Electric Saturn

Historic planetary instability and catastrophe. Evidence for electrical scarring on planets and moons. Electrical events in today's solar system. Electric Earth.

Moderators: MGmirkin, bboyer

Electric Saturn

Unread postby StefanR » Fri May 02, 2008 4:49 am

As a powerful electrical storm rages on Saturn with lightning bolts 10,000 times more powerful than those found on Earth, the Cassini spacecraft continues its five-month watch over the dramatic events.

Scientists with NASA's Cassini-Huygens mission have been tracking the visibly bright, lightning-generating storm--the longest continually observed electrical storm ever monitored by Cassini.

Saturn's electrical storms resemble terrestrial thunderstorms, but on a much larger scale. Storms on Saturn have diameters of several thousand kilometers (thousands of miles), and radio signals produced by their lightning are thousands of times more powerful than those produced by terrestrial thunderstorms.

Image
"The electrostatic radio outbursts have waxed and waned in intensity for five months now," said Georg Fischer, an associate with the radio and plasma wave science team at the University of Iowa, Iowa City. "We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn."


Cassini's radio plasma wave instrument detects the storm every time it rotates into view, which happens every 10 hours and 40 minutes, the approximate length of a Saturn day. Every few seconds the storm gives off a radio pulse lasting for about a tenth of a second, which is typical of lightning bolts and other electrical discharges. These radio waves are detected even when the storm is over the horizon as viewed from Cassini, a result of the bending of radio waves by the planet's atmosphere.

http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=837
Last edited by nick c on Fri Mar 25, 2011 10:51 am, edited 1 time in total.
Reason: Thread title changed for purpose of merging posts
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Fri May 02, 2008 4:53 am

Hissing Storm
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=3058
A bright, powerful, lightning-producing storm churns and coasts along the lane of Saturn's southern hemisphere nicknamed "Storm Alley" by scientists.
NASA's Cassini spacecraft detected this particular tempest after nearly two years during which Saturn did not appear to produce any large electrical storms of this kind. The storm appears as a bright, irregular splotch on the planet near lower right.

Lightning flashes within the persistent storm produce radio waves, called Saturn Electrostatic Discharges, which the Cassini radio and plasma wave science instrument first detected on Nov. 27, 2007. Cassini's imaging cameras then spotted the storm, taking the images used to create this color view about a week later on Dec. 6.

This electrical storm is similar in appearance and intensity to those previously monitored by Cassini. All of these powerful electrostatic producing storms appeared at about 35 degrees south latitude on Saturn. (See Storm at Night, Against the Current and The Dragon Storm for additional images of Saturn's electrical storms imaged by Cassini.)


Image
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2000
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Fri May 02, 2008 4:54 am

Image

Scientists gave the nickname "Storm Alley" to the area around 35 degrees south latitude because of the large amount of activity seen there from the beginning of the Cassini spacecraft's approach to Saturn in early 2004. The region has spawned two large and powerful storms since the Cassini spacecraft began observations.

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2047
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Fri May 02, 2008 4:59 am

Image

Saturn's atmosphere and its rings are shown here in a false color composite made from Cassini images taken in near infrared light through filters that sense different amounts of methane gas. Portions of the atmosphere with a large abundance of methane above the clouds are red, indicating clouds that are deep in the atmosphere. Grey indicates high clouds, and brown indicates clouds at intermediate altitudes. The rings are bright blue because there is no methane gas between the ring particles and the camera.

The complex feature with arms and secondary extensions just above and to the right of center is called the Dragon Storm. It lies in a region of the southern hemisphere referred to as "storm alley" by imaging scientists because of the high level of storm activity observed there by Cassini in the last year.

The Dragon Storm was a powerful source of radio emissions during July and September of 2004. The radio waves from the storm resemble the short bursts of static generated by lightning on Earth. Cassini detected the bursts only when the storm was rising over the horizon on the night side of the planet as seen from the spacecraft; the bursts stopped when the storm moved into sunlight. This on/off pattern repeated for many Saturn rotations over a period of several weeks, and it was the clock-like repeatability that indicated the storm and the radio bursts are related. Scientists have concluded that the Dragon Storm is a giant thunderstorm whose precipitation generates electricity as it does on Earth. The storm may be deriving its energy from Saturn's deep atmosphere. (???)

