Ch 24: Praxis Earth & Space Sciences: Galaxies & the Universe

About This Chapter

Explore galaxies and the universe through this informative chapter. Prepare for the Praxis Earth and Space Sciences content level exam with this study of stars and universe origins.

Praxis Earth & Space Sciences: Galaxies & the Universe - Chapter Summary

How are stars born? You can learn about neutron, supernova and supergiant stars, and study their beginnings in this chapter. Explore the life cycle of stars, galaxy formation and the theories of the universe's origins, to prepare for the Praxis Earth & Space Sciences content knowledge exam. These lessons can help you gain confidence in the following areas:

  • Formation of stars, including dwarf, giant and main sequence stars
  • Star types by color, size and life cycle
  • Star diagram developed by Hertzsprung and Russell
  • Life cycle of neutron, supernova and supergiant stars
  • Development, relative distances and movement of galaxies
  • Elliptical, spiral and irregular galaxies
  • Black holes' life cycles and dark matter
  • The Big Bang Theory and the timeline of the universe
  • Support of the Big Bang Theory, including red shift of light, background radiation and ongoing expansion

Instructors cover these topics with short, informative video lessons, which include examples to help you understand the subject matter. You'll also find quick quizzes for immediate feedback on your understanding of the topic.

Objectives of Praxis Earth and Space Sciences: Galaxies & the Universe

The topics in this Galaxies & the Universe chapter are part of the astronomy section of your test, which constitutes about 8-12% of the exam. You'll answer 100 multiple-choice questions to complete the test, for which these quizzes can provide meaningful practice. You may choose to take this test in either the computer- or paper-delivered format.

8 Lessons in Chapter 24: Praxis Earth & Space Sciences: Galaxies & the Universe
Test your knowledge with a 30-question chapter practice test
Star Formation: Main Sequence, Dwarf & Giant Stars

1. 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

2. 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.

Life Cycle of Neutron Stars

3. 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.

Supernova and Supergiant Star Life Cycle

4. 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.

Galaxy Formation: Spiral, Elliptical & Irregular Galaxies

5. 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.

Life Cycle of Black Holes

6. 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.

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

7. 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

8. 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.

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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