SCIENCE AND THE EARTH
In Understanding the Earth (Understanding Science), Tom takes the reader on an oftentimes enthralling–always incisive and thoroughly inquisitive–journey deep into the very fibres of the fabric from which our world, and the universe itself, are formed.
From the structure of the earth to the atmosphere that has helped to furnish our planet with life, through to the seismic and catastrophic natural events that have shaped the course of evolution as we understand it, Tom leaves no stone unturned.
Understanding the Earth (Understanding Science), and other works by Tom Williamson, which explore the nature of the earth we inhabit, are available to buy now via Amazon.
BORN OF STARDUST...
We are earthlings born of stardust. The hydrogen atoms that make up about ten per cent of our bodies by weight were made in the Big Bang about fourteen billion years ago, as were traces of helium, lithium and beryllium.
But the oxygen, carbon, nitrogen and other atoms of our bodies formed later from hydrogen and helium as these ingredients and their fusion products stewed at high temperatures deep inside stars.
Later ejected from such stellar pressure cookers, some of these atoms linked to form molecules or tiny crystals and became part of the solar nebula that gave birth to the earth around 4.6 billion years ago.
THE IMPORTANT ROLE OF ATOMS
NGC 2392, the Eskimo Nebula in Gemini.
This glowing shell of ionised gas includes atoms such as carbon, nitrogen, oxygen and silicon made by fusion from hydrogen and helium deep inside the central star.
Many of the Earth’s heavier atoms, including most of those in our own bodies, apart from hydrogen, were made in this way.
Hubble Space telescope
Courtesy NASA/ESA
THE STORY OF LIFE'S CREATION
These space molecules included several carbon-based molecules such as the amino acid glycine (above) which are among the building blocks of life. So, our first living ancestors may have been space travellers, brought to earth not in alien spacecraft but in comets or meteorites.
Whether they came from space, first evolved on another planet such as Mars, or originated in aqueous earthly environments like terrestrial or submarine hot springs, by around two billion years ago some of our earliest single-cell water-dwelling ancestors had banded together to form eukaryotic cells with organelles and nuclei.
A DESTRUCTIVE PLANET
Our planet hasn't always remained friendly to life. Many times in the past - for example around 300, 65 and 55 million years ago - events such as massive volcanic activity, impacts of asteroid-sized bodies and oceanic methane bursts have triggered rapid changes in the earth's climate system.
These climatic disasters have typically involved the rapid release of warming greenhouse gases. Some of them have led to mass extinctions of species.
Photo:
Mount Pinatubo, Philippines, erupted in June 1991, injecting sulphate aerosols into the upper atmosphere and temporarily cooling Earth’s climate. Courtesy U.S. Geological Survey
