The magnificent grandeur of the cosmos summons our fascination, our imagination, and our apprehension, as do the majestic objects that occupy it. Even observing the sky on a much smaller scale, one can feel an overwhelming sense of humility. Our very existence is directly connected to the history of the universe. In fact, we are all made of stardust!
A past far beyond yesterday
Around 13.8 billion years ago, an event occurred that marked the beginning of our history: the Big Bang. The fabric of spacetime in which the universe evolves unfolded, giving rise to matter in the form of the first simple atoms. At that time, only hydrogen, the most basic atom, some helium, and a few other simple elements existed. But where was the calcium that makes up our bones? The iron that flows through our veins? The carbon and oxygen in each of our cells? They didn’t exist yet.
For billions of years, many generations of stars punctuated the life of the universe, adding bit by bit to its complexity. At the heart of these gigantic spheres of stellar gas, the temperature and pressure caused atoms to fuse together. This nuclear fusion generated colossal energies, causing the stars to shine, and forging new elements. For example, atoms of hydrogen fused to form helium; helium, in turn, fused to form carbon, and so on. Nitrogen, aluminum, chlorine, iron, etc., all created in the intense nuclear fires at the hearts of stars.
Reborn from the ashes of others
After consuming most of their hydrogen, stars end their lives by dispersing their constituent gases, now richer and more complex, throughout their surroundings. These stellar ashes form the ingredients of the next generation of stars, within which nuclear fusion further enhances the composition of our universe, while the planets that form in orbit around them are born from the same ingredients.
As such, everything we are made of, everything we see, everything we know and love on Earth consists of the remains of stars that preceded us.
Destined to pass it on
And history doesn’t stop here. In a few billion years, our ageing Sun will swell and engulf the first four planets, before dispersing its outer layers light years into space. The Sun, so essential for our survival today, will eventually contribute its enriched remnants to a future generation of stars, around which planets will probably form, giving rise to an infinite world of possibilities.
A must see
See We are Stars, a new animated film for the whole family at the Planétarium.