When Galaxies Collide

Students learn what happens when galaxies collide: stars almost never hit each other, but gas clouds crash and spark new star formation, and gravity pulls stars into long tidal tails. They also learn that the future meeting of the Milky Way and Andromeda is a real but uncertain prediction.

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 above the Milky Way to the Antennae Galaxies, Stephan's Quintet, the Whirlpool Galaxy, the Cigar Galaxy, the Large Magellanic Cloud and Andromeda, then return home. Aetherion pauses at the Antennae Galaxies (why colliding gas makes new stars), the Cigar Galaxy (fast change caused by a nearby disturbance) and Andromeda (why scientists update predictions).

Learning objectives

• Explain why stars rarely collide when galaxies merge, using the scale of space between stars.
• Describe how gravity creates tidal tails and how colliding gas clouds trigger star formation.
• Compare a close pass (Whirlpool, Cigar) with a full merger (Antennae).
• Use evidence to explain why predictions about the Milky Way and Andromeda have changed.

NGSS connections

Stops on this journey

1. Your Galaxy, Mostly Empty
2. The Antennae (discussion stop)
3. Stephan's Quintet
4. The Whirlpool and Its Partner
5. The Cigar Galaxy's Starburst (discussion stop)
6. A Small Neighbor Nearby
7. Andromeda Is Coming (discussion stop)
8. A Possible Future

Vocabulary

• galaxy
• tidal tail
• merger
• starburst galaxy
• gas cloud
• star formation
• dwarf galaxy
• supernova