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- Test your understanding of each lesson with short quizzes.
- Verify you're ready by completing the life in the universe chapter exam.
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Students will review:
This chapter helps students review the concepts in a life in the universe unit of a standard intro to astronomy course. Topics covered include:
- The universe defined
- Distinguishing among the solar system, galaxy and universe
- The evolution of the universe
- The origins of the universe, including the Big Bang, and the expanding/contracting universes
- The steady state theory vs. the Big Bang theory
- The scale of the universe
- Timescales in the universe
- The observable universe vs. the entire universe
- Comparing the human lifetime to the universe
- The expanding universe: observations and models
- The basic nature of life
- Elements and structure of the universe
- Defining the Big Bang theory in astronomy
- Space, time, matter and energy
- Inflation and acceleration of the universe
- The curvature, age and fate of the universe
- Theories and explanations of the origin of life on Earth
- Timeline and characteristics of the history of life on Earth
- The geologic time scale: major eons, eras, periods and epochs
- Theory of evolution
- Natural selection and adaptation
- Types of natural selection
- Environments where life thrives on Earth
- Making a world habitable
- Fossil evidence for life on Mars
- Planetary predictors of extraterrestrial life
- Pros and cons of space mission types
1. The Cosmological Principle
This lesson will dive into the famous cosmological principle by defining and explaining isotropy and homogeneity as well as their important implications for our universe.
2. How To Calculate the Age of the Universe
This lesson will explain to you how old our universe is and how we calculate it thanks to the Hubble law and Hubble constant as well as one other simple equation.
3. Photons, Particle Soup & Nucleosynthesis
This lesson will explore what happened in the fractions of a second and minutes after the Big Bang occurred. You'll learn about matter, antimatter, photons, deuterons, positrons, and a lot more!
4. Olbers' Paradox & Cosmic Expansion: Nature of the Universe
Why is the night sky dark if there are so many stars in the universe? It used to be thought our universe had several properties that we now know not to be true. This lesson will explain what all that means and why the night sky isn't as bright as the sun.
5. Solar System, Galaxy, & Universe: Definitions & Difference
Want to learn what the universe, galaxy, and solar system are as well as some cool facts about each one? This lesson will give you an overview of what these three things are in a relatable fashion.
6. The Steady State Theory vs. the Big Bang Theory
Did you know that the Big Bang wasn't always a well-accepted theory of our universe? There was a competing theory called the Steady State theory. Find out what it was all about and why its proponent actually helped name the Big Bang theory.
7. The Observable Universe vs. the Entire Universe
This lesson will tie in the concepts of our observable universe, redshift, and the cosmic light horizon to explain why we cannot see the entire universe.
8. Comparing the Human Lifetime to the Universe
Did you ever wonder how long your lifespan actually is compared to the lifespan of the entire universe if it's condensed to one year? This lesson will tell you that and much more.
9. The Basic Nature of Life
What is life? This lesson will attempt to define this and what the basic nature of life is on Earth. We'll go over DNA, RNA, biological evolution, and natural selection.
10. Three Models of the Universe: Flat, Open & Closed
This lesson will describe three models of the universe, including closed, open, and flat, as well as critical density and which model is most likely the correct one.
11. Hot & Cold Dark Matter & WIMPs
Neutrinos, neutralinos, axinos, gravitinos, and what the inos! Dark matter is a crazy thing and there are many different kinds of dark matter. This lesson will go over what they are and what they might be made of.
12. The Universe's Curvature, Age & Fate
What is the age of our universe? What shape does it take? What determines the fate of our universe and what is this fate? This lesson will tell you all of this and more!
13. The Origin of Life on Earth: Theories and Explanations
Ever wonder how living things came from non-living things? We will explore what conditions on early Earth may have created life from non-living items.
14. The History of Life on Earth: Timeline and Characteristics of Major Eras
The Earth is over 4.6 billion years old. Ever wonder what happened during certain time periods in that large amount of time? We will look at the major eons and eras of Earth's history along with important characteristics of each.
