Galaxies

Astronomy

Literacy / Driving Question Board Connections

Nonfiction Science Literacy Resources

Graphic Organizers / Thinking Maps

Driving Question Boards

Multilingual Learner Language Expectations

Citizen Science Opportunities

Galaxies

Today, we know that our Sun is just one of the many billions of stars that make up the huge cosmic island we call the Milky Way Galaxy. How can we “weigh” such an enormous system of stars and measure its total mass?

One of the most striking features you can see in a truly dark sky—one without light pollution—is the band of faint white light called the Milky Way, which stretches from one horizon to the other. The name comes from an ancient Greek legend that compared its faint white splash of light to a stream of spilled milk. But folktales differ from culture to culture: one East African tribe thought of the hazy band as the smoke of ancient campfires, several Native American stories tell of a path across the sky traveled by sacred animals, and in Siberia, the diffuse arc was known as the seam of the tent of the sky.

In 1610, Galileo made the first telescopic survey of the Milky Way and discovered that it is composed of a multitude of individual stars. Today, we know that the Milky Way comprises our view inward of the huge cosmic pinwheel that we call the Milky Way Galaxy and that is our home. Moreover, our Galaxy is now recognized as just one galaxy among many billions of other galaxies in the cosmos.

Suggested Course Sequence

Chapter 24 Black Holes (sections 5 & 6 only)
Chapter 25 The Milky Way
Chapter 26 Galaxies • [optional: Chapter 27. Quasars (in any case, you can omit section 3)]
Chapter 28 Evolution and Distribution of Galaxies
Chapter 29 Cosmology (omit sections 6 and 7 if short on time)
Chapter 30 Life in the Universe (briefly)

Openstax Astronomy Online Text

Unit Standards

What is the NGSS & 3 Dimensional Science Learning and Why is it Important?

Science Practices - Disciplinary Core Ideas - Crosscutting Concepts

HS-ESS1-1: Nuclear Fusion and the Sun's Energy

Develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun’s core to release energy in the form of radiation. (Scale, Proportion, and Quantity)

Clarification Statement: Emphasis is on the energy transfer mechanisms that allow energy from nuclear fusion in the sun’s core to reach Earth. Examples of evidence for the model include observations of the masses and lifetimes of other stars, as well as the ways that the sun’s radiation varies due to sudden solar flares (“space weather”), the 11-year sunspot cycle, and non-cyclic variations over centuries.

Boundary Statement: Assessment does not include details of the atomic and sub-atomic processes involved with the sun’s nuclear fusion.

HS-ESS1-2: The Big Bang Theory

Construct an explanation of the big bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe. (Energy and Matter)

Clarification Statement: Emphasis is on the astronomical evidence of the red shift of light from galaxies as an indication that the universe is currently expanding, the cosmic microwave background as the remnant radiation from the Big Bang, and the observed composition of ordinary matter of the universe, primarily found in stars and interstellar gases (from the spectra of electromagnetic radiation from stars), which matches that predicted by the Big Bang theory (3/4 hydrogen and 1/4 helium).

Boundary Statement: none

HS-ESS1-3: Stellar Nucleosynthesis

Communicate scientific ideas about the way stars, over their life cycle, produce elements. (Energy and Matter)

Clarification Statement: Emphasis is on the way nucleosynthesis, and therefore the different elements created, varies as a function of the mass of a star and the stage of its lifetime.

Boundary Statement: Details of the many different nucleosynthesis pathways for stars of differing masses are not assessed.

HS-ESS1-4: Orbital Motions

Use mathematical or computational representations to predict the motion of orbiting objects in the solar system. (Scale, Proportion, and Quantity)

Clarification Statement: Emphasis is on Newtonian gravitational laws governing orbital motions, which apply to human-made satellites as well as planets and moons.

Boundary Statement: Mathematical representations for the gravitational attraction of bodies and Kepler’s Laws of orbital motions should not deal with more than two bodies, nor involve calculus.

Learning Objectives / Career Connections

By the end of this chapter, students should be able to:

Chapter 24

Discuss some of the key ideas of the general theory of relativity
Recognize that one’s experiences of gravity and acceleration are interchangeable and indistinguishable
Distinguish between Newtonian ideas of gravity and Einsteinian ideas of gravity
Recognize why the general theory of relativity is necessary for understanding the nature of black holes

Chapter 25

Explain why William and Caroline Herschel concluded that the Milky Way has a flattened structure centered on the Sun and solar system
Describe the challenges of determining the Galaxy’s structure from our vantage point within it
Identify the main components of the Galaxy

Chapter 26

Describe the discoveries that confirmed the existence of galaxies that lie far beyond the Milky Way Galaxy
Explain why galaxies used to be called nebulae and why we don’t include them in that category any more

Chapter 28

Explain how astronomers use light to learn about distant galaxies long ago
Discuss the evidence showing that the first stars formed when the universe was less than 10% of its current age
Describe the major differences observed between galaxies seen in the distant, early universe and galaxies seen in the nearby universe today

Chapter 29

Describe how we estimate the age of the universe
Explain how changes in the rate of expansion over time affect estimates of the age of the universe
Describe the evidence that dark energy exists and that the rate of expansion is currently accelerating
Describe some independent evidence for the age of the universe that is consistent with the age estimate based on the rate of expansion

Chapter 30

Describe the chemical and environmental conditions that make Earth hospitable to life
Discuss the assumption underlying the Copernican principle and outline its implications for modern-day astronomers
Understand the questions underlying the Fermi paradox

Using ChatGPT to find local Colorado Phenomena

Use the following prompt, adjust accordingly. "I am a high school science teacher looking for a local Colorado phenomena to address NGSS standard (enter standard you are looking for... example HS-LS1-6)"

Career Connections

Connecting what students are learning to careers not only deepens their engagement in school but also helps them make more informed choices about their future. Browse the following related career profiles to discover what scientists really do on the job and what it takes to prepare for these careers. For additional profiles visit your Year at a Glance Page.

Hands On, Minds On Connections

Hands-On Labs / Lab Safety

St Vrain Science Center

Chapter 7 Introduction to the Solar System
Chapter 9 The Moon (omitting Mercury)
Chapter 10 Venus and Mars
Chapter 11 Giant Planets
Chapter 12 Rings, Moons, and Pluto (at least Pluto, briefly)
Chapter 14 Origin of Solar System [do Section 3 on the Formation of the Solar System only]

Simulations

GIZMOS

Gizmos in Science

Nearpod Lessons / Activities / Videos

LabXchange Lessons / Activities / Videos