a1 10 gas giants

The Gas GiantsLACC §10.1, 10.2, 10.3

• Understand what conditions and processes shaped the gas giant planets

• Understand what gives each planet it’s color: Jupiter--orange and brown belts, Saturn--yellow, Uranus and Neptune--blue (green)

• Know the oddities of each planet

An attempt to answer the “big question”: what is out there?

1Thursday, March 18, 2010

Condensation then Accretion

http://csep10.phys.utk.edu/astr161/lect/solarsys/scale.html

Near the sun, i.e. within the frost line, temperatures where higher (>150 K, -190°F). Volatile materials, hydrogen compounds, remained gaseous and did not condense:

• water (H2O)

• ammonia (HN3)

• methane (CH4)




Gas Giants: Mass & Size

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=Gallery


Jupiter’s mass is less than 1/1000th the sun’s






Gas Giants: the Sun in the Sky

The sun is about 0.5° across as it appears from Earth

(These planets are not to scale.)

0.10°, 1/5th3.7% as bright

0.06°, 1/8th1.1% as bright

0.03°, 1/17th0.3% as bright

0.02°, 1/25th0.1% as bright


Gas Giants: Interiors

http://solarsystem.nasa.gov/multimedia/gallery.cfm?Page=29




Jupiter: Interior

http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap11/FG11_10.jpg

-250°F

80°F

19000°F

44500°F

71500°F




Our knowledge of the internal structure of Uranus is inferred from the planet's radius, mass, period of rotation, the shape of its gravitational field and the behavior of hydrogen, helium, and water at high pressure. Its internal structure is similar to that of Neptune except for the fact that it is less active in terms of atmospheric dynamics and interior heat flow.

Uranus: Interior

http://www.trinity.wa.edu.au/intranet/subjects/astronomy/My%20Webs/Yr%208%20Astro/Uranus.htm




http://astro.unl.edu/classaction/solar.html



















Gas Giants: Atmospheres

http://www.astro.washington.edu/users/larson/Astro150b/Lectures/JupSatUraNep/jupsaturanept.html#atmospheres

Jupiter • Hydrogen: 86.1% • Helium: 13.6% • Methane: 0.1% • Ammonia: 0.02% • Water Vapor: 0.2% ?Saturn • Hydrogen: 92.4% • Helium: 7.4% • Methane: 0.2% • Ammonia: 0.02% • Water Vapor: 0.4% ?

Uranus • Hydrogen: 83% • Helium: 15% • Methane: 2%Neptune • Hydrogen: 85% • Helium: 13% • Methane: 2%

(Percent by volume)


http://www.astro.washington.edu/users/larson/Astro150b/Lectures/JupSatUraNep/jupsaturanept.html%23atmospheres




Gas Giants: Clouds

http://astronomyonline.org/SolarSystem/NeptuneIntroduction.asp

Different compounds form clouds at different temperatures. From warmest to coolest:

• H2O 32°F

• (NH4)SH -100°F

• NH3 -190°F

• CH4 -325°F




Gas Giants: Clouds

http://lasp.colorado.edu/~bagenal/3720/CLASS17/17GiantPlanets1.html




Jupiter: Between Cloud Layers

http://apod.nasa.gov/apod/ap000429.html




Jupiter: Orange and White

http://ciclops.org/view.php?id=110&js=1

Explanation: What makes the colors in Jupiter's clouds? With a mean temperature of 120 degrees Kelvin (-153 degrees Celsius) and a composition dominated by Hydrogen (about 90%), and Helium (about 10%) with a smattering of hydrogen compounds like methane and ammonia, astronomers have been hard pressed to explain the blue, orange and brown cloud bands and the salmon colored "red" spot. Trouble is -- at the cool cloud temperatures Jupiter's atmospheric constituents should be colorless! Some suggest that more colorful hydrogen compounds well up from warmer regions in the atmosphere, tinting the cloud tops. Alternatively, compounds of trace elements like sulfur may color the clouds. The colors do indicate the clouds' altitudes, blue is lowest through red as highest. The dark colored bands are called belts and the light colored ones zones. In addition to the belts and zones, the Voyager missions revealed the presence of intricate vortices visible, for example, in this 1979 image from the Voyager I flyby. Centuries of visual observations of Jupiter have revealed that the colors of its clouds are ever changing.




