Galaxies in a Grain of Sand

UntitledTake a grain of sand and hold it up at the sky at arm’s length. That grain of sand covers a patch of sky equivalent to that captured by the spectacular new image from the NASA James Webb Space Telescope (JWST), the six-metre-diameter eye in the sky now settling in to its spot somewhere in deep space. The grain-of-sand image, attributed to NASA Administrator Bill Nelson, is the item which, for me, stood out amid the splurge of coverage.  For a start, it cannot help but evoke the poem Auguries of Innocence, by William Blake, which starts:

To see a World in a Grain of Sand
And a Heaven in a Wild Flower
Hold Infinity in the palm of your hand
And Eternity in an hour

… which is both apposite and ironic. Apposite, because the image is calculated to inspire a childlike wonder and awe at the Universe in which we live; ironic, given the arguably anti-scientific message of the poem. It has been through the efforts of thousands of scientists and engineers over decades that the wonder and awe has been made possible. I have liberated borrowed the image here, to show what a grain-of-sand-at-arm’s-length covers.
main_image_deep_field_smacs0723-5mbThe bright pointy thing is a foreground star. Everything else is a distant galaxy, each one on its own an island universe comprising billions of stars. Some of the galaxies are in a cluster called SMACS 0723 which, because it is so far away, and light travels at a fast but finite speed, is as it was 4.6 billion years ago — about the same time that our Solar System formed. But wait, there’s more. The reddish arcs clustered round the centre are galaxies that are even more distant, their images magnified and distorted by the gravitational field of SMAC 0723 in front of it, a phenomenon called gravitational lensing. These galaxies may be as old as 13 billion years – almost as old as the Universe itself.

Now, you might think that this particular grain of sand covers something special – but it does not. It is a tiny patch in a southern constellation called Volans. Even to its friends, this is an especially boring patch of the night sky. None of its stars is brighter than third magnitude, and the deep-sky objects in its borders are too faint for all but the most ardent telescopists to observe. The implication is clear — you could choose any tiny patch of night sky — any at all — and find within each a richness of galaxies, to any depth you please, each one home to billions of stars, and, presumably, billions of planets, and — who knows? — billions of entities holding up grains of sand in manipulatory tentacles and gasping at the scale of the Universe and their insignificance within it. But, hey, billions trillions schmillions. Powers of ten are of such magnitude that they tend to stupefy rather than edify. It’s that grain-of-sand image that sparks that visceral sense of wonder.

About Henry Gee

Henry Gee is an author, editor and recovering palaeontologist, who lives in Cromer, Norfolk, England, with his family and numerous pets, inasmuch as which the contents of this blog and any comments therein do not reflect the opinions of anyone but myself, as they don't know where they've been.
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