Cosmic Lifelines Worksheet
Astronomy • The Lives of Stars Independent Work
HOW STARS LIVE AND DIE
Read about how stars are born, how they shine, and how their size decides how they end.
Name:
Period / Date:
Part 1: How Does a Star Stay Alive?
Easy Reading
1. Star Birth: All stars start inside a nebula—a giant, cold cloud of space gas and dust. Gravity pulls the gas into a tight ball called a protostar.
2. Nuclear Fusion: When the center gets super hot, hydrogen gas starts fusing into helium. This releases tremendous heat and light. The star officially turns on! This is the stage our Sun is in.
3. The Great Tug-of-War: For most of its life, a star is in perfect balance: Gravity is pulling everything inward, while Heat from fusion is pushing outward. As long as these two forces are equal, the star stays steady and shines!
The Star Tug-of-War
Core
↓ Gravity Inward ↑ Gravity Inward
Heat & Light Pushing Out ← →
Inward Pull = Outward Push
Part 2: A Star's Size Decides Its Destiny
Use this map to answer questions on Page 2
Track 1 Average Stars (Like Our Sun) — Long Lives (Billions of Years)
Slow & Steady Burn
1. Main Stage
Shines yellow/orange for about 10 billion years.
2. Red Giant
Runs out of core fuel; swells up huge and cools.
3. Gas Cloud Puff
Outer gas rings gently drift away into space.
4. White Dwarf
A tiny, hot leftover core that slowly cools down.
Track 2 Huge Stars (8+ Times Heavier Than Sun) — Short Lives (Millions of Years)
Fast & Furious Burn
1. Blue Giant
Super hot and bright; gulps its fuel very fast.
2. Red Supergiant
Expands into an enormous monster star.
3. Supernova
BOOM! The star collapses and violently explodes.
4. Final Object
Leaves a dense Neutron Star OR a Black Hole.
Part 3: Quick Check
1. In the "tug-of-war" inside a living star, what force pulls inward, and what pushes outward?
2. What is the cloud of gas called where stars are born?
3. Which stars live longer: small stars or giant stars?
Turn to Page 2 for Questions • Page 3 for the Flowchart Drawing Activity
Star Life Cycles • Page 2
PUTTING IT TOGETHER & MYSTERY STAR CASES
Page 2 of 3
Section A: Put the Steps in Order (1 to 4)
Write the numbers 1, 2, 3, and 4 in each box to show the life story of each star from birth (1) to death (4).
Average Star (Like Our Sun)
White Dwarf (tiny leftover core)
Gas Cloud / Baby Star (nebula)
Red Giant (star puffs up big)
Yellow Main Star (shines steadily)
Huge Star (8+ Times Bigger Than Sun)
Supernova (giant explosion)
Gas Cloud / Baby Star (nebula)
Neutron Star or Black Hole (remains)
Red Supergiant (huge puffed star)
Section B: Think and Explain (1–2 Sentences Each)
1. The Gas Tank Puzzle: Huge stars have a lot more gas than small stars. Why do they run out of fuel and die so much faster? (Hint: Think of a giant truck burning gas compared to a small car).
2. Losing the Balance: When a star runs out of hydrogen fuel in its core, it cannot push outward anymore. What will gravity do to the core?
3. "We Are Made of Stardust": When a huge star explodes in a supernova, it scatters elements like iron, carbon, and gold across space. How does that help form new planets and living things?
Section C: Star Detective (What Will It Become?)
Choose from the Word Bank: White Dwarf • Neutron Star • Black Hole
Star Clue #1: Star Barnarda
This star is about the same size as our Sun. It expands into a red giant and puffs off its outer gas.
Final Object:
Star Clue #2: Star Titan-X
This star is 15 times heavier than our Sun. It blows up in a huge supernova explosion, leaving a super-dense ball of neutrons.
Final Object:
Star Clue #3: Star Goliath
A monster star that is 40 times heavier than our Sun. After it explodes, its gravity is so strong that not even light can escape!
Final Object:
Star Life Cycles • Independent Worksheet Turn to Page 3 to draw your Star Life Cycle Flowchart.
Star Life Cycles • Page 3
PART 7: DRAW YOUR STELLAR LIFE CYCLE FLOWCHART
Page 3 of 3
Mission Brief: Draw the Two Star Pathways
In the blank space below, draw and label a complete flowchart of a star's life cycle. Show how both types of stars start from a nebula, and then split into two distinct paths: one path for small/medium stars (like our Sun) and one path for huge stars. Use arrows to show the direction of time!
Path 1 (Small & Medium Stars) Checklist: • Main Stage Star • Red Giant • Gas Puff / Ring • White Dwarf
Path 2 (Giant & Massive Stars) Checklist: • Blue Giant • Red Supergiant • Supernova • Neutron Star / Black Hole
Shared Start at top ↓ Left: Small Stars Path • Right: Large Stars Path Arrows connecting stages →
Star Life Cycles • Visual Flowchart Project Tip: Sketch your shapes with pencil first, then label each stage clearly and add arrows!
