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Life Cycle of Stars

Science · Space Exploration · ages 9-11

Name ______________________ Date ____________

What do stars fuse together in their core to make energy?
- Rock into lava
- Hydrogen into helium
- Water into steam
Where do stars begin their life?
- A nebula, a cloud of gas and dust
- A black hole
- Another star that already exists
A star can shine steadily for millions or even billions of years.
Circle one: True False
A star has been shining brightly for 2 billion years without going out. What is powering it the whole time?
- Fusing hydrogen into helium in its core
- Burning like a campfire burns wood
- Bouncing sunlight off nearby planets
Which comes right before a star begins to shine?
- A black hole shrinking down
- A comet breaking apart
- A nebula pulled together by gravity
Astronomers spot a giant star, twenty times as heavy as the Sun, near the end of its life. How will it most likely end?
- By quietly shrinking into a white dwarf
- In a huge explosion called a supernova
- By turning back into a nebula
Jake says, 'Every single star ends its life by exploding as a supernova.' What is wrong with what Jake said?
- Only massive stars explode; smaller stars shrink into white dwarfs instead
- Stars never end, they shine forever
- Nothing, Jake is completely right
Our Sun is a medium-sized star, not a massive one. Based on what you know, what will most likely happen when it dies?
- It will explode as a supernova
- It will turn back into a nebula exactly as it was before
- It will shrink into a small white dwarf

Answer key

For grown-ups. Fold this page away before handing over the rest.

Hydrogen into helium · Deep in a star's core, hydrogen atoms fuse into helium, releasing energy that makes the star shine.
A nebula, a cloud of gas and dust · Stars start inside nebulae, huge clouds of gas and dust in space.
True · Fusion releases energy slowly and steadily, so a star can keep shining for an extremely long time.
Fusing hydrogen into helium in its core · Stars don't burn like fire. They shine because hydrogen keeps fusing into helium deep in the core.
A nebula pulled together by gravity · Before a star shines, gravity pulls the gas and dust in a nebula together until the center gets hot enough.
In a huge explosion called a supernova · The star is far more massive than the Sun, and only massive stars end in a huge explosion called a supernova.
Only massive stars explode; smaller stars shrink into white dwarfs instead · Jake left out smaller stars. Only the biggest stars explode as a supernova; stars like the Sun become white dwarfs.
It will shrink into a small white dwarf · Only massive stars end in a supernova. A medium-sized star like the Sun shrinks down into a white dwarf instead.