One mystery is why the radio bursts start while the Dragon Storm is below the horizon on the night side and end when the storm is on the day side, still in full view of the Cassini spacecraft. A possible explanation is that the lightning source lies to the east of the visible cloud, perhaps because it is deeper where the currents are eastward relative to those at cloud top levels. If this were the case, the lightning source would come up over the night side horizon and would sink down below the day side horizon before the visible cloud. This would explain the timing of the visible storm relative to the radio bursts.

The Dragon Storm is of great interest for another reason. In examining images taken of Saturn's atmosphere over many months, imaging scientists found that the Dragon Storm arose in the same part of Saturn's atmosphere that had earlier produced large bright convective storms. In other words, the Dragon Storm appears to be a long-lived storm deep in the atmosphere that periodically flares up to produce dramatic bright white plumes which subside over time. One earlier sighting, in July 2004, was also associated with strong radio bursts. And another, observed in March 2004 and captured in a movie created from images of the atmosphere (http://photojournal.jpl.nasa.gov/catalog/PIA06082 and http://photojournal.jpl.nasa.gov/catalog/PIA06083) spawned three little dark oval storms that broke off from the arms of the main storm. Two of these subsequently merged with each other; the current to the north carried the third one off to the west, and Cassini lost track of it. Small dark storms like these generally get stretched out until they merge with the opposing currents to the north and south.
These little storms are the food that sustains the larger atmospheric features, including the larger ovals and the eastward and westward currents. If the little storms come from the giant thunderstorms, then together they form a food chain that harvests the energy of the deep atmosphere and helps maintain the powerful currents.


http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1399
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby Ion01 » Fri May 02, 2008 6:41 am

This image of saturn remindes me of one of the structures that ferrofluid takes in a changing magnetic field. I know there is a video our there which shows this but my playing is not cooperating so I can find it.
Image
User avatar
Ion01
 
Posts: 88
Joined: Mon Mar 17, 2008 6:37 am

Re: Saturn Currently Stormy.

Unread postby MGmirkin » Fri May 02, 2008 10:34 am

Ion01 wrote:This image of Saturn reminds me of one of the structures that ferrofluid takes in a changing magnetic field.


It's also reminiscent of the Dragon Storm which I think Wal Thornhill has likened to a diocotron instability.

Image

Image

Cheers,
~Michael Gmirkin
"The purpose of science is to investigate the unexplained, not to explain the uninvestigated." ~Dr. Stephen Rorke
"For every PhD there is an equal and opposite PhD." ~Gibson's law
User avatar
MGmirkin
Moderator
 
Posts: 1667
Joined: Thu Mar 13, 2008 11:00 pm
Location: Beaverton, Oregon, USA

Wave In Upper Atmosphere

Unread postby StefanR » Thu May 08, 2008 9:19 am

Saturn's Infrared Temperature Snapshot
Wave In Upper Atmosphere

The discovery of the wave pattern is the result of a 22-year campaign observing Saturn from Earth (the longest study of temperature outside Earth ever recorded), and the Cassini spacecraft's observations of temperature changes in the giant planet's atmosphere over time.

The Cassini infrared results, which appear in the same issue of Nature as the data from the 22-year ground-based observing campaign, indicate that Saturn's wave pattern is similar to a pattern found in Earth's upper atmosphere. The earthly oscillation takes about two years. A similar pattern on Jupiter takes more than four Earth years. The new Saturn findings add a common link to the three planets.

Just as scientists have been studying climate changes in Earth's atmosphere for long periods of time, NASA scientists have been studying changes in Saturn's atmosphere. Glenn Orton of NASA's Jet Propulsion Laboratory in Pasadena, Calif., says patience is the key to studying changes over the course of a Saturnian year, the equivalent of about 30 Earth years.
Image
The wave pattern is called an atmospheric oscillation. It ripples back and forth within Saturn's upper atmosphere. In this region, temperatures switch from one altitude to the next in a candy cane-like, striped, hot-cold pattern. These varying temperatures force the wind in the region to keep changing direction from east to west, jumping back and forth. As a result, the entire region oscillates like a wave.

