxy as well as galaxies in general and how they're formed. These lessons are just a portion of our college-level astronomy course.

The Milky Way Galaxy - Chapter Summary and Learning Objectives

The lessons in this chapter are designed to provide you with an up-close tour of our own Milky Way galaxy. Gain an understanding of the typical parts of a galaxy, how galaxies are formed, and how they function. Learn about key astronomical concepts like nucleosynthesis and period-luminosity relation. By the time you complete this chapter, you should be able to:

  • Discuss the nucleus and other major parts of a galaxy
  • Explain why the Milky Way has 'arms'
  • Demonstrate your understanding of dark matter
  • Understand the difference between population I and II stars
  • Define galactic mass

Video Objective
Galaxy Formation: Spiral, Elliptical, and Irregular Galaxies Learn how galaxies are formed by type.
The Formation of the Milky Way GalaxyDescribe the origins of the Milky Way.
The Structure of our Galaxy Learn about the astronomical parts that make up the Milky Way.
The Nucleus of a Galaxy Identify the nucleus and the activity that occurs here.
The Spiral Arms of the Milky Way GalaxyProvide an evidence-based explanation for why the Milky Way has spiral arms.
Population I and Population II StarsDescribe the contours of the Milky Way. Discuss the origins and location of our solar system and how it moves. Provide a brief definition for the following terms: population I and II stars, instability strips, kiloparsecs, nucleosynthesis and period-luminosity relation.
The Mass of Our GalaxyHighlight the differences between the Milky Way galaxy's disk and halo. Demonstrate your understanding of dark matter, including its location.

9 Lessons in Chapter 23: The Milky Way Galaxy
Galaxy Formation: Spiral, Elliptical & Irregular Galaxies

1. Galaxy Formation: Spiral, Elliptical & Irregular Galaxies

This lesson explains how galaxies form, starting with the Big Bang. You'll also learn about the solar nebula hypothesis and three galaxy types, including spiral, elliptical, and irregular galaxies.

The Formation of the Milky Way Galaxy

2. The Formation of the Milky Way Galaxy

This lesson will explore two hypotheses as to how the Milky Way galaxy formed. These are the top-down and bottom-up hypotheses. We'll also go into what special connection you personally have to all of this.

How Our Galaxy Was Discovered

3. How Our Galaxy Was Discovered

This lesson will outline for you the basics of how the galaxy you live in, the Milky Way Galaxy, was discovered over time. You'll also learn about RR Lyrae and Cepheid variable stars.

The Structure of Our Galaxy

4. The Structure of Our Galaxy

If you ever looked up at the night sky far away from city lights, you would've seen a band of light across the night sky and lots of stars scattered around the rest of the sky. Why? The structure of our galaxy will explain exactly why.

The Nucleus of a Galaxy

5. The Nucleus of a Galaxy

This lesson will explore our galaxy's nucleus. Namely, we will find out how we can peer inside using radio waves and infrared, and what that and X-rays tell us about the cool thing that's located inside of it.

The Spiral Arms of the Milky Way Galaxy

6. The Spiral Arms of the Milky Way Galaxy

How do we know our galaxy has spiral arms? You can't really see them, but we can infer they're there thanks to radio waves and observations of other galaxies, which you will learn about in this lesson.

Density Wave Theory & Spiral Galaxies

7. Density Wave Theory & Spiral Galaxies

This lesson will teach you about the spiral arms of the galaxy: namely, the major theory that tries to explain their existence as well as why the spiral arms look so different in various kinds of spiral galaxies.

Population I and Population II Stars

8. Population I and Population II Stars

This lesson will explore the different populations of stars in our galaxy, including population I and II stars, as well as where you can find them and what metals are to an astronomer.

The Mass of Our Galaxy

9. The Mass of Our Galaxy

This lessons explores the estimates and numbers surrounding the mass of the Milky Way Galaxy and how they relate to Keplerian motion, the galactic corona, and dark matter.

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