Science, humanity and that pale blue dot

An astronomer asks questions about his own planet [24 February 2015 | Peter Boyer]

Twenty-five years ago, on Valentine’s Day 1990, a spaceship took a look back across six billion kilometres to the planet where it had begun its long journey in 1977.

The inner solar system as seen from Voyager 1 on 14 February 1990. Earth is the pale dot in the top coloured band, towards the right of the picture. PHOTO NASA

Part of the inner solar system as seen from Voyager 1 on 14 February 1990. Earth is the pale dot in the top coloured band, slightly towards the right of the picture. PHOTO NASA

Hurtling through space at 1000 km a minute, Voyager 1’s journey was still in its early stages. It was to continue to the edge of the solar system and beyond, into interstellar space. Remarkably, it’s still sending data back to Earth and is expected to continue doing so for another 10 years.

Voyager’s primary mission was to explore Jupiter and Saturn, a task which it completed in 1980. At that point the astrophysicist Carl Sagan suggested to NASA that as it sped away its cameras be turned back toward the sun to obtain a very special image.

As bureaucracies do, NASA took 10 years to agree. In 1990 Voyager captured 60 digital images, stored them on a tape recorder aboard and transmitted them back to Earth over a three-month period. So distant was the spacecraft that it took 5½ hours for the radio signal to reach Earth.

The final image, made from three exposures, showed coloured bands of sunlight reflected off the camera housing. In the middle of one of these bands, taking up less than a pixel in the image, is a tiny dot of light, paler and slightly bluer than surrounding objects.

In 1994, two years before his untimely death, Sagan penned this eloquent tribute to that speck in the photograph: “That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.

“The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilisation, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar’, every ‘supreme leader’, every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.”

All who view this “mote of dust” can’t help but wonder at the smallness of Earth, seen from not even halfway to the edge of the solar system. The pale blue dot as seen from Voyager on its outward journey would soon have disappeared altogether.

The Earth-awareness encapsulated in the Voyager image informs all those who labour in the cause of understanding our universe and our world and all that happens therein. It would have special resonance for the celebrated astronomer Brian Schmidt.

Born in the United States, Schmidt has called Australia home since 1994. His discovery that the universe’s expansion is accelerating brought him the most glittering of prizes for science, the 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics, along with a host of other awards.

Like Voyager, Schmidt is used to looking outward into deep space. But last week, in support of the Australian Academy of Science, he too turned his attention to our own heavenly body. The Academy has just released an update of The Science of Climate Change, its excellent climate booklet for non-specialists.

Schmidt is not surprised at people’s confusion about climate science, which as he points out is a very broad, complex subject. What does surprise him is “the supreme confidence that non-experts (scientists and non-scientists alike) have in their own understanding of the subject”. Whenever climate science comes into a discussion, he finds himself amazed at “how each person I meet suddenly becomes an expert”.

“I too am not an expert on climate science. But I do understand how science works. I understand that the current consensus has been reached by thousands of scientists working for decades.”

They’ve found, he said, that air and oceans are warming, ice is diminishing and sea levels are rising; that human greenhouse gas emissions are the main cause; and that continued emissions will transform Earth’s physical environment and ecosystems.

Schmidt’s plea to his fellow-Australians is that “for the future health of our world and our country, let’s quit self-diagnosing on climate change, and act on the expert opinion.”

In the bigger scheme of things humans don’t even rate a pixel, but here on this pale-blue dot we do matter. It’s us who caused our climate to go awry. We owe it to all of Carl Sagan’s saints and sinners – to ourselves – to fix it.

PHOTO Australian National University

PHOTO Australian National University

A sad postscript: Professor Michael Raupach (left), globally known for his outstanding carbon cycle work and co-editor of The Science of Climate Change, died last week aged 64. I knew him as a humble man, generous with his time and knowledge and unfailingly courteous. He leaves a big gap.

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