Lesson 5: Galaxies in Motion

How do astronomers measure the motion of galaxies within clusters and groups?

What patterns emerge from observing galaxy collisions and mergers?

How do galaxy interactions affect star formation, shape, and chemical composition?

How can redshift and blueshift be used as tools to study galactic motion?

What does the motion of galaxies tell us about the large-scale structure of the universe?

Redshift

Blueshift

Doppler effect

Galaxy cluster

Galactic merger

Recessional velocity

Cosmic expansion

Spiral galaxy

Elliptical galaxy

Large-scale structure

HS-ESS1-2 – Use astronomical observations, including redshift measurements, to support explanations of galaxy motion, interactions, and the evolution of large-scale cosmic structures.

NGSS Crosscutting Concepts

Cause and Effect

Systems and System Models

Patterns

Stability and Change

Students will interpret redshift and blueshift data to analyze galaxy motion within clusters.

Students will examine observational evidence of galaxy collisions and mergers to explain structural changes.

Students will develop analytical and reasoning skills by connecting observations to models of galaxy evolution.

Students will explore how galaxies move, collide, and merge, and how these interactions shape the evolution of galaxies over time. The lesson emphasizes galactic dynamics within clusters and groups rather than the universe’s overall expansion. Students will analyze redshift and observational data as a tool to understand these processes.

Activities may include:

Plotting galaxy velocities within clusters using redshift/blueshift data

Observing simulations of galaxy collisions and mergers

Comparing real galaxy images to simulation outcomes to identify structural changes

Purpose: Reinforce understanding of cause-and-effect relationships in galaxy interactions, emphasizing the role of observations in modeling galactic evolution.
DOK Level: 3 – Strategic Thinking / Reasoning (analyzing patterns, interpreting data, constructing evidence-based explanations)

Connects to ongoing astronomical research using Hubble, James Webb, and other telescopes to study galaxy clusters and mergers.

Highlights the collaborative international nature of galaxy research.

Students can relate galaxy interactions to element formation and starburst activity, connecting to questions about the origin of stars, planets, and potentially life-supporting elements.

Students may think galaxies move independently through static space rather than within gravitational systems and clusters.

Students may believe all collisions are destructive rather than often triggering new star formation.

Students may confuse redshift with actual color changes of galaxies.

Students may assume galaxy evolution is a uniform process rather than highly dependent on interactions and environment.

Scaffolded instruction for interpreting redshift and blueshift data in galaxy clusters.

Graphic organizers to map galaxy motion, interactions, and mergers.

Technology integration: simulations of galaxy collisions, mergers, and cluster dynamics.

Peer collaboration for analyzing images and constructing explanations of galaxy evolution.

Step-by-step guidance for connecting observations to cause-effect relationships in galactic systems.

Support for interpreting both visual and numerical astronomical data.

• Checkpoints during galaxy velocity plotting and simulation analysis.

• Quizzes on key vocabulary and galaxy motion concepts.

• Evaluation of student-created diagrams or models showing galaxy interactions and mergers.

• Constructed-response assignments explaining how observational evidence supports models of galaxy evolution.

• Astronomy slides and worksheets on galaxy motion, collisions, and mergers

• Redshift/blueshift datasets for classroom analysis

• Simulations of galaxy collisions, mergers, and cluster dynamics

• Images of interacting galaxies and clusters from Hubble and JWST

• Articles or case studies on galaxy mergers, starburst activity, and large-scale structure