* Astronomy

Members Login
Post Info
TOPIC: Saturn


L

Posts: 131433
Date:
RE: Saturn
Permalink  
 


From Saturn orbit, the Cassini spacecraft provides a perspective on the ringed planet that is never seen from Earth.


Expand (32kb, 1024 x 1024)

In our skies, Saturn's disk is always nearly fully illuminated by the sun. From this vantage point -- nearly in the ring plane, with the sun over to the right -- the Cassini spacecraft can see both lit and dark hemispheres, with the shadow of the rings on the Northern Hemisphere.

Saturn's low density and fast rotation cause its shape to deviate from spherical to a pronounced oblateness, very apparent here.

The image was taken using the Cassini spacecraft wide-angle camera and a filter sensitive to wavelengths of infrared light centred at 728 nanometres. The image was acquired on Sept. 30, 2005, at a distance of approximately 2.4 million kilometres from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 79 degrees. The mage scale is 139 kilometres per pixel.

__________________


L

Posts: 131433
Date:
RE: Saturn clouds
Permalink  
 


This is a collection of the most detailed images of deep-level clouds obtained by the visual and infrared mapping spectrometer onboard the Cassini spacecraft.
Images were obtained at 5.1 micron wavelength, inverted photographically to show clouds as bright.
Donut-shaped clouds are seen near the North Pole (upper panel).


Expand (348kb, 2800 x 2196)
The images were acquired during three passes by Saturn between February and July, 2005.
The top image was acquired on Feb. 17, 2005, from a distance of 683,000 kilometres.
The middle image was acquired on March 8, 2005, from 725,000 kilometres altitude.
The bottom image was acquired on July 12, 2003, from a distance of 1.1 million kilometres.



A planetary wave pattern dominates the cloud structures just south of the equator (upper part of middle panel), with many swirls of clouds connected to discrete cloud cells. The southern hemisphere is striped with numerous thin lanes of clouds throughout the southern hemisphere (bottom image, and middle part of middle image). Many thin wisps of clouds appear to be connected to discrete cloud cells.


__________________


L

Posts: 131433
Date:
RE: Saturn rings
Permalink  
 


Data from the NASA/ESA/ASI Cassini spacecraft indicate that Saturn's majestic ring system has its own atmosphere - separate from that of the planet itself.

During its close fly-bys of the ring system, instruments on Cassini have been able to determine that the environment around the rings is like an atmosphere, composed principally of molecular oxygen.


Expand

This atmosphere is very similar to that of Jupiter's moons Europa and Ganymede.
The finding was made by two instruments on Cassini, both of which have European involvement: the Ion and Neutral Mass Spectrometer (INMS) has co-investigators from USA and Germany, and the Cassini Plasma Spectrometer (CAPS) instrument has co-investigators from US, Finland, Hungary, France, Norway and UK.
Saturn's rings consist largely of water ice mixed with smaller amounts of dust and rocky matter. They are extraordinarily thin: though they are 250 000 kilometres or more in diameter they are no more than 1.5 kilometres thick.
Despite their impressive appearance, there is very little material in the rings - if the rings were compressed into a single body it would be no more than 100 kilometres across.

The origin of the rings is unknown. Scientists once thought that the rings were formed at the same time as the planets, coalescing out of swirling clouds of interstellar gas 4000 million years ago. However, the rings now appear to be young, perhaps only hundreds of millions of years old.
Another theory suggests that a comet flew too close to Saturn and was broken up by tidal forces. Possibly one of Saturn's moons was struck by an asteroid smashing it to pieces that now form the rings.

Though Saturn may have had rings since it formed, the ring system is not stable and must be regenerated by ongoing processes, probably the break-up of larger satellites.
Water molecules are first driven off the ring particles by solar ultraviolet light. They are then split into hydrogen, and molecular and atomic oxygen, by photodissocation. The hydrogen gas is lost to space, the atomic oxygen and any remaining water are frozen back into the ring material due to the low temperatures, and this leaves behind a concentration of oxygen molecules.

