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Depositphotos.com |Johan Swanepoel | ERDE Weltall

© © Depositphotos.com |Johan Swanepoel

‘Blue marble’: how half a century of climate change has altered the face of the Earth

In December 1972, Nasa’s final Apollo mission (Apollo 17) took the iconic “Blue Marble” photo of the whole Earth. Many, including science fiction writer Arthur C. Clarke, had expected that the sight of Earth from afar would instil the belief that mankind’s future lay in space.

Instead, it made Earth appear more unique, and has since become an icon of the global environmental movement.

But that portrait is now a historical artefact. Fifty years later, on December 8 2022, Nasa took a new image of Earth from its Deep Space Climate Observatory approximately 1.5 million kilometres away. The photo reveals clear changes to the face of the Earth, some of which are indicative of 50 years of climate change.

Sparked environmentalism

The first photos taken of Earth from space were momentous historical events. In 1966, the robotic Lunar Orbiter 1 (the US’s first spacecraft to orbit the Moon) sent back some early pictures including a black-and-white image of a partly shadowed Earth. The following year, a satellite called ATS-3 took the first colour image of Earth.

Then in 1968, the crew of Apollo 8 became the first humans to see and photograph Earth from space. They took various photos through the capsule’s windows, including the famous photo known as “Earthrise”.

Left: The Blue Marble photo of Earth, taken from Apollo 17 in 1972. Nasa, Author provided (no reuse) | Right: The new Blue Marble, showing visible signs of environmental degradation. DSCOVR/Nasa, Author provided (no reuse)

This photo energised the environmental movement and helped to launch the first Earth Day in 1970. Held on April 22 each year, Earth Day now involves over a billion people worldwide in activities that support environmental protection.

In 1972, Nasa – aware of the public value of Earth images – resolved to capture an image of the whole Earth as Apollo 17 moved away from Earth orbit. Lit by the Sun and taken at a distance of 33,000 km, the photo included the first view of Antarctica from space. The image centred on Africa rather than Europe or America, and became a photographic manifesto for global justice.

The Earth also provided the only visible colour in space. Dominated by blue light, water and clouds, it appeared a unique environment that displayed no signs of human activity. “We live inside a blue chamber, a bubble of air blown by ourselves,” wrote cell biologist Lewis Thomas in 1973.

This was also the decade in which climate scientist James Lovelock put forward the Gaia theory of the Earth as a self-regulating set of combined living and non-living systems. “Earth systems science”, as it is now known, unites scientific understanding of the planet, its biosphere and its changing climate.

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The Conversation 2023

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