In a sense, human flesh is made of stardust.
Every atom in the human body, excluding only the primordial hydrogen atoms, was fashioned in stars that formed, grew old and exploded most violently before the Sun and the Earth came into being. The explosions scattered the heavy elements as a fine dust through space. By the time it made the Sun, the primordial gas of the Milky Way was sufficiently enriched with heavier elements for rocky planets like the Earth to form. And from the rocks atoms escaped for eventual incorporation in living things: carbon, nitrogen, oxygen, phosphorus and sulphur for all living tissue; calcium for bones and teeth; sodium and potassium for the workings of nerves and brains; the iron colouring blood red… and so on. No other conclusion of modern research testifies more clearly to mankind’s intimate connections with the universe at large and with the cosmicforces at work among the stars.
The Key to the Universe (1977)
One of my complaints is that you've got far more scientists than ever before but the pace of discovery has not increased. Why? Because they're all busy just filling in the details of what they think is the standard story. And the youngsters, the people with different ideas have just as big a fight as ever and normally it takes decades for science to correct itself. But science does correct itself and that's the reason why science is such a glorious thing for our species.
The big discoveries raise questions that make astronomers work feverishly and argue with an agitation that verges on rudeness.
Opening words, p. 7
That we shall probably never know the whole "truth" about the universe does not really matter very much; the fun comes in trying to find out. The natural pattern of current astronomy … is provided by the cryptic unity of nature itself (belief in which is the chief act of faith of the scientist) and by questions astronomers ask today, as their predecessors have done for centuries:
Whence comes the fire of the Sun and the stars?
What is the explanation of unusual phenomena in the sky (in former days, comets and supernovae; nowadays quasars and pulsars)?
How is the universe constructed and what is our place in it ?
How did the universe begin and what is its fate (and ours)?
If we were all-seeing supermen, these might appear naive and self-centred questions: there may be more significant ones which have not even occurred to us. But the humanbrain is itself a part of nature, fanned into existence by billions of years of sunshine acting on the molecules of the Earth. It is not perfectible in the immediate future, even if biologists should wish to alter the brain — which is a questionable ambition. What men make of the universe at large is a product of what they can see of it and of their own human nature.
But, when tales of the cosmos are told, this period of ours may always be recalled as that in which men first came to realise what a violent universe we inhabit.