"As water comes off the rings, it is split by sunlight; the resulting hydrogen and atomic oxygen are then lost, leaving molecular oxygen. The INMS sees the neutral oxygen gas, CAPS sees molecular oxygen ions and an ‘electron view’ of the rings. These represent the ionised products of that oxygen and some additional electrons driven off the rings by sunlight" - Dr Andrew Coates, co-investigator for CAPS, from the Mullard Space Science Laboratory (MSSL) at University College London.

Dr Coates said the ring atmosphere was probably kept in check by gravitational forces and a balance between loss of material from the ring system and a re-supply of material from the ring particles.

source

__________________


L

Posts: 131433
Date:
RE: Saturn
Permalink  
 


New images of Saturn obtained by a University of Colorado at Boulder-led team on June 21 using an instrument on the Cassini spacecraft show auroral emissions at its poles similar to Earth's Northern Lights.
Taken with the Ultraviolet Imaging Spectrograph aboard the Cassini orbiter, the two UV images, invisible to the human eye, are the first from the Cassini-Huygens mission to capture the entire "oval" of the auroral emissions at Saturn's south pole. They also show similar emissions at Saturn's north pole, according to CU-Boulder Professor Larry Esposito, principal investigator of the UVIS instrument built at CU-Boulder's Laboratory for Atmospheric and Space Physics, and Professor Wayne Pryor of Central Arizona College, a UVIS team member and former CU graduate student.



In the false-colour images, blue represents aurora emissions from hydrogen gas excited by electron bombardment, while red-orange represents reflected sunlight. The images show that the aurora lights at the polar regions respond rapidly to changes in the solar wind, said the researchers. Previous images have been taken closer to the equator, making it difficult to see the polar regions.
Major changes in the emissions inside the Saturn south-pole aurora are evident by comparing the two images, which were taken about one hour apart, they said. The brightest spot in the left aurora fades, and a bright spot appears in the middle of the aurora in the second image.
Made by slowly scanning the UVIS instrument across the planet, the images also contain more than 2,000 wavelengths of spectral information within each picture element. Researchers will use the wavelength information to study Saturn's auroras, gases, and hazes and their changing distributions.

Source

__________________


L

Posts: 131433
Date:
RE: Radio Saturn
Permalink  
 


Saturn is a source of intense radio emissions, which have been monitored by the Cassini spacecraft. The radio waves are closely related to the auroras near the poles of the planet. These auroras are similar to Earth's northern and southern lights. This is an audio file of Saturn's radio emissions.

The Cassini spacecraft began detecting these radio emissions in April 2002, when Cassini was 374 million kilometres from the planet, using the Cassini radio and plasma wave science instrument. The instrument has now provided the first high resolution observations of these emissions, showing that show an amazing array of variations in frequency and time.
In this example, it appears as though the three rising tones are launched from the more slowly varying narrowband emission near the bottom of this display. If this is the case, it represents a very complicated interaction between waves in Saturn's radio source region, but one which has also been observed at Earth.

Time on this recording has been compressed such that 13 seconds corresponds to 27 seconds. Since the frequencies of these emissions are well above the audio frequency range, we have shifted them downward by a factor of 260.

Click here to play sounds of Saturn's radio emissions, which have changes in frequency (127Kb Wave Sound).


__________________
Anonymous

Date:
RE: Saturn's ring
Permalink  
 


Saturn's ring system has its own separate atmosphere from that of the planet itself, according to data from the Cassini spacecraft.

Saturn rotates seven minutes more slowly than when probes measured its spin in the 70s and 80s - an observation experts cannot yet explain.

Details were unveiled at the British Festival of Space 2005 in Birmingham.
By making close flybys of the ring system, Cassini has been able to determine that the atmosphere around the rings is composed principally of molecular oxygen (O2).

The finding was made by two experiments on Cassini: the Ion and Neutral Mass Spectrometer (INMS) and Cassini Plasma Science (Caps) instrument.

"The INMS sees the neutral oxygen gas, Caps sees the ionised products of that oxygen and the electrons associated with it. There is an enhancement over the rings" - Professor Andrew Coates, co-investigator for the Caps instrument.

Professor Coates, from the Mullard Space Science Laboratory (MSSL) at University College London, said the atmosphere was very similar to that of Jupiter's moons Europa and Ganymede.

"As water comes off the rings, the hydrogen is lost from it, leaving the oxygen".

