Ten years ago today, Carl Sagan, one of the greatest humans of the 20th century died. What he did for humanity is too vast to cover in this post, he was awarded the Konstantin Tsiolkovsky Medal of the Soviet Cosmonauts Federation, the Public Welfare Medal and NASA's Exceptional Scientific Achievement award among many many others. What he gave back to human society is incalculable.

Although he was less well known in Britain then other countries, Patrick Moore has always been our "astronomer-guy" in the public mind. What I admire the most about Carl was his ability to show the awe and wonder of the cosmos, something very few people have been able to do, this was really his one single greatest attribute in my mind.

He was also not afraid to tackle social and political issues, especially when it came to nuclear weapons which under Reagan were being expanded along with the proposed development of SDI. When the Soviet Union announced that it would freeze all development of nuclear weapons, Carl was arrested twice as protests against the US government were called when they refused to follow the Soviet Union's lead.

Some of my favourite quotes:

And our small planet, at this moment here, we face a critical branch-point in history. What we do with our world right now will propagate down through the centuries and powerfully affect the destiny of our descendants. It is well within our power to destroy our civilization, and perhaps our species as well. If we capitulate to superstition, or greed, or stupidity, we can plunge our world into a darkness deeper than the time between the collapse of classical civilization and the Italian Renaissance. But we are also capable of using our compassion and our intelligence, our technology and our wealth, to make an abundant and meaningful life for every inhabitant of this planet, to enhance enormously our understanding of the universe and to carry us to the stars.

But up there in the cosmos, an inescapable perspective awaits. National boundaries are not evident when we view the Earth from space. Fanatic ethnic or religious or national identifications are a little difficult to support when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars.

Human history can be viewed as a slowly dawning awareness that we are members of a larger group. Initially our loyalties were to ourselves and our immediate family, next, to bands of wandering hunter-gatherers, then to tribes, small settlements, city-states, nations. We have broadened the circle of those we love. We have now organized what are modestly described as super-powers, which include groups of people from divergent ethnic and cultural backgrounds working in some sense together — surely a humanizing and character building experience. If we are to survive, our loyalties must be broadened further, to include the whole human community, the entire planet Earth. Many of those who run the nations will find this idea unpleasant. They will fear the loss of power. We will hear much about treason and disloyalty. Rich nation-states will have to share their wealth with poor ones. But the choice, as H. G. Wells once said in a different context, is clearly the universe or nothing.

Carl Sagan also worked on the famous Pioneer plaque.

Not many people can say they've produced something that will outlive all life on Earth, the Earth itself, the Sun and the rest of the Solar System.

As sickening as this sounds in some ways I'm glad Carl Sagan isn't alive today to see how backward things have gone in recent years, how disappointed would he be? Religious extremism on the rise in both the West and the Middle East. The United States is developing even more nuclear weapons, and just yesterday announced it would consider enlarging its armed forces even more.

Carl Sagan often used the collapse of classical civilisation to underline the dangers we face in this one, only amplified many times over, the same technology we can use to feed and provide a meaningful existence for everyone on Earth can also be used to destroy us.

Rosa Luxembourg used the term "socialism or barbarism" to describe the choice humanity faces, we can either throw away all the old crap, nationalism, religious extremism, chauvinism, greed and stupidity or civilisation will collapse once again.

Carl Sagan, half a century later, said it was more a choice between life and death.

I choose life.