Pictures that changed my view of the Universe
Throughout history, mankind has found enlightenment from various sources – marks on cave walls, stories shared by the fire-side, paintings and sculpture, poetry and drama. Now, photos (or photo-realistic images) can stir some of the most profound moments of enlightenment. The 5 images below had a deeply moving effect on me during my research for How the World came to be. They didn’t all affect me in the same way. Some, such as the Transit of Venus struck me immediately and left me momentarily speechless. Others (e.g. Cosmic Background Radiation) kept coming back to me, gradually revealing deeper and deeper significance each time I looked at them.
The Cosmic Afterglow of Creation
This is an image of variations in the temperature of the cosmic background radiation across the whole sky. The most astonishing thing about this picture is that it is an image of the dawn of creation from 13 billion years ago. It took 400,000 years for the Universe to cool down sufficiently after the Big Bang for electrons to be bound into atoms, hence releasing photons for the first time to produce the first ever light. Travelling through time and across an expanding universe, this light has been stretched into microwave radiation, which is what the Hubble Telescope has mapped in this image. Another astonishing thing about this image is that the hottest (red) parts are a mere 0.002 degrees hotter than the coolest (dark blue) parts. These tiny differences in temperature reflect similarly tiny differences in the density of the early universe – and those differences were all it took for gas clouds to start gathering in some places and not others and for these gas clouds, because of their greater gravity, to get bigger and bigger until they eventually collapsed to form stars and planets.
The First Solid Matter
The Big Bang created a Universe made up of 75% hydrogen and 25% helium (with a few tiny traces of other elements). To get to today’s Universe of over a hundred different elements, including all the solid matter that makes up the world we live in, required the death of other stars before the birth of our own Sun. During the death of those stars, the massive temperatures and pressures produced a cauldron in which progressively bigger elements were created by the nuclear fusion of smaller elements. This runaway chemical reaction culminated in a massive explosion of a super-nova, scattering the newly formed elements across space, to be built into new stars and eventually aggregate into rocky planets like Earth. This image shows the Crab Nebula, which is the remains of a supernova explosion that was first seen on Earth in the year 1054, when it was mistakenly recorded by astronomers as the birth of a new star.
The Solar System is born
Our Solar system formed 4.5 million years ago. It began with a gas cloud so big that it started to collapse under the force of its own gravity. As it collapsed it started to spin and threw out a disk of dust and debris around the increasingly dense centre that turned into the Sun. Gravity kept denser material near the centre of the disk and this became the rocky planets (Mercury, Venus, Earth and Mars). Lighter gaseous material was spun further out and became the giant gas planets (Saturn, Jupiter, Uranus and Neptune). What I love about this image is the deep connection it reveals between us and the rest of the solar system – we are literally all made from the same stuff.
The Collision that made the Moon
Planets formed out of the disk of dust and gas around the young Sun by colliding and merging with one another until they had a clear orbit without bumping into anything else along the way. Earth’s last big collision was with a Mars-sized planet called Theia (named after the greek goddess who was mother of Selene, the Moon goddess). Hitting Earth at an angle, Theia’s heavy iron core was absorbed into the Earth’s core, whereas the rocky mantle of both planets exploded in a cloud of dust and debris reaching far into space. Under the influence of Earth’s gravity, this debris quickly clumped together to form the Moon and entered the stable orbit around us that it has remained in ever since.
The transit of Venus
We’ve been lucky to have 2 transits of Venus in front of the Sun within a decade (2004 and 2012) – it won’t happen again until 2117! I didn’t see the 2004 transit but remember being utterly transfixed by the first pictures I saw. What struck me was the realisation that Venus is the planet closest in size to Earth and seeing it as such a small speck in front of the Sun made me understand how absolutely enormous the Sun is. Planets the size of Venus and Earth are insignificant by comparison.