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Ch 23: Stars, Galaxies & the Universe

About This Chapter

Use our video lessons and quizzes to help you understand theories of how the universe formed. Learn about neutron stars, black holes, supernovas, and more.

About This Chapter

In this chapter, video instructors show you current theories about the origins of the universe, including the Big Bang Theory and theories about expanding and contracting universes. You'll be introduced to Tycho Brahe and Nicolaus Copernicus and learn about their contributions to knowledge of the universe in their times. This chapter will discuss evidence for the Big Bang Theory - including background radiation, red shift, and expansion.

You'll learn about the formation of spiral, elliptical, and irregular galaxies and of dwarf and giant stars, as well as the typical star formation process. As you progress through the chapter, you'll learn about the life cycles of black holes, neutron stars, supernovas, and red giants. When you finish this chapter, you should be able to:

  • Evaluate the characteristics and supporting evidence of the various theories of cosmology and cosmogony
  • Distinguish different types of stars by size, color, and life cycle
  • Understand galaxy and star formation
  • Recognize the historical progression of astronomy and the physical laws that govern it

These video lessons are written to be short enough to keep you engaged, yet detailed enough that you can learn the most important facts about each topic. To make these videos easy to use, take advantage of the tags that allow you to toggle between the most important points. If you get stuck on an unfamiliar keyword, just click on it; key terms link to text lessons with further information. After watching each video lesson, you'll have the opportunity to take a self-assessment quiz so you can gauge how well you understood the material.

9 Lessons in Chapter 23: Stars, Galaxies & the Universe
Test your knowledge with a 30-question chapter practice test
Origins of the Universe: The Big Bang and Expanding & Contracting Universes

1. 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.

Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion

2. Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion

Discover what evidence exists to support the Big Bang theory of the birth of the universe. Learn how cosmic background radiation, the red shift of light and the ongoing expansion of the universe led scientists to believe that the universe was started with the Big Bang.

Galaxy Formation: Spiral, Elliptical & Irregular Galaxies

3. 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.

Star Formation: Main Sequence, Dwarf & Giant Stars

4. Star Formation: Main Sequence, Dwarf & Giant Stars

Learn how stars are born, beginning with a protostar. Then learn about stars in later stages of life, including main sequence stars, brown dwarfs, red giants, and black holes.

Types of Stars by Size, Color and Life Cycle

5. 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.

Supernova and Supergiant Star Life Cycle

6. Supernova and Supergiant Star Life Cycle

Learn about one of the biggest explosions known to humankind - a supernova. Follow a star's life cycle and learn how a star changes from a red giant to a supernova to a black hole or neutron star.

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.

Life Cycle of Neutron Stars

8. Life Cycle of Neutron Stars

Discover the life of a neutron star, including how it's born after a supernova explosion and how its extreme pressure causes protons and electrons to combine into neutrons. Discover also how pulsars are rotating neutron stars that will eventually slow down to become regular neutron stars.

Tycho Brahe and Copernicus Take On the Known Universe

9. Tycho Brahe and Copernicus Take On the Known Universe

Astronomy according to Ptolemy was the popular theory until Copernicus turned it on its head. This lesson explores the theories of Copernicus and Brahe and how the two changed astronomical study.

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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