Saturn's rings consist largely of water ice mixed with smaller amounts of rocky matter.
Scientists admitted they were surprised by the finding that Saturn's rotation is slowing.
"The rotation seems to have slowed down by about seven minutes compared to what was inferred from the Pioneer and Voyager data, but we don't actually understand why" - Dr Michele Dougherty, principal investigator for Cassini's magnetometer instrument.

Data from the magnetometer and Cassini's Radio and Plasma Wave Science (RPWS) instrument both seem to show the slow down in Saturn's rotation.

"You would expect the rotation of the planet to slow down if its internal dynamo had stopped, but that does not seem to be the case with Saturn. If you sit down and think about it, its very difficult to come up with a scenario where the interior of the planet is slowing down. " - Dr Michele Dougherty.

The internal dynamo is the source of a planet's magnetic field and requires rotation and a fluid core. It was possible the instruments were observing "rotational regions" closer to the surface of Saturn rather than anything to do with the dynamo itself.
UK science and innovation minister Lord Sainsbury, who was at the briefing in Birmingham, praised UK scientists involved in Cassini-Huygens as the orbiter celebrated its first year in orbit around Saturn.

"The scientists and engineers in this country have played an integral role, making it the biggest British success story in space of the last 12 months" Lord Sainsbury.
Cassini performed its Saturn Orbit Insertion (SOI) on 1 July 2004 after a six-year, three billion-kilometre trek.

In December 2004, it released its piggybacked Huygens probe, which performed a successful touchdown on Saturn's moon Titan in February this year.
The mission is a co-operative mission between the US space agency Nasa, the European Space Agency (Esa) and the Italian Space Agency (Asi).

__________________


L

Posts: 131433
Date:
RE: Saturn
Permalink  
 


This image of Saturn was taken on June 29, 2005 and received on Earth June 29, 2005 by the Cassini spacecraft.


Expand

The image was taken using the CL1 and CL2 filters.

__________________


L

Posts: 131433
Date:
RE: Saturn's clouds
Permalink  
 


An up-close look at Saturn's atmosphere shows wavelike structures in the planet's constantly changing clouds.


Expand

Feathery striations in the lower right appear to be small-scale waves propagating at a higher altitude than the other cloud features.
The image was taken with the Cassini spacecraft wide-angle camera on April 14, 2005, through a filter sensitive to wavelengths of infrared light centred at 727 nanometres and at a distance of approximately 386,000 kilometres from Saturn.
The image scale is 19 kilometres per pixel.

If you’re looking for a MUI background


__________________


L

Posts: 131433
Date:
RE: Saturn
Permalink  
 


Saturn's icy moon Enceladus hovers above Saturn's exquisite rings in this colour view from Cassini.


Expand

The rings, made of nearly pure water ice, have also become somewhat contaminated by meteoritic dust during their history, which may span several hundred million years. Enceladus shares the rings' nearly pure water ice composition, but appears to have eluded dust contamination through resurfacing processes that scientists are still trying to understand. Enceladus is 505 kilometres across.

Dust affects the rings' colour, while differences in brightness are attributable to varying particle sizes and concentrations.
The images for this natural colour view were taken with the Cassini spacecraft narrow-angle camera on April 5, 2005, at a distance of approximately 2.2 million kilometres from Saturn through red, green and blue spectral filters.
The image scale is 13 kilometres per pixel.







__________________


L

Posts: 131433
Date:
Permalink  
 

The Cassini spacecraft discovered intriguing dust particles around Saturn's moon Enceladus during its February 17 flyby, and during another flyby on March 9 at an altitude of 500 kilometres. The onboard cosmic dust analyzer recorded thousands of particle hits during a period of 38 minutes.
The largest particles detected measure no more than the diameter of a human hair.

The particles might indicate the existence of a dust cloud around Enceladus, or they may have originated from Saturn's outermost ring, the E-ring.
Future encounters with Enceladus are scheduled for July 14, 2005, and March 12, 2008. The July 14 flyby was to be at an altitude of 1,000 kilometres, but the mission team now plans to lower that altitude to about 175 kilometres. This will probably be Cassini's lowest-altitude flyby of any object during its nominal four-year tour.


__________________
«First  <  18 9 10 | Page of 10  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard