Ch 41: Galaxies & the Universe

About This Chapter

To review scientific concepts related to the universe and its galaxies, look no further than this comprehensive astronomy chapter. You can use these lessons to study star types, light years, black holes and the origins of the universe.

Galaxies & the Universe - Chapter Summary

In this astronomy chapter, our expert instructors cover essential topics related to galaxies and the universe. These short and engaging video and text lessons can help you identify the characteristics of galaxies and study the different types of stars that occupy them. You'll also learn how to find the size of a star and get acquainted with the Big Bang and Contracting Universe theories. After completing the chapter, you should be able to:

  • Explain what a galaxy is
  • Identify the stars and center of the Milky Way Galaxy
  • Differentiate star types by size, color and life cycle
  • Summarize the life cycle of average stars and black holes
  • Describe planetary nebulae
  • Define astronomical units and light years
  • Understand the theories related to the origins of the universe

These lessons offer a quick and efficient method for reviewing important astronomy topics. Lessons are generally less than ten minutes in length and included highlighted definitions and memorable examples. Self-assessment quizzes are available to take after you finish each lesson and you can print our lesson transcripts to supplement your study. If you need to review a concept that's unclear, you can easily find the topic using our interactive course Dashboard. To make the learning experience convenient, we've made the chapter accessible on any computer or mobile device and available at any time that fits your schedule.

9 Lessons in Chapter 41: Galaxies & the Universe
Test your knowledge with a 30-question chapter practice test
Galaxy: Definition & Explanation

1. Galaxy: Definition & Explanation

Galaxies are collections of stars, dust, and gas rotating around super massive black holes. This lesson will cover the structures and types of galaxies, including spiral, elliptical, and irregular galaxies.

The Milky Way Galaxy: Stars, Center & Pictures

2. The Milky Way Galaxy: Stars, Center & Pictures

Our galaxy, the Milky Way, is home to our sun, along with around 250 billion other stars. This lesson will cover the features of our galaxy and provide a quiz at the end to test your knowledge.

Types of Stars by Size, Color and Life Cycle

3. Types of Stars by Size, Color and Life Cycle

Learn to identify the different sizes and colors of stars and how they relate to the star life cycle. In this lesson, we'll talk about spectral classification, how many stars there are of each type and the approximate color of the different classes of stars.

Average Star: Definition & Life Cycle

4. Average Star: Definition & Life Cycle

Stars come in all sorts of colors and sizes, but many of them are actually quite similar. This lesson will shed some twinkling light on the characteristics and life cycle of the average sun-like star.

How to Find the Size of a Star

5. How to Find the Size of a Star

This lesson will tell you how astronomers figure out the size of stars. You'll learn it has to do with a star's temperature, luminosity, and a cool thing known as the H-R diagram.

What Are Planetary Nebulae?

6. What Are Planetary Nebulae?

This lesson will define something very cool and beautiful called a planetary nebula. You'll not only learn what it is but how it's formed, and why it produces all those amazing colors!

Life Cycle of Black Holes

7. Life Cycle of Black Holes

Learn about black holes, their myths and their reality. Learn how black holes form after stars undergo supernovae and create singularities. Discover how big black holes grow, how scientists find black holes and where black holes are located in the universe.

Astronomical Units & Light Years: Definition & Examples

8. Astronomical Units & Light Years: Definition & Examples

After watching this video, you will be able to explain why we need special astronomical ways of measuring distance. You will also be able to state the meaning of the terms astronomical unit, light year and parsec. A short quiz will follow.

Origins of the Universe: The Big Bang and Expanding & Contracting Universes

9. Origins of the Universe: The Big Bang and Expanding & Contracting Universes

Students will learn the origins of the universe, the Big Bang theory, the timeline of the universe, how the universe is still expanding to this day, and what astronomers expect the universe to look like in the future.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
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Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
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Other Chapters

Other chapters within the Pennsylvania Grades 4-8 - Science Subject Concentration (5159): Practice & Study Guide course