Elements Forged in Stars

In the picture

1. 1Iron core: the last product of fusion, where the star’s energy runs out
2. 2Inner shells: layers where carbon, oxygen and silicon fuse into heavier elements
3. 3Supernova blast: flings the newly made elements out into space
4. 4Young star and rocky planets: built from gas and dust enriched by the explosion

Examples

• The iron in the haemoglobin of your blood was made in a star that exploded before the Sun existed.
• The oxygen you breathe and the carbon in your food came from fusion inside ancient stars.

Quiz: Elements Forged in Stars (Age 16)

1. 1

   Why does a massive star stop building heavier elements once it has made iron?

   • Iron is pushed to the surface and escapes into space
   • Fusing iron releases no energy, so the star’s energy runs out
   • The star has already used up all its carbon and oxygen
2. 2

   Where did much of the carbon and oxygen in your body originally come from?

   • They were formed inside massive stars, then scattered by supernovae
   • They were made in the Big Bang, along with all other atoms
   • They were produced by chemical reactions in Earth’s early oceans
3. 3

   How are the newly made elements arranged inside a massive star before it explodes?

   • In layers, with the lightest elements at the centre
   • In layers like an onion, with iron at the centre
   • Mixed evenly all the way through the star

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.