Art - Judith Palmer on the unworldly beauty of images beamed from the Hubble Space Telescope
All photography represents a moment frozen in time, but just how far into the past can photography take us? To 1826, surely, and those eight tranquil hours of Burgundian farm life, observed by Joseph Nicephore Niepce from a high casement window, and slowly fixed on a bitumen-coated pewter plate as the earliest surviving heliograph. But not so.
On 2 April this year, Nasa released a photograph from the Hubble Space Telescope of a supernova blast illuminating the most distant part of the universe ever seen. A reddish blip in the super-darkness captured the very moment that a dying star went ker-bang in a cataclysmic stellar explosion.
The event was recorded by Hubble back in 1997: the sudden appearance of a tiny speckle of light, way back in the deep field behind Ursa Major, that had never been there before. It took a further three and a half years before an astronomer analysed the picture and worked out the significance of what he had seen. Perhaps three and a half years seems an unreasonable time delay before reporting this important astronomical discovery. The furthest flash of light in the cosmos had, after all, been racing along at 186,291 miles a second to bring news of itself to planet earth. Even at that pace, intergalactic news travels slowly. For what Hubble had photographed was in fact an event that had occurred ten billion years previously, before our own solar system was even born.
"Hubble's Universe", a magnificent new exhibition of large-scale colour photographs at London's Blue Gallery, displays "recent images from the Hubble Space Telescope". Recent but ancient. Astronomical photography is rather like forensic archaeology. By the time we arrive at the scene of the crime, the drama has long since unfolded. We are watching ghosts.
Looking into the marbled vortex of "Spiral Galaxy NGC 4603" is to look back in time 108 million light years. This whirlpool of pulsating stars spins like an elegant creamy Catherine wheel, arms of light trailing curvaceously through the dark. Some of her stars are seen as young, bright blue clusters; others are red giants, already in their death throes. Six million light years longer ago, another photo captures two more spiral galaxies, set on a swirly collision course, coalescing as they move side by side and forming the shape of a pair of Dame Edna spectacles.
Hubble's embarrassing early myopia now corrected, the images are spectacularly crisp. The "Ant Nebula", between a mere 3,000 and 6,000 light years away, looks alarmingly like a shucked-off bug-skin. Its twin bubbles of gelatinous liquescence froth out into the shape of an egg-timer with a pinky-violet twinkle at its waist. "The Eskimo Nebula", first identified by William Herschel in 1787, does indeed resemble an opalescent, bear-like face, looming out of an amber ring of fur. It is rather like one of those hologram heads of superbeings that float outside the flight-deck of the Starship Enterprise. There sure are some weird-looking objects out there.
The photographs from the Hubble Space Telescope (HST) do not portray images as they would appear to the human eye, however. The only wavelengths that our eyes can detect are the rainbow of colours in the visible spectrum. We cannot see radio waves, microwaves, infra-red, ultraviolet, X-rays, gravity waves or gamma-rays, although they are all out there, fizzing and glowing in beautiful, complex patterns.
Floating 380 miles above us, just out of the earth's atmosphere (which obscures and distorts light) the HST Wide Field Planetary Camera takes multiple exposures, using a range of filters. The images all come back in black and white; but astronomers reassemble the different layers, assigning colours at random to each different wavelength, like you would with a painting-by-numbers kit, to highlight whichever faint structure they wish to focus on.
Just as every Victorian photographic studio had a resident watercolourist to hand-tint rosy cheeks and gild fob watches on to the monochrome portraits, the Space Telescope Science Institute in Baltimore, Maryland, has a seven-strong team of astronomers, known as the Hubble Space Heritage Team, who select the most visually intriguing objects recorded by HST and convert them into luscious and subtly selected false colour.
The huge globe of Jupiter shakes off its usual solid brown to appear here in new hues of ethereal ivory and palest cool blue. Its orbiting moon Io dances her dark shadow across Jupiter's delicate surface pattern of bands and spots. Taken in violet and ultraviolet, the picture emphasises the planet's rippling wind currents. Nearby, Mars is taken in "true colour", which allows the red planet to emerge almost earth-like in turquoise and orange with wispy white morning clouds.
A couple of non-Hubble pictures creep into the exhibition, too: the iconic picture from Apollo 11 of earth-rise over the moon; and yellow Saturn with its tilting hoopla rings, shot by Voyager in ultraviolet and infra-red as it peers through its hazy methane smog. Also, from the Solar and Heliospheric Observatory, an awesome picture of the sun, bubbling like a big latticed ball of molten toffee, a vast solar flare blow-torching out from its surface.
Like medieval map-makers, we attempt to chart what we cannot see and only partly understand. Here be dragons. There be red dwarves.
Judith Palmer is a writer and broadcaster
"Hubble's Universe" is at the Blue Gallery (020 7490 3833), London EC1, until 2 June
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