You are made of stardust

The elements that make up our bodies were forged inside ancient stars…


nebula human elements

                                                    “We are made of starstuff” – Carl Sagan


Hydrogen is the smallest element, and formed in vast quantities after the Big Bang, along with a less plentiful supply of helium, and even smaller amounts of lithium and beryllium. But making the heavier elements required more energy.

Hydrogen and helium gas clumped together to form clouds, and these clouds collapsed to form stars with enough heat and pressure to trigger nuclear fusion; inside the stars, the nuclei of hydrogen atoms slammed together, fusing to form helium. As the stars aged, the helium atoms started to create even heavier elements, including carbon, nitrogen and oxygen.

Depending on the mass of the star, this process sometimes continued, producing the nuclei of most of the elements up to number 26, iron. After this critical point, fusion reactions stop releasing energy. When stars run out of useable fuel, they collapse, kicking layers of gas and heavy elements out into space.

For the most massive stars, this process involves a powerful explosion called a supernova, which provides enough energy to make the elements that are heavier than iron. The remnants of these old exploded stars mix with yet more hydrogen gas and go on to make more star systems, like our own Sun and planets, providing us with the range of elements we have on Earth today.


Article extract from “Your Guide to the Elements” by Laura Mears in How It Works issue 81, available now from the Imagine Shop

Images: Thinkstock; NASA, ESA, and the Hubble SM4 ERO Team


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