Saturn is almost a billion miles away from Earth, but now we know more about this planet than we know about the bottom of the oceans on Earth. On Wednesday, October 15, 1997, a Titan IVB launch vehicle with a Centaur high-energy upper stage lifted the Cassini spacecraft into Earth orbit and then sent it on the first leg of its 7-year journey to Saturn. The space probe arrived on June 30, 2004 when it entered orbit around Saturn to begin the first in-depth, up-close study of the ringed planet and its domain. NASA's robotic spacecraft carries with it 12 instruments designed to take precise measurements of Saturn and its surroundings, including Titan, other icy moons, and the rings, as well as the magnetic environment.
As expected, the Saturn System has provided an incredible wealth of opportunities for exploration and discovery. Some of those images unveil overwhelming beauty. Others show tricks of light and seemingly magical oddities. Some reveal events from the distant past that have been preserved for eons, while other views depict processes that are changing now.
There was an initial four-year tour of the Saturn system, then a two-year extended mission called the Cassini Equinox Mission, and now a second extended mission called the Cassini Solstice Mission that will continue until 2017. The schedule calls for an additional 155 orbits around the planet, 54 flybys of Titan and 11 flybys of the icy moon Enceladus.
Here are a few of the thousands of photographs that have been hand-picked by the mission scientists.
1. With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings. This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006
2. The best view of Saturn's rings is obtained by taking a photograph of the ultraviolet wavelengths. The image indicates there is more ice toward the outer part of the rings, than in the inner part, hinting at the origins of the rings and their evolution.
3. This image of Saturn's moon Enceladus back lit by the sun shows the fountain-like spray erupting from the south polar region. The greatly enhanced and colorized image shows discrete plumes of a variety of apparent sizes.
4. Few sights in the solar system are more strikingly beautiful than softly hued Saturn embraced by the shadows of its stately rings. The color variations on the planet's surface is thought to be due to differences in temperature. Despite Cassini's revelations, Saturn remains a world of mystery.
5. This image shows in superb detail the region in Saturn's rings known as the Encke Gap. It was taken by the narrow angle camera.
6. This image was taken by the European Space Agency's Huygens probe during its successful landing on the moon, Titan. The two rock-like objects just below the middle of the image are about 15 centimeters (6 inches) and 4 centimeters (1.5 inches) The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. There is also evidence of erosion indicating possible fluvial activity.
7. This is the first image ever captured of the entire auroral oval at Saturn's south pole. This light emission is similar to the Northern Lights on Earth. As on Earth, Saturn's aurora lights respond rapidly to changes in solar wind.
8. This is a terrific image of the small moon, Phoebe created by combining six high resolution photographs. This moon was discovered by William Henry Pickering in 1899. Phoebe is roughly spherical and has a diameter of 220 kilometres (140 mi), which is equal to about one-fifteenth of the diameter of Earth's Moon. Phoebe rotates on its axis every nine hours and it completes a full orbit around Saturn in about 18 months. Its surface temperature is 75 K (-198°C).
9. Flying over the unlit side of Saturn's rings, the Cassini spacecraft captures Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green, while the planet's shadow casts a wide net on the rings. This striking false-color mosaic was created from 25 images taken by Cassini's visual and infrared mapping spectrometer over a period of 13 hours. The visual and infrared mapping spectrometer acquires data simultaneously at 352 different wavelengths. The spacecraft was 6.3 million kilometers (4 million miles) from Saturn when it captured this image.
10. Is this a close up of agate banding? No, it is a close up of some of Saturn's rings. This false color image was captured by using the space probe's ultraviolet imaging spectrograph when Cassini was 6.3 million kilometers (4 million miles) from Saturn.
11. This image shows the surface of Saturn's moon, Enceladus. The enhanced color view is largely of the southern hemisphere .
12. This image of the northern polar region of Saturn shows both the aurora and underlying atmosphere, seen at two different wavelengths of infrared light. Energetic solar particles crashing into the upper atmosphere cause the aurora.
13. The existence of oceans or lakes of liquid methane on Saturn's moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it has not been possible to confirm their presence until now. Radar imaging data from the flyby provides definitive proof. This image gives a taste of what Cassini saw. Intensity in this colorized image is proportional to how much radar brightness was returned. The colors are not a representation of what the human eye would see.
14. This false-color composite image shows Saturn's rings and southern hemisphere. The composite image was made from 65 individual observations by Cassini's visual and infrared mapping spectrometer in the near-infrared portion of the light spectrum. Each photograph had a six minute exposure time.
15. This image shows four of Saturn's moons with a sliver of the rings. From left to right are Epimetheus (113 kilometers/ 70 miles across), Janus (179 kilometers/111 miles across), Prometheus (86 kilometers/ 53 miles across) and Atlas (30 kilometers/19 miles across).
The images and information are from the web site http://saturn.jpl.nasa.gov/index.cfm.
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