Cassini scientists hope to find out why this phenomenon on Saturn changes with the seasons, and why the temperature switchover happens when the sun is directly over Saturn's equator.

http://saturn.jpl.nasa.gov/news/features/feature20080507.cfm
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby Ion01 » Wed May 14, 2008 11:08 am

Here is what I was thinking it reminded me of, the third image down on the right: http://web.mit.edu/newsoffice/2003/ferrofluid-0205.html
User avatar
Ion01
 
Posts: 88
Joined: Mon Mar 17, 2008 6:37 am

Re: Saturn Currently Stormy.

Unread postby Grey Cloud » Wed May 14, 2008 11:29 am

Ion01 wrote:Here is what I was thinking it reminded me of, the third image down on the right: http://web.mit.edu/newsoffice/2003/ferrofluid-0205.html


Nice images. Don't they bring us back to petraglyphs? And cymatics?
Last edited by Grey Cloud on Wed May 14, 2008 12:28 pm, edited 1 time in total.
If I have the least bit of knowledge
I will follow the great Way alone
and fear nothing but being sidetracked.
The great Way is simple
but people delight in complexity.
Tao Te Ching, 53.
Grey Cloud
 
Posts: 2477
Joined: Sun Apr 13, 2008 5:47 am
Location: NW UK

Re: Saturn Currently Stormy.

Unread postby starbiter » Wed May 14, 2008 11:41 am

This is Wal's take on the "Dragon Storm".
http://www.holoscience.com/news.php?article=xewq47rt
I Ching #49 The Image
Fire in the lake: the image of REVOLUTION
Thus the superior man
Sets the calender in order
And makes the seasons clear

www.EU-geology.com

http://www.michaelsteinbacher.com
User avatar
starbiter
 
Posts: 1445
Joined: Mon Mar 17, 2008 9:11 am
Location: Antelope CA

Re: Saturn Currently Stormy.

Unread postby MGmirkin » Wed May 14, 2008 4:24 pm

starbiter wrote:This is Wal's take on the "Dragon Storm".
http://www.holoscience.com/news.php?article=xewq47rt


Mentioned above:

MGmirkin wrote:
Ion01 wrote:This image of Saturn reminds me of one of the structures that ferrofluid takes in a changing magnetic field.


It's also reminiscent of the Dragon Storm which I think Wal Thornhill has likened to a diocotron instability.

[...]

Cheers,
~Michael Gmirkin


Cheers, again...
~Michael
"The purpose of science is to investigate the unexplained, not to explain the uninvestigated." ~Dr. Stephen Rorke
"For every PhD there is an equal and opposite PhD." ~Gibson's law
User avatar
MGmirkin
Moderator
 
Posts: 1667
Joined: Thu Mar 13, 2008 11:00 pm
Location: Beaverton, Oregon, USA

Re: Saturn Currently Stormy.

Unread postby StefanR » Tue Jun 03, 2008 3:37 am

Image
Sketch of the magnetosphere of Saturn, from Bagenal (1992).
Saturn's magnetosphere is large and fast (10-hr) rotating like that of Jupiter. It also has internal plasma and neutral sources in the icy satellites and the rings, both with ephemeral atmospheres, and also Titan, which has a dense atmosphere. However, unlike Io, Titan orbits in the outskirts of the system, sometimes inside of it and sometimes "outside" of it and directly exposed to the solar wind. The Kronian and Jovian magnetospheres therefore have dominant or at least substantial internal mass and rotational energy sources against an external solar wind control, in contrast to the case of the Earth. In the 1980-1981 Voyager encounters, Saturn's magnetic field was found to be surprisingly aligned with the spin axis, and presents a simpler system than Jupiter's because the field non-dipolar terms are much smaller. Saturn's aurora was also positively identified in UV emission and seemed to emanate from high latitude ovals thought to map to the magnetopause, although, as for Jupiter, the models and mapping are uncertain. Saturn' system may thus be controlled mainly by the solar wind interaction, rather than by internal forces. However, Voyager also revealed kilometric radio emissions (SKR) consisting of sychrotron radiation by precipitating auroral electrons. The SKR and some ring spokes showed some enhancements at a given magnetic longitude, thus indicating that longitudinal (and thus corotational) effects are at play as well. HST imaging will be key for untangling the behavior of Saturn's aurora and magnetosphere.

