Cities of Galaxies
Students learn how galaxies gather into groups, clusters, superclusters and the cosmic web, how hot gas between galaxies glows in X-rays, and how the motions of galaxies in clusters gave the first clues to dark matter.
Grades 5-8About 15 minutes of narrated flight, plus discussion stops8 stops
The full guide, with the 40-minute plan, discussion key points, exit ticket, activities, transcript and PDF, comes with a teacher license. Already licensed? Use Open the full guide.
What students will see and do
Students fly from the Milky Way out to the Local Group, Stephan's Quintet, the Virgo Cluster and its giant galaxy M87, NGC 4889 in the Coma Cluster, and finally the cosmic web. Aetherion pauses at the Local Group (writing a full space address), NGC 4889 (testing explanations for Zwicky's fast-moving galaxies) and the cosmic web (everyday patterns of strands and voids).
Learning objectives
- Describe the hierarchy of galaxy groups, clusters, superclusters and the cosmic web.
- Explain why hot gas in clusters is observed with X-ray telescopes in space.
- Explain how Fritz Zwicky's 1933 measurements of galaxy speeds pointed to unseen mass.
- Use evidence such as gravitational lensing to argue that clusters contain dark matter.
NGSS connections
| MS-ESS1-2 | Gravity holds groups, clusters and superclusters together and shapes the cosmic web. |
|---|---|
| MS-ESS1-3 | Students compare the scale of the Milky Way, the Local Group, clusters and superclusters. |
| MS-PS2-4 | Galaxy speeds reveal how much mass, seen and unseen, is pulling on them. |
Stops on this journey
- Starting from Home
- The Local Group (discussion stop)
- A Tight Little Group
- The Virgo Cluster
- Hot Gas Between Galaxies
- Zwicky and the Coma Cluster (discussion stop)
- Clues to Dark Matter
- Superclusters and the Cosmic Web (discussion stop)
Vocabulary
- galaxy group
- galaxy cluster
- supercluster
- cosmic web
- void
- dark matter
- X-rays
- gravitational lensing