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Last Updated: Wednesday, 10 September, 2003, 10:28 GMT 11:28 UK
Colourful Saturn in close-up
By Dr David Whitehouse
BBC News Online science editor

This is Saturn, seen by the Hubble Space Telescope in different coloured light, when the planet's rings were on display during their rare maximum tilt of 26 degrees towards the Earth.

Saturn seen in ultraviolet, optical and infrared light
Saturn seen in ultraviolet, optical and infrared light
Over its 29.5 year-orbit Saturn and its ring system experience seasonal tilts away from and towards the Sun, in much the same way Earth does.

It means that about every 30 years, astronomers get their best view of Saturn's South Pole and the southern side of its rings.

The most recent best time was between March and April 2003, and researchers took full advantage obtaining some of the best images ever.

Layers and colours

Hubble's Wide Field Planetary Camera 2 used 30 filters that spanned a range of wavelengths, from ultraviolet, through the visible to the infrared region of the spectrum.

Saturn shows its rings
Bands of clouds at different heights and temperatures
"The set of 30 selected filters may be the best spectral coverage of Saturn observations ever obtained," says Erich Karkoschka of the University of Arizona.

Various wavelengths of light allows researchers to see into Saturn's atmosphere.

They can do this because particles in the planet's atmosphere reflect different wavelengths of light in different ways, causing some bands of gas in the atmosphere to stand out, while others will be dark or dull.

By examining the hazes and clouds seen in these multi-spectral images, researchers can learn about the dynamics of Saturn's atmosphere and gain insight into the structure and gaseous composition of Saturn's clouds.

Saturn shows its rings
The rings are never displayed better
For example, smaller aerosols are visible only in the ultraviolet, because they do not scatter or absorb visible or infrared light, which have longer wavelengths.

At certain visible and infrared wavelengths, light absorption by methane gas blocks all but the uppermost layers of Saturn's atmosphere, which helps researchers discern clouds at different altitudes.




SEE ALSO:
Saturn's winds decrease
05 Jun 03  |  Science/Nature
Mission zooms in on Saturn
04 Nov 02  |  Science/Nature
Colour clue in Saturn's rings
08 Jun 01  |  Science/Nature


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