Image
Saturn in the far-ultraviolet (~1200-2100 Ang) in 1994 with the WFPC2 camera on HST. They were published by John Trauger et al. (1998). Saturn's disk and rings are seen in reflected sunlight (longwards of ~1600 Ang). The auroral emissions are easy to distinguish in the polar regions because those regions are dark in the UV due to UV-absorbing polar hydrocarbon hazes formed in turn by the auroral processes. Both emissions in H2 and H Lyman alpha are detected in these images. A strong auroral event was taking place in Saturn's morning aurora, as shown in the right figure.

Image
an HST press release also by Trauger et al., was obtained with the STIS instrument on HST. The STIS far-UV imaging mode has a about 10 times better sensitivity than a typical WFPC2 exposure, and about 4 times the spatial resolution (eg, the Cassini division of the rings is now clearly visible). Details of the aurora can now be better studied. The STIS far-UV MAMA detector covers the 1200-1800 Angstroms, so there is also less reflected sunlight as compared to the WFPC2 images. By 1997 the northern hemisphere of Saturn was barely observable. Brighter morning emission is seen on the outh east limb, while a more diffuse emission is seen in the afternoon. The auroral double structure seen on the south east limb is an artifact since the image is a summation of two STIS exposures. The double structure in turn shows that the aurora has temporal and/or longitudinal variations. The latter explanation implies that Saturn's magnetic field is not at dipolar as previously believed. The emissions also show a not too smooth oval (towards the central portion of the Earth-facing side of the auroral oval).


Image
The figure on the left is a composite of WFPC2 sub-images of Saturn's north aurora reported by Trauger et al. (1998) . They show temporal variations in Saturn's northern aurora. The top 4 panels show data obtained within about 5 hours on 9 October 1994 during the very first imaging of Saturn in the far-UV (of which the full first exposure is depicted on the left figure). Saturn was undergoing an auroral event, where bright emission remained fixed at 8 AM local time throughout the ~5 hours observing period. The auroral storm was dimming with time. Two observations taken on two separate dates in 1995 revealed very little auroral emission.


Saturn's aurora was known to be bursty from both Voyager and contemporaneous IUE observations, and we think that Voyager may have observed on such morning auroral event. Such events seem to be typical of fast-rotating magnetospheres. (On Jupiter the events are fixed at dawn rather than at 8 AM in magnetic local time.) More information on the temporal behavior of Saturn's aurora can be obtained from analysis of the newer STIS data, because these data was obtained in the STIS time-tag mode. Coordinated observations should be made in the years to come with the Cassini mission in-situ solar wind and magnetospheric measurements.

Because the rotational period of Saturn is highly uncertain, we do not know if the bursts of UV aurora enhancements are constrained in magnetic longitude. With HST imaging observations, made over extended periods and combined with Cassini in-situ data, we may be able to resolve this issue. The STIS images can also be used to resolve corotational versus magnetic local time effects from observing, like for Jupiter, throughout a good part of a planet rotation, as the features rotate from the morning to the afternoon.

http://vega.lpl.arizona.edu/~gilda/jovianplanets.html
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Tue Jun 10, 2008 7:30 am

Image

F Ring Dynamism
October 18, 2006 Full-Res: PIA08290

The Cassini spacecraft has revealed a never-before-seen level of detail in Saturn's F ring, including evidence for the perturbing effect of small moonlets orbiting in or close to the ring's bright core.
For some time, scientists have suspected the presence of tiny moonlets that orbit Saturn in association with the clumpy ring. As the small satellites move close to the F ring core they leave a gravitational signature. In some cases they can draw out material in the form of a "streamer"--a miniature version of the interaction Cassini has witnessed between Prometheus and the F ring material. The dynamics of this interaction are the same, but the scale is different. See Thieving Moon for a view of Prometheus creating a streamer.
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2330


Cassini sees collisions of moonlets on Saturn's ring
A team of scientists led from the UK has discovered that the rapid changes in Saturn's F ring can be attributed to small moonlets causing perturbations. Their results are reported in Nature (5th June 2008).
Image

Prof Carl Murray of Queen Mary, University of London and member of the Cassini Imaging Team led the analysis. He says “Saturn’s F ring is perhaps the most unusual and dynamic ring in the solar system; it has multiple structures with features changing on a variety of timescales from hours to years.”
Prof Murray adds “Previous research has noted the features in the F ring and concluded that either another moon of radius about 100km must be present and scattering the particles in the ring, or a much smaller moonlet was colliding with its constituent particles. We can now say that the moonlet is the most likely explanation and even confirm the identity of one culprit.”

