En anglais

The Life Cycle of a Star

Science · Space Systems & Earth's History · ages 13-14

Name ______________________ Date ____________

Which two endings are possible only for very massive stars?
- White dwarf or red giant
- Neutron star or black hole
- Nebula or protostar
Look at the star's life cycle below. What is stage 1, the highlighted stage, called?
- Nebula
- Red giant
- White dwarf
Nuclear fusion inside a star can build elements heavier than hydrogen and helium.
Circle one: True False
A star ten times heavier than the Sun finally runs out of fuel. What happens next?
- It explodes as a supernova, leaving a neutron star or black hole
- It quietly shrinks into a white dwarf
- It turns back into a nebula
Put these stages of a Sun-like star in the order they happen.
- Red giant, then nebula, then main sequence
- Main sequence, then nebula, then red giant
- Nebula, then main sequence, then red giant
Count the stages shown in this Sun-like star's life cycle. How many stages are there?
Answer: ______________
Two stars start as identical nebulae, but Star A is far more massive than Star B. What happens to each?
- Both stars will always end the same way, since they started the same way
- Star B will explode first because smaller stars burn fuel faster
- Star A is more likely to end in a supernova and leave a neutron star or black hole, while Star B likely becomes a white dwarf
A classmate says the iron in your blood came from the Sun exploding. What's the mistake?
- Iron does not come from stars at all
- The Sun isn't massive enough to explode as a supernova; the iron came from a different, more massive star that died long ago
- The Sun already exploded when the solar system formed

Answer key

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

The Life Cycle of a Star W1-mt_lHasFmgvnT-s1

Neutron star or black hole · Massive stars explode as a supernova and leave behind a neutron star or, if massive enough, a black hole.
Nebula · Every star's life starts inside a nebula, a cloud of gas and dust pulled together by gravity.
True · Fusion fuses lighter atoms into heavier ones, like carbon, oxygen, and iron.
It explodes as a supernova, leaving a neutron star or black hole · Only stars far more massive than the Sun end their lives in a supernova.
Nebula, then main sequence, then red giant · A star starts as a nebula, spends most of its life on the main sequence, then swells into a red giant.
5 · Nebula, protostar, main sequence, red giant, and white dwarf: five stages in all.
Star A is more likely to end in a supernova and leave a neutron star or black hole, while Star B likely becomes a white dwarf · A star's mass decides its ending: heavier stars burn fast and end dramatically, while lighter stars like the Sun end quietly.
The Sun isn't massive enough to explode as a supernova; the iron came from a different, more massive star that died long ago · Sun-like stars end quietly as white dwarfs. Making enough iron takes a supernova from a much more massive star.