All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star stuff.
We are made of starstuff.
We are star stuff which has taken its destiny into its own hands.
We are made out of stardust. The iron in the hemoglobin molecules in the blood in your right hand came from a star that blew up 8 billion years ago. The iron in your left hand came from another star.
Since the universe must contain millions of appropriate planets, consciousness in some form - but not with the paired eyes and limbs, and the brain built of neurons in the only example we know - may evolve frequently. But if only one origin of life in a million ever leads to consciousness, then Martian bacteria most emphatically do not imply Little Green Men.
If you're sending a message to extraterrestrials, what you want to send is what's special about us and our planet - what is unusual. Now, that's not basic chemistry or mineralogy; it's pretty much the cultural stuff and the consequences of evolution.
There are millions of stars out there. It is difficult to think that life does not exist in any one of them.
It's important that we attempt to extend life beyond Earth now. It is the first time in the four billion-year history of Earth that it's been possible, and that window could be open for a long time - hopefully it is - or it could be open for a short time. We should err on the side of caution and do something now.
The more we know about life out there the easier it will be to improve life down here.
About the only things that are unique to Earth are our biota and our culture. If aliens ever come here, they'd most likely be either biologists or music fans. Neither one has much reason to antagonize our armed forces.
We are the representatives of the cosmos; we are an example of what hydrogen atoms can do, given 15 billion years of cosmic evolution.
While NASA talks about 'Are we alone?' as a number one question, they are putting zero money into searching for intelligent life. There's a big disconnect there.
It is quite moving to hold a piece of Mars in your hands and to reflect on its incredible interplanetary journey, and the science that gives confidence as to the origin of this unusual rock.
The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us.
I am very excited to be supporting one of the world's most visionary efforts to seek basic answers to some of the fundamental question about our universe and what other civilisations may exist elsewhere.
The origin of life is one of the great outstanding mysteries of science.
To me, it's the kind of interesting question the human race should be investing in. Is there intelligent life out there? Are there other beings out there?
One of the jovian moons, Europa, is coated with twice as much liquid water as is sloshing around our planet.
Might it be the discovery of a distant civilization and our common cosmic origins that finally drives home the message of the bond among all humans. Whether we're born in San Francisco or Sudan or close to the heart of the Milky Way Galaxy, we are the products of a billion-year lineage of wandering stardust. We, all of us, are what happens when a primordial mixture of hydrogen and helium evolves for so long that it begins to ask where it came from.
The best way to study Mars is with two hands, eyes and ears of a geologist, first at a moon orbiting Mars... and then on the surface.
The Eerie Silence: are we alone in the universe?
Stars, of course, are too hot to support life, so wherever life might exist in the universe, it has to be on planets or moons that are warmed, but not incinerated, by the stars they travel around.
It's presumptuous for us to think we are the only beings in the cosmos.
I believe alien life is quite common in the universe, although intelligent life is less so. Some say it has yet to appear on planet Earth.
I've always thought that we, as human beings, would be naive and arrogant to pretend that we're the only life form in the galaxy.