Dr Sébastien Charnoz of Université Paris 7 / CEA Saclay is a co-author on the paper. He says “Large scale collisions happen in Saturn’s F ring almost daily – making it a unique place to study. We can now say that these collisions are responsible for the changing features we observe there.”

The Cassini images also show new features (called "fans") which result from the gravitational effect of small (~1km) satellites orbiting close to the F ring core.
http://www.scitech.ac.uk/PMC/PRel/STFC/CassColl.aspx

Image
The F ring resolves into five separate strands in this closeup view. Potato-shaped Prometheus is seen here, connected to the ringlets by a faint strand of material. Imaging scientists are not sure exactly how Prometheus is interacting with the F ring here, but they have speculated that the moon might be gravitationally pulling material away from the ring. The ringlets are disturbed in several other places. In some, discontinuities or "kinks" in the ringlets are seen; in others, gaps in the diffuse inner strands are seen. All these features appear to be due to the influence of Prometheus

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=878
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Tue Jun 10, 2008 1:11 pm

Kinks in Saturn's Rings

In previous Thunderbolts Picture of the Day articles about the plasmasphere around Saturn, it was noted that planets and moons do not exist in an electrically neutral environment. Saturn, in particular, has a family of moons that exhibit electric discharge machining on a vast scale, as well as features within its atmosphere that could be characterized as lightning discharges. Its aurora are an intense radio-emitter and the planet is surrounded by a torus of plasma that emits x-rays and extreme ultra-violet light. Saturn seems to display many aspects that are predicted by the Electric Universe theory, including the shape of its rings.

Bodies immersed in plasma aren't isolated, they are connected by circuits. Most of the time they are not in equilibrium because they are in unstable conditions. The majority of them are moving across the plasma filaments that exist in the solar system and in the plasmaspheres around planets. Currents in plasma contract into filaments (which are really sheets of double-layers folded into tubes) and the force between filaments is linear, so the electromagnetic fields created by the filaments are the most powerful long-range attractor in the universe.


http://www.thunderbolts.info/tpod/2007/arch07/071112saturnsrings.htm


The Tunguska Event (2)
Presence of microscopic glassy spherules over a large area.

The final result of the explosive fragmentation, melting and vaporization of the bolide will be a spray of glassy spherules beyond the point where the main plasma discharge and explosion took place. The creation of spherules by electric discharge and electrical fusing, a common effect of lightning, is now well demonstrated in the laboratory.
http://www.thunderbolts.info/tpod/2006/arch06/060203tunguska2.htm


Dusty Plasmas in the Laboratory, Industry, and Space

Charged microparticles are an annoyance in the plasmas of fusion energy schemes and semiconductor manufacturing. But in laboratory plasmas and in space, they can be uniquely informative.
Robert L. Merlino and John A. Goree

What do the rings of Saturn have in common with industrial reactors used to manufacture semiconductor microchips? Both are examples of systems containing charged dust particles whose dynamics are controlled by electromagnetic and gravitational forces. More specifically, they are examples of dusty plasmas, defined as partially or fully−ionized gases that contain micron−size particles of electrically charged solid material, either dielectric or conducting. Dusty plasmas are common in astrophysical environments; examples range from the interstellar medium to cometary tails and planetary ring systems.
http://www.thunderbolts.info/forum/phpBB3/viewtopic.php?f=3&t=159#p1532
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Re: Saturn Currently Stormy.

