Within art's orbit

A Hubble retrospective - the skies as you've never seen them before. By Charles Arthur

Rather as Garry Kasparov found a worthy, if nonsentient chess opponent in the IBM computer Deep Blue, the wave of young artists rejecting oil painting in favour of digital manipulation have some serious competition from the orbiting Hubble Space Telescope. Today an exhibition opens at the Blue Gallery in London, showing a number of HST images blown up to more than a square metre. The attraction for gallery visitors lies just as much in their abstract form as their scientific content.

The collection of 13 images has been chosen from the hundreds taken by the HST. There is also a parallel exhibition of other HST images running at the Science Museum, in South Kensington, so that those who wish to take their fill of the abstract nature of the universe will find plenty to occupy them. As Arthur C Clarke, the famous British science-fiction writer, comments in a note to accompany the gallery exhibition, "First look and enjoy; later think about the implications."

But those unable or unwilling to travel to London will still find many of the images reproduced in high quality, with explanatory text in the book Universe in Focus: the story of the Hubble Telescope by Stuart Clark. This includes a history of the HST, as well as useful comparisons of images taken from the ground, and before and after its repair in December 1993. Hubble is now working near the theoretical limits of its instruments: we are seeing the universe, both near and distant, in more detail than ever before. And if any scientist is tempted to think that it lowers such work to display it as "art", it's worth reflecting that during the month that it lasts, the Blue Gallery's exhibition expects to draw 10 times more people than usual every dayn

The Blue Gallery is at 93 Walton St, London SW3. The exhibition runs until 19 July, with a parallel exhibition at the Science Museum.

"Universe in Focus: the story of the Hubble Telescope" by Stuart Clark is priced pounds 16.99 from Cassell, ISBN 0-304-34945-3.

The methane atmosphere of Neptune (left) absorbs red and infrared light, leading it to appear blue in this pair of images showing the weather on its opposite hemispheres. Clouds raised above most of the methane appear white, while the very highest clouds are yellow-red (the top of the right image). The green belt towards the south shows an area where the atmosphere absorbs blue light. The two images were taken over one rotation of Neptune, lasting just over 16 hours.

All photographs: Nasa

A sequence of 10 false-colour images of Saturn and its rings (right- hand page) shows a number of the gas giant's small moons. The images are paired, left and right. Note that a pair of stars passes behind the rings during the sequence, becoming visible on their own in the ninth frame. In the rest of the sequence, the moons Dione, Pandora, Prometheus, Mimas, Rhea and Epimetheus all emerge from behind the ring before disappearing again during the orbit. The pictures were taken by Hubble as it orbited the Earth, taking one pair every 97 minutes.

False colours can be useful. The rings around Uranus are not really white, but as black as charcoal. This infrared image, viewing the planet from its south pole, shows three layers of Uranus's atmosphere, composed of hydrogen and methane. The effect of the imaging is like looking at the edge of a soap bubble. The deepest layer is the blue, near the top, showing a clear atmosphere; the next layer is the yellow one, a methane- hydrogen haze. The pink ring is high-altitude haze around the planet's equator.

The Hubble Deep Field is a look as far away as seems possible: to the visible horizon of the universe. A number of the distant galaxies here are about 13 billion light years away, and so faint that they are nearly four billion times dimmer than can be seen with human vision. This true-colour image was built up from 276 separate exposures over 10 days. Its value to astronomers is in the clues it contains about the way that galaxies and stars form.