How can I teach that we are made of stardust?
Explain that most elements in our bodies were made in stars, and show that meteorites contain actual grains of stardust from stars older than the Sun.
The idea that we are made of stardust is inspiring and scientifically accurate. Meteorites provide direct evidence.
Element origins. Hydrogen and most of the helium in the Universe were made in the Big Bang. Heavier elements, including carbon, oxygen, nitrogen, calcium and iron, were made by nuclear fusion inside stars, or in stellar explosions and collisions between dead stars. When stars die, they release these elements into space, where they become part of new clouds that form new stars and planets.
Our bodies. About 96 per cent of the human body by mass is oxygen, carbon, hydrogen and nitrogen. Apart from hydrogen, these were made in stars. The calcium in our bones and the iron in our blood were also made in stars.
Meteorite evidence. Some primitive meteorites contain presolar grains, tiny particles of minerals such as silicon carbide, graphite, diamond and oxides that formed around other stars before the Sun was born. Scientists identify them by their unusual isotope ratios, which match predictions for particular kinds of stars, such as red giants and supernovae. Some grains in the Murchison meteorite may be up to 7 billion years old.
Activity. Pupils colour-code a periodic table to show where each element was made: the Big Bang, small stars, massive stars and exploding stars, or merging neutron stars.
Discussion. How does knowing we are made of stardust change how we think about ourselves?
This topic connects chemistry, physics, biology and astronomy.
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