Unread postby StefanR » Sat Jun 14, 2008 9:40 am

Chandra Observation of an X-ray Flare at Saturn: Evidence for Direct
Solar Control on Saturn’s Disk X-ray Emissions
1. Introduction
Saturn and Jupiter are alike in many respects  both are giant magnetized planets with
huge magnetospheres and similar rotation rates. However, Saturn’s magnetosphere is
thought to be powered in a fashion intermediate between the Jovian case, which is largely
driven by the rapid rotation of Jupiter’s huge magnetic field with large internal sources of
plasma, and the Earth’s magnetosphere, whose dynamics are dominated by solar wind
interactions (Russell 2001; Waite & Lummerzheim 2002; Krupp et al. 2004; Clarke et al.
2005). Unlike Jupiter (offset angle 9.6°) or the Earth (11.5°), the magnetic dipole of Saturn
is closely aligned with the planetary spin axis (<1°). Auroral emissions from Saturn have
been observed at far ultraviolet (FUV), infrared and radio wavelengths (Bhardwaj &
Gladstone 2000a, 2000b; Gérard et al. 2004; Stallard et al. 2004; Kurth et al. 2005; Clarke
et al. 2005). Early attempts to detect X-ray emission from Saturn with Einstein in
December 1979 (Gilman et al. 1986) and ROSAT in April 1992 (Ness & Schmitt 2000)
were negative and marginal, respectively. Saturnian X-rays were unambiguously observed
by XMM-Newton in October 2002 (Ness et al. 2004a) and by the Chandra X-ray
Observatory (CXO) in April 2003 (Ness et al. 2004b).
Both Jupiter and Earth exhibit X-ray emission associated with their auroras and their nonauroral
(low-latitude) disks (see reviews by Bhardwaj et al. 2002; Waite & Lummerzheim
2002; Petrinec et al. 2000). The X-ray aurora on Earth is mainly generated by electron
bremsstrahlung (e.g., Stadsnes, Aarsnes, & Bjordal 1997; Petrinec et al. 2000; Bhardwaj et
al. 2005b), while Earth’s disk X-ray emissions are known to be produced due to scattering
and fluorescence of solar X-rays (McKenzie, Rugge, & Charles 1982; Snowden &
Freyberg 1993; Petrinec et al. 2000). Recent X-ray observations of Jupiter by Chandra and
XMM-Newton have confirmed, as proposed earlier (for review, see Bhardwaj and
Gladstone 2000a), that auroral X-rays of Jupiter are produced by charge-exchange of
precipitating highly-ionized heavy ions (Branduardi-Raymont et al. 2004; Elsner et al.
2005). However, these ions are not from the inner (~8–12 RJ; RJ = Jupiter radius)
magnetosphere, as thought earlier, but are from the outer (>30 RJ) magnetosphere or/and
solar wind, and apparently undergo large acceleration to attain energies of >1
MeV/nucleon before impacting on the Jovian upper atmosphere (Gladstone et al. 2002;
Cravens et al. 2003; Elsner et al. 2005). The disk X-ray emissions from Jupiter were
initially proposed to be largely due to the precipitation of ions from the radiation belts
(Waite et al. 1997), but recent observations (Gladstone et al. 1998; Bhardwaj et al. 2004,
2005a; Branduardi-Raymont et al. 2004) suggest that they are resonant and fluorescent
scattered solar X-rays (Maurellis et al. 2000; Bhardwaj et al. 2004, 2005a; Cravens et al.
2005).
In this letter, we present the first observation of an X-ray flare from Saturn’s disk. We also
demonstrate that, like on Jupiter, solar processes govern the production of X-ray emission
from the disk of Saturn.

http://arxiv.org/ftp/astro-ph/papers/0504/0504110.pdf

Like Jupiter, Saturn has a strong magnetic field so it was expected that Saturn would also show a concentration of X-rays toward the poles. However, Chandra's observation revealed instead an increased X-ray brightness in the equatorial region. Furthermore, Saturn's X-ray spectrum, or the distribution of its X-rays according to energy, was found to be similar to that of X-rays from the Sun. This indicates that Saturn's X-radiation is due to the reflection of solar X-rays by Saturn's atmosphere, the same process that may be responsible for the weak equatorial X-radiation observed from Jupiter. Further observations should help clarify whether Saturn's magnetic polar regions ever flare up in X-rays, as do Jupiter's.

Image
Chandra's image of Saturn held some surprises for the observers. First, Saturn's 90 megawatts of X-radiation is concentrated near the equator. This is different from a similar gaseous giant planet, Jupiter, where the most intense X-rays are associated with the strong magnetic field near its poles.

Saturn's X-ray spectrum, or the distribution of its X-rays according to energy, was found to be similar to that of X-rays from the Sun. This indicates that Saturn's X-radiation is due to the reflection of solar X-rays by Saturn's atmosphere. The intensity of these reflected X-rays was unexpectedly strong.

