GED® Science: Stars, Galaxies & the Universe
From the star next door to the edge of the observable universe — this course covers the astronomy portion of the GED® Earth & Space Science domain. You will learn how stars are born, live, and die; how the Hertzsprung-Russell diagram classifies stars by temperature and brightness; what our Milky Way galaxy looks like and how it fits into the larger universe; the evidence for the Big Bang and an expanding universe; and how astronomers measure cosmic distances. Every lesson uses real-world analogies, labeled diagrams, and GED®-style multiple-choice practice with full explanations.
📚 Course Curriculum
Stars are not permanent. Like living things, they are born, they age, and they die — but on timescales of millions to billions of years. …
🔒 Enroll to unlock this session.
Not all stars look the same in the night sky — some are bright, some dim, some bluish-white, some orange-red. These differences reflect real physical …
Open trial session →The Hertzsprung-Russell (H-R) diagram is one of the most important tools in astronomy. It plots stars by two properties:. X-axis: surface temperature (note: temperature *decreases* …
🔒 Enroll to unlock this session.
A galaxy is a massive system of stars, gas, dust, and dark matter held together by gravity. Our home galaxy is called the Milky Way. …
Open trial session →The Milky Way is just one of an estimated 2 trillion galaxies in the observable universe. Types of galaxies:. Type Shape Example. Spiral Flat disk …
Open trial session →How did the universe begin? The most widely supported scientific explanation is the Big Bang theory. Key idea: approximately 13.8 billion years ago, the entire …
🔒 Enroll to unlock this session.
Measuring cosmic distances:. Space is so large that ordinary units (km, miles) become unworkable. Astronomers use:. Light-year (ly): the distance light travels in one year …
🔒 Enroll to unlock this session.
Course Syllabus
This self-paced GED® Science course follows a 7-lesson sequence. Work through the modules in order so that each skill supports the next.
Course sequence
Module 1 - Lessons 1-4
- The Life Cycle of a Star
- Properties of Stars: Temperature, Color, and Brightness
- The Hertzsprung-Russell (H-R) Diagram
- Our Galaxy: The Milky Way
Module 2 - Lessons 5-7
- Beyond the Milky Way: Galaxies and the Large-Scale Universe
- The Big Bang and the Expanding Universe
- Light-Years, Cosmic Scale, and Reading Astronomical Data
Practice and completion
- Use worked examples and lesson practice to check understanding after each module.
- Review incorrect answers, explain the correction, and repeat weak skills.
- Complete the available mixed or final course practice to demonstrate readiness.
Course Outcomes
By the end of this course, learners will be able to:
- Explain the key scientific ideas and vocabulary in The Life Cycle of a Star.
- Interpret observations, data, models, or evidence related to The Hertzsprung-Russell (H-R) Diagram.
- Apply scientific reasoning to questions involving Our Galaxy: The Milky Way.
- Evaluate explanations and identify common errors about Beyond the Milky Way: Galaxies and the Large-Scale Universe.
- Connect Light-Years, Cosmic Scale, and Reading Astronomical Data with other course concepts in mixed practice.
- Use feedback and answer explanations to diagnose and correct mistakes.
- Complete mixed, exam-style practice with clearer reasoning and greater independence.
📝 Practice Questions
23 interactive questions with instant feedback and explanations.
Enroll for free to unlock the full practice bank after the trial sessions.