15. Geologic Time Scale: Major Eons, Eras, Periods and Epochs
The geologic time scale is an essential tool for understanding the history of Earth and the evolution of life. In this lesson, explore the principal eons, eras, periods, and epochs that help us track major events in geologic history.
16. Theories of Evolution: Lamarck vs. Darwin
We'll look at the interplay between population genetics and environment. Are traits individually acquired or do entire populations evolve? The flying hamsters and a few other notable experiments will provide the answers.
17. Natural Selection & Adaptation: Definition, Theory & Examples
How does natural selection help shape the amazing types of animals we witness around us? In this lesson, we'll explore adaptations and what they can tell us about a species' past evolution.
18. Natural Selection: Definition, Types & Examples
We'll take a look at the types of natural selection that can occur. From flying hamsters to moths, you'll start to grasp the different paths organisms can take as they respond to their changing environments over time.
19. Planetary Predictors of Extraterrestrial Life
Investigate what is needed for life to exist anywhere and the implications for life in our solar system beyond Earth. Consider Mars and some of the moons of Jupiter and Saturn, including Europa, Callisto, Ganymede and Enceladus.
20. Space Mission Types: Advantages & Disadvantages
This lesson will go over four different types of space missions scientists have conducted, including flyby, orbiter, rover, and human space explorations.
21. The Evolution of the Early Universe
This lesson will describe four important stages of development in the early universe, the radiation era, recombination (decoupling) epoch, the dark age, and reionization era.
22. Cosmic Inflation: Solving the Flatness & Horizon Problems
The standard Big Bang theory doesn't explain everything in our universe, namely the horizon problem and flatness problems. This lesson will explain what does, inflation, and how so.
23. The Acceleration of the Universe
The acceleration of our universe is driven by a mysterious dark energy, which can take more than one form. This dark energy helps to explain why our universe is flat.
24. Intelligent Life in Our Universe
This lesson will explore the possibility of finding intelligent life beyond Earth by traveling to it or by detecting its signals, as well as the chances that such life exists in the first place.
25. Is There Life on Other Planets?
This lesson will explore the places and conditions in our solar system and beyond that may make life possible. We'll discuss extremophiles, the habitable zone, Mars, and Europa.
26. Stanley Miller: Theory, Experiment & Apparatus
How did life originate on Earth? We may never have a complete and definite answer to that question, but in 1953, chemist Stanley Miller conducted a famous experiment that would show how the early Earth could have produced the chemicals of life.
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Other chapters within the Intro to Astronomy: Help and Review course
- The History of Astronomy: Help and Review
- How Scientists Think and Work: Help and Review
- Matter, Energy, and Astronomy: Help and Review
- Light in Astronomy: Help and Review
- Newton's Laws in Astronomy: Help and Review
- Rotational Motion and Astronomy: Help and Review
- Orbits, Tides, and Gravity: Help and Review
- Relativity in Time and Space: Help and Review
- Conservation Laws in Astronomy: Help and Review
- Earth's Spheres and Astronomy: Help and Review
- The Earth, Sky, and Moon: Help and Review
- The Moon's Form and Phases: Help and Review
- The Atmosphere on Earth and Other Planets: Help and Review
- Influences on Climate: Help and Review
- The Sun and Energy: Help and Review
- Star Types and Significance: Help and Review
- Measurement of Star Qualities: Help and Review
- The Birth and Life of Stars: Help and Review
- Star Death and Stellar Remnants: Help and Review
- Formation of the Solar System: Help and Review
- Galaxies, Stars and Solar Systems
- Components of the Solar System: Help and Review
- Small Celestial Bodies in the Solar System: Help and Review
- The Milky Way Galaxy: Help and Review
- Characteristics of Galaxies: Help and Review
- Navigation and Timekeeping in Astronomy: Help and Review
- Telescopes: Help and Review