Further observations should help clarify the nature of Saturn's X-radiation, and determine whether Saturn's magnetic polar regions ever flare up in X-rays, as do Jupiter's. The features outside of Saturn's disk in the X-ray image are instrumental artifacts or "noise".
http://chandra.harvard.edu/xray_sources/solar_system7.html

Titre du document / Document title
X-ray emission from Saturn

Résumé / Abstract
We report the first unambiguous detection of X-ray emission originating from Saturn with a Chandra observation, duration 65.5 ks with ACIS-S3. Beyond the pure detection we analyze the spatial distribution of X-rays on the planetary surface, the light curve, and some spectral properties. The detection is based on 162 cts extracted from the ACIS-S3 chip within the optical disk of Saturn. We found no evidence for smaller or larger angular extent. The expected background level is 56 cts, i.e., the count rate is (1.6 ± 0.2) x 10-3 cts/s. The extracted photons are rather concentrated towards the equator of the apparent disk, while both polar caps have a relative photon deficit. The inclination angle of Saturn during the observation was ∼-27°, so that the northern hemisphere was not visible during the complete observation. In addition, it was occulted by the ring system. We found a small but significant photon excess at one edge of the ring system. The light curve shows a small dip twice at identical phases, but rotational modulation cannot be claimed at a significant level. Spectral modeling results in a number of statistically, but not necessarily physically, acceptable models. The X-ray flux level we calculate from the best-fit spectral models is ∼6.8 × 10-15 erg cm-2 s-1 (in the energy interval 0.1-2keV), which corresponds to an X-ray luminosity of ∼8.7 x 1014 erg s-1. A combination of scatter processes of solar X-rays require a relatively high albedo favoring internal processes, but a definitive explanation remains an open issue.
http://cat.inist.fr/?aModele=afficheN&cpsidt=15619622

Saturn X-ray (Chandra) images
http://www.mpe.mpg.de/~burwitz/objects/Saturn/

X-RAY EMISSION FROM JUPITER, SATURN, AND EARTH:
A SHORT REVIEW

Jupiter, Saturn, and Earth – the three planets having dense atmosphere
and a well developed magnetosphere – are known to emit X-rays.
Recently, Chandra X-ray Observatory has observed X-rays from these
planets, and XMM-Newton has observed them from Jupiter and Saturn.
These observations have provided improved morphological, temporal,
and spectral characteristics of X-rays from these planets. Both auroral
and non-auroral (low-latitude) ‘disk’ X-ray emissions have been
observed on Earth and Jupiter. X-rays have been detected from Saturn's
disk, but no convincing evidence for X-ray aurora on Saturn has been
observed. The non-auroral disk X-ray emissions from Jupiter, Saturn,
and Earth, are mostly produced due to scattering of solar X-rays. X-ray
aurora on Earth is mainly generated via bremsstrahlung from
precipitating electrons and on Jupiter via charge exchange of highlyionized
energetic heavy ions precipitating into the polar atmosphere.
Recent unpublished work suggests that at higher (>2 keV) energies
electron bremsstrahlung also plays a role in Jupiter’s X-ray aurora. This
paper summarizes the recent results of X-ray observations on Jupiter,
Saturn, and Earth mainly in the soft energy (~0.1-2.0 keV) band and
provides a comparative overview.


6. SATURN
The X-ray emission from Saturn was unambiguously detected by XMMNewton
in October 200239 and by Chandra in April 200340. X-rays were
detected mainly from the low-latitude disk and no clear indication of
auroral X-rays was observed.

Image
Chandra ACIS X-ray 0.24-2.0 keV images of Saturn on January 20, 26, 200441.
Each continuous observation lasted for one full Saturn rotation. The white scale bar in the
upper left of each panel represents 10?. The superposed graticule shows latitude and
longitude lines at intervals of 30?. The solid gray lines are the outlines of the planet and
rings, with the outer and inner edges of the ring system shown in white. The dotted white
line defines the region within which events were accepted as part of Saturn’s disk unless
obscured by the rings. The white oval around the south pole defines the polar cap region.


Recent Observation of Saturn (Fig. 10) by Chandra in January 2004
showed that X-rays from Saturn are highly variable – a factor of 2 to 4
variability in brightness in a week’s time41. In these observations an Xray
flare has been detected from the non-auroral disk of Saturn, which is
seen in direct response to an M6-class flare emanating from a sunspot
that was clearly visible from both Saturn and Earth (Fig. 11). This is the
first direct evidence suggesting that Saturn’s disk X-ray emission is
principally controlled by processes happening on the Sun41. Also a good
correlation has been observed between Saturn X-rays and F10.7 solar
activity index. The spectrum of X-rays from Saturn disk is very similar
to that from the disk of Jupiter (Fig. 12).
The Chandra observations in January 2004 also revealed X-rays from
Saturn’s south polar cap on Jan. 20 (see Fig. 10, left panel). However, the
analysis suggests41 that X-ray emissions from the south polar cap region
on Saturn are unlikely to be auroral in nature; they might instead be an
extension of its disk X-ray emission.

