EMBARGOED FOR 9 a The Hubble Space Telescope has taken some of the best pictures ever of Saturn. The images show the planet's rings at full tilt during a setup that won't be repeated for many years.
Saturn's rotational axis is tilted, just like Earth and the other planets. Sometimes from Earth the rings of Saturn, a mix of dust and ice chunks that orbit the planet around its equator, are seen edge-on and barely visible.
But at times during Saturn's 29.5-year orbit, the rings open up to a maximum angle of 27 degrees. From its Earth-orbiting vangagepoint, Hubble was instructed to take advantage of just such a view on March 7. The pictures were released this morning.
The new view shows Saturn's south pole and the underside of the rings, the planet's most striking feature. Scientists speculate that Earth may once have been a ringed planet, too, the result of a collision with a large space rock.
Hubble studied Saturn in detail by gathering not just one image, but three, taken with various camera filters and in several wavelengths of light.
"The set of 30 selected filters may be the best spectral coverage of Saturn observations ever obtained," said planetary researcher Erich Karkoschka of the University of Arizona.
For centuries, observers have noticed the shadow Saturn casts onto its rings. It always appeared featureless and colorless. The new images reveal that the outermost part of the shadow is orange, Karkoschka said, similar to the color of the Moon during a deep total lunar eclipse.
Saturn's tilt produces seasons on the giant gas planet, for the same reason Earth has seasons.
When Saturn's north pole leans toward the Sun, during half its orbit, spring turns to summer in the northern hemisphere, then fall ensues. During the other half of the orbit, the north pole leans away from the Sun and the southern hemisphere is the beneficiary of more direct sunlight.
Separate Hubble observations released in June showed that Saturn's top winds had decreased by 40 percent over the past two decades, to 621 mph (1,000 kilometers per hour). Astronomers were surprised to learn that a planet so far from the Sun could undergo such significant seasonal change.
Researchers will use the new images to study Saturn's atmosphere further. Small particles reflect different wavelengths of light depending on their composition. The result are the colorful bands of gas seen in the new pictures. Only by combining images made in different wavelengths, however, can scientists get a true picture of the atmosphere's chemical composition, cloud formations and dynamics.
More will soon be learned. NASA's Cassini spacecraft is en route to Saturn and will arrive next year. The robot will drop a probe onto Saturn's largest moon, Titan.
Now is a good time for casual skywatchers to see Saturn. The ringed beauty rises just before 2 a.m. in the east-northeastern sky and is high in the East by dawn. A small telescope won't give you Hubble's view, but it will reveal the planet's rings.
The ring system is about 170,000 miles wide (274,000 kilometers) but only about 30 feet (10 meters) thick. Astronomers suspect they are the remnants of a shattered object, but their exact origin is a mystery.
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