When The Planets was completed in 1916, little was known about the physical nature of the worlds represented musically by Gustav Holst, and he didn’t care. His focus was on the planets as metaphors for different facets of the psyche; War, Peace, Jollity, Old Age, Messenger, Magician and Mystic. Indeed, Holst wrote parts of the work as stand-alone pieces and co-opted them later.
Today we have visited all the planets and our discoveries have replaced their ancient astrological characters. At first sight, this new knowledge might appear to jar with Holst’s work, but this would be a superficial conclusion to draw. The planets have histories far richer than Holst could have imagined and reality delivers more powerful metaphors than myth. Set against what we now know, Holst’s work catalyses new ideas and generates powerful intellectual challenges which enrich and inform important debates in progress today, as art with depth can and perhaps must do.
Music from the past is not a fossil in the same way that Aristotle, Shakespeare and Newton do not belong in airless cases; music emerges from the ferment of ideas and contributes to the vitality of the brew; as such it is a transcendent ingredient of intellectual life.
Perhaps the most vivid example is Venus; Bringer of Peace, the evening star, brightest of worlds. As late as the early 1960s, reputable astronomers imagined a tropical paradise beneath her ever-present blanket of clouds, but Russian and American spacecraft dashed these hopes towards the end of the decade. Temperatures at the planet’s surface are in excess of 460C, and the rocks are crushed by atmospheric pressure a hundred times that of Earth and bathed in sulphuric acid rain. Venus is a vision of hell.
Yet Venus may once have been temperate, life-supporting perhaps, with rivers and oceans and blue skies. As late as two billion years ago, when life was well established on Earth, a runaway greenhouse effect boiled the oceans away and thickened the atmosphere, destroying any life that may have been present. Listen to Holst’s Venus with this history in mind, and the piece becomes a requiem for a failed planet, a paean to transience. The laws of nature allow for the spontaneous emergence of beauty but only as an intermediate destination between creation and decay. A reminder that planets, just as human beings, were once born and will one day die, and it is this fragility and unavoidable transience that makes them precious.
Mars, Bringer of War, blood red in the imagination, has always been a mirror for our nightmares and dreams. Written before the first world war, Holst’s motivation was likely a critique of industrial capitalism; a prophetic work which found new resonance and power when set against the images of mechanised warfare that dominated the decades following its composition.
Before the flyby of the Mariner 4 spacecraft in July 1965, it was possible to imagine Mars as a living world; a new Eden perhaps, or home to the envious eyes of HG Wells’ invaders. The photographs from Mariner revealed a very different Mars; a desiccated world not dissimilar to our Moon. This came as a shock, and prompted President Lyndon Johnson into a rare and valuable moment of existential reflection – for a politician. “It may be, it may just be that life as we know it, with its humanity, is more unique than many have thought.” The hesitation in the first few words is revealing. Here is Mars as a symbol of our cosmic isolation. It is as though, deep or perhaps not so deep in the subconscious, the 1960s power brokers all the way up to the President suddenly understood that the Earth is far more fragile and precious than a dispassionate analysis of their cold war brinkmanship might suggest. Or perhaps the perspective delivered by exploration is always shocking. Apollo 8’s Earthrise, the photograph that delivered such a positive end to a troubled 1968 by setting the blue Earth against the grey Moon was three years away, but red Mars provided a foretaste.
More recent missions to Mars have revealed a more nuanced story. Mars was certainly warmer and wetter 3.5 billion years ago as life was taking hold on Earth. This means that life may have begun on the red planet, and may still exist in the sub-surface reservoirs of water we know to exist today. The discovery of a second genesis in our solar system would have profound philosophical, scientific and cultural consequences, because it would mean there is a sense of inevitability about the origin of life. And that would mean that the universe is most likely teeming with life: that we are not alone.
A planet with a history like Mars may also play a defining role in our future. Mars is rich in resources; all the things needed to support a civilisation. Even if there are no Martians today, there will be soon: The Martians will be us. Mars is the only planet we could ever hope to visit. The others are far too hostile.
Mars is not Bringer of War; it is Bringer of Hope. Is it too much to ask to listen to Holst’s Mars and forget the deeply ingrained 20th-century symbolism? To engage in a 21st-century argument with the composer that, having survived the barbarism, our technology and rockets are freed to deliver perspective on our cosmic isolation and provide a bridge to a future when humanity is no longer confined to a single world? “The Earth is the cradle of mankind,” wrote the great Russian rocket scientist Konstantin Tsiolkovsky, “but one cannot stay in the cradle forever.”
The Planets ends with Neptune the Mystic. In contrast to Mars and Venus, we need not work so hard to find meaning in the synthesis between music and ideas. There is a single photograph taken by Voyager 2 in 1989 that enhances the music more than words. It is my personal favourite from the long and spectacular history of space exploration. This is an image from the frozen outpost of the solar system over four billion kilometres from Earth. Crescent Neptune and her moon Triton, a world of ice 230 degrees below zero orbiting a blue planet of storms, yet, incredibly, geologically active with cryovolcanoes sprinkling nitrogen snow over the surface.
Two worlds that remained unseen for 4.5 billion years after their formation until a tiny emissary from Earth passed by on its way into interstellar space. A twilight gateway to the stars that lingers in the imagination as the choir fades away.
• Professor Brian Cox joins the BBC Symphony Orchestra for Holst’s The Planets at the Barbican, London on 29 September, broadcast live on Radio 3 and available on TV as part of ‘Our Classical Century’ next year.