Image
Fig. 11. Light curve of X-rays from Saturn and the Sun on 20 January 200441. All data
are binned in 30 minute increments, except for the TIMED/SEE data, which are 3 minute
observation-averaged fluxes obtained every orbit (~12 measurements per day). (a)
Background-subtracted low-latitude (non-auroral) Saturn disk X-rays (0.24–2.0 keV)
observed by Chandra ACIS, plotted in black (after shifting by -2.236 hr to account for the
light-travel time difference between Sun-Saturn-Earth and Sun-Earth). The solar 0.2–2.5
keV fluxes measured by TIMED/SEE are denoted by open green circles and are joined by
the green dashed line for visualization purpose. (b) Solar X-ray flux in the 1.6–12.4 and
3.1–24.8 keV bands measured by the Earth-orbiting GOES-12 satellite. A sharp peak in
the light curve of Saturn’s disk X-ray flux— an X-ray flare— is observed at about 7.5 hr,
which corresponds in time and magnitude with an X-ray solar flare. In addition, the
temporal variation in Saturn’s disk X-ray flux during the time period prior to the flare is
similar to that seen in the solar X-ray flux.


7. Discussion
Table 2 presents a summary of the main characteristics of X-rays from
the three planets. X-rays from the low-latitude (non-auroral) disk of all
the three planets are mostly produced by scattering of solar X-rays by
atmospheric species. On Jupiter and Saturn the scattering is dominantly
resonant scattering with minor (~<10%) contribution from fluorescent
scattering34,38. However, not all the incident solar X-rays in the ~0.2–2.0
keV are scattered back. The energy-average geometric X-ray albedo of
Jupiter and Saturn over this energy range is ~5? 10-4 [ref. 35,41]. At
Jupiter precipitation of radiation belt ions can also make some
contribution to the disk X-rays33.

It has been suggested that the upper atmospheres of the giant planets
Saturn and Jupiter act as “diffuse mirrors” that backscatter solar X-rays.
Thus, these planets might be used as potential remote-sensing tools to
monitor X-ray flaring on portions of the hemisphere of the Sun facing
away from near-Earth space weather satellites35,38,41.

The X-ray aurora on Earth is generated by energetic electron
bremsstrahlung8-10. The auroral X-rays from Jupiter are produced by
charge-exchange of highly-ionized energetic heavy ions precipitating
from the outer magnetosphere and/or solar wind1,25-30. At higher energies
(>2.0 keV) the auroral X-rays at Jupiter31 could be produced by electron
bremsstrahlung process. However, at lower (~<2.0 keV) energies
electron bremsstrahlung falls short by orders of magnitude in explaining
the Jupiter auroral X-ray flux. Also the spectrum shape at lower energies
is inconsistent with the bremsstrahlung shape (see Figs. 6 and 9)26,37. At
Saturn there is no clear indication of an X-ray aurora40,41. X-ray aurora
produced by electron bremsstrahlung is expected at Saturn, but it will
probably be weak and could escape detection by present-day instruments,
because Saturn aurora is relatively weaker than that on Jupiter (see Table
1), and Saturn does not have copious heavy ion source, like Io on Jupiter.
Recently, XMM-Newton has observed Saturn, for two planet rotations,
in April and November 2005; the data is being analyzed.

In addition to X-rays from the planet itself, in the Jupiter system the Xray
emission has been observed from the Io plasma torus and from
Galilean satellites Io and Europa, while in the Saturn system X-rays
have been detected from the rings of Saturn
.

http://arxiv.org/ftp/astro-ph/papers/0605/0605282.pdf
The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.
User avatar
StefanR
 
Posts: 1371
Joined: Sun Mar 16, 2008 8:31 pm
Location: Amsterdam

Next

Return to Electric Universe - Planetary Science

Who is online

Users browsing this forum: No registered users and 2 guests

cron