Saturn Planet

Saturn is the sixth planet from the Sun and is the second largest in the solar system with an equatorial diameter of 119,300 kilometers (74,130 miles). Much of what is known about the planet is due to the Voyager explorations in 1980-81.

Saturn is visibly flattened at the poles, a result of the very fast rotation of the planet on its axis. Its day is 10 hours, 39 minutes long, and it takes 29.5 Earth years to revolve about the Sun. The atmoshere is primarily composed of hydrogen with small amounts of helium and methane.

Saturn is the only planet less dense than water (about 30 percent less). In the unlikely event that a large enough ocean could be found, Saturn's hazy yellow hue is marked by broad atmospheric banding similiar to, but fainter than, that found on Jupiter.

The wind blows at high speeds on Saturn. Near the equator, it reaches velocities of 500 meters a second (1,100 miles an hour). The wind blows mostly in an easterly direction. The strongest winds are found near equator and velocity falls off uniformly at higher latitudes. At latitudes greater than 35 degrees, winds alternate east and west as latitude increases.

Saturn's ring system makes the planet one of the most beautiful objects in the solar system. The rings are split into a number of different parts, which include the bright A and B rings and a fainter C ring.

The ring system has various gaps. The most notable gap is the Cassini [kah-SEE-nee] Division, which separates the A and B rings. Giovanni Cassini discovered this division in 1675. The Encke [EN-kee] Division, which splits the A Ring, is named after Johann Encke, who discovered it in 1837.

Space probes have shown that the main rings are really made up of a large number of narrow ringlets. The orignin of the rings is obscure. It is thought that the rings may have been formed from larger moons that were shattered by impacts of comets and meteoroids.

The ring composition is not known for certain, but the rings do show a significant amount of water. They may be composed of icebergs and/or snowballs from a few centimeters to a few meters in size.

Much of the elobarate structure of some of the rings is due to the gravitional effects of nearby satellites. This phenomenon is demonstrated by the relationship between the F-ring and two small moons that sheperd the ring material.


Source: www.solarviews.com

Planet-Hunting Kepler Telescope Lifts Its Lid

The hunt is on. The Kepler spacecraft opened to the universe this week and is getting set to search for Earth-size planets around distant stars. Perhaps we'll find a home for E.T. I'm simply thrilled that this critical next step went off without a hitch.

On Tuesday evening, the Kepler spacecraft blew its lid. Well, actually it was a lot calmer than that; the cover was ejected in a carefully engineering maneuver.

At 7:13:36 PM, engineers at Kepler's mission operations center at the Laboratory for Atmospheric and Space Physics (LASP), Boulder, Colo., sent commands to pass an electrical current through a "burn wire" to break the wire and release a latch holding the cover closed. The spring-loaded cover swung open on a fly-away hinge, and then drifted away from the spacecraft.

The teloscope's oval-shaped dust cover, measuring 1.7 meters by 1.3 meters (670 inches by inches), protected the photometer from contamination before and after launch. The dust cover also blocked stray light from entering the telescope during launch-v light that could have damaged its sensitive detectors.

In addition, the cover was important for calibrating the photometer. Images taken in the dark helped characterize noise coming from the instrument's electronics, and this noise will later be removed from the actual science data.

"The cover released and flew away exactly as we designed it to do," said Kepler Project Manager James Fanson of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This is a critical step toward answering a question that has come down to us across 100 generations of human history-are there other planets like Earth, or are we alone in the galaxy?"

"Now the photemeter can see the stars and will soon start the task of detecting the planets," said Kepler's Science Principal investigator William Borucki at NASA's Ames Research Center, Moffett Field, Calif. "We have thoroughly measured the background noise so that our photometer can detect minute changes in a star's brightness caused by planet."

Deputy Principal Investigator, Dr. David Koch, watched the cover ejection from NASA Ames Research Center, celebrating with the kepler Science Operations Center team.

"Besides launch, this was the most critical event for the Kepler spacecraft, and everything went as expected," he said. "The spacecraft settled after the ejection, and the star trackers were rock solid. The first images have been taken, and we look forward to reviewing those shortly. It was a truly exciting event."

With the cover off, starlight is entering the photemeter and being imaged onto its focal plane. Engineers will continue calibrating the instrument using images of stars for another several weeks, after which science observations will begin.


By Edna DeVore, SETI Institute, www.space.com