The universe is the whole of space and everything it contains, including the most distant stars, every planet and their moons, all on Earth, even you.

The story of our universe began around 13.8 billion years ago. Cosmos, then the size of a minuscule dot, contained all the existing matter, therefore being incredibly dense and hot. In what is known as the Big Bang, the universe began to expand and cool down, and our time to tick.

For the first few hundred thousand years, the universe was an endless sea of swirling particles until it became cool enough for the first atoms¹ to exist. From electrons, neutrons, and protons came into being hydrogen, helium, and a modicum of lithium, the three simplest and lightest elements that could stand the surrounding heat.

Time passed a hundred million years more before the temperature of our ever-expanding universe allowed the three atoms not only to exist but to move. Floating around in the dark space, they began to clump up into increasingly larger structures, creating the first stars that lit up the universe.

Stars became the factories of the universe. From only the three existing ingredients, they forged all the rest, a hundred or so atoms that make up the structures of everything – you and me, whatever we can see and touch, all on Earth and in space.

Over time, atoms began to coalesce into molecules, which teamed up into planets and moons. Moons began to orbit planets, and planets to orbit stars, creating planetary systems, which clustered further into hundreds of billions of galaxies, each consisting of billions upon billions of stars, planets and moons.

¹ An atom is the smallest part of an element, with identical chemical properties of that element. An atom has a nucleus consisting of protons and neutrons, and the nucleus is orbited by electrons. The number of protons defines the atom's identity. Atoms with one proton are hydrogen, atoms with two protons are helium and atoms with three protons are lithium – each time you add a proton, you get a new element. Atoms bond with each other by sharing, giving, or taking electrons, creating more complex structures together – molecules. For example, when an oxygen atom shares electrons with two hydrogen atoms, a water molecule comes into being. Today, humans have discovered 118 atoms, of which around 90 occur naturally on Earth, the rest created by scientists. Atoms are neatly organized in a Periodic Table.

Bibliography

Cohen, A. & Cox, B. 2023. The Universe. Dublin, Ireland: HarperCollinsPublishers. 272 p. ISBN 9780008389352. Pages 72, 78, 80, 83-92, 115, 242-251.

DK. 2021. Science the Definitive Visual Guide. London, United Kingdom: Dorling Kindersley. 520 p. ISBN 9780241446331. Pages 232-233, 286-289, 320-321, 494.

Dartnell, L. 2019. Origins How the Earth Shaped Human History. London, United Kingdom: Penguin Random House. 346 p. ISBN 9781784705435. Page 167.

Oja, H. 2018. Maailmankaikkeuden Rakenne. Helsinki, Finland: Tähtitieteellinen yhdistys Ursa. 95 p. ISBN 9789527443101. Pages 11-15.

Bryson, B. 2003. A Short History of Nearly Everything. London, United Kingdom: Transworld Publishers. 668 p. ISBN 9781784161859. Pages 175-176, 183-184.

Harari, Y. N. 2015. Sapiens: A Brief History of Humankind. London, United Kingdom: Vintage. 512 p. ISBN 9780099590088. Page 3.

Next Story

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Milky Way Galaxy forms

Just a few hundred million years after the Big Bang, our spectacular galaxy began to form around a supermassive black hole. Over time, the Milky Way has grown to contain over 100 billion stars, if not multiple times more, only a few thousand closest and brightest we can see with our naked eyes from any point on planet Earth.