http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-jupiter.html




http://www.unidata.ucar.edu/staff/blynds/tmp.html

http://www.unidata.ucar.edu/staff/blynds/tmp.html



http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html




http://nssdc.gsfc.nasa.gov/photo_gallery/caption/redspot.txt








Jupiter: Belts and Zones

http://zebu.uoregon.edu/~imamura/121/lecture-13/jupiter_atmosphere.html

Jupiter's thick atmosphere is striped by wind-driven cloud bands that remain fixed in latitude - dark ... belts [and] light ... zones. At Jupiter's belt-zone boundaries the shearing wind velocities can reach nearly 300 miles per hour.










http://bang.lanl.gov/solarsys/jupiter.htm

http://bang.lanl.gov/solarsys/jupiter.htm

http://galileo.ivv.nasa.gov/callisto/030397.html








Jupiter: Great Red Spot

The Great Red Spot is a cold, high pressure area 2-3 times wider than planet Earth. Its outer edge rotates in a counter clockwise direction about once every six days. Jupiter's own rapid rotation period is a brief 10 hours.

http://apod.nasa.gov/apod/ap960802.htmlhttp://apod.nasa.gov/apod/ap960803.html


http://bang.lanl.gov/solarsys/raw/jup/jupiter3.avi






http://seds.lpl.arizona.edu/nineplanets/nineplanets/jupiter.html

http://seds.lpl.arizona.edu/nineplanets/nineplanets/jupiter.html

http://www.kalmbach.com/astro/Bytes/JUPITER.html

http://www.kalmbach.com/astro/Bytes/JUPITER.html





Saturn: Pale Yellow


compressed more than Saturn's, and the clouds are squeezed more closely together. The colors of Saturn's cloud layers, as well as the planet's overall butterscotch hue, are due to the same basic cloud chemistry as on Jupiter. However, because Saturn's clouds are thicker, there are few holes and gaps in the top layer, so we rarely glimpse the more colorful levels below. Instead, we see only different levels in the topmost layer, which accounts for Saturn's rather uniform appearance.

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?

imageID=506

The total thickness of the three cloud layers in Saturn's atmosphere is roughly 200 km, compared with about 80 km on Jupiter, and each layer is itself somewhat thicker than its counterpart on Jupiter. The reason for this difference is Saturn's weaker gravity.

At the haze level, Jupiter's gravitational field is nearly two and a half times stronger than Saturn's, so Jupiter's atmosphere is pulled much more powerfully toward the center of the planet. Thus Jupiter's atmosphere is




http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=506





Uranus: Pale Blue

http://www.spaceimages.com/urintrcoph.html

Beyond this boundary lies the hidden northern hemisphere of Uranus, which currently remains in total darkness as the planet rotates.

The picture is a composite of images taken through blue, green and orange filters. The darker shadings at the upper right of the disk correspond to the day-night boundary on the planet.

The blue-green color results from

the absorption of red light by

methane gas in Uranus' deep, cold

and remarkably clear atmosphere.




Uranus: Rotational Axis = 98°

http://www.ifa.hawaii.edu/~barnes/ast110_06/quizzes/disc02.html

• On Jupiter, the angle between incoming sunlight and the planet's axis of rotation is always about 90°. Consequently, Jupiter has no seasons!

• On Uranus, the angle between incoming sunlight and the planet's axis of rotation changes from 0° to 180° and back over the course of the planet's (84 yr!) orbit about the Sun. Consequently, Uranus has extreme seasons!




Neptune: Pale Blue

http://curious.astro.cornell.edu/question.php?number=236

...like in the case of Uranus the color is due to methane. The surface of Neptune appears darker than that of Uranus due to dimmer illumination (greater distance from the Sun).

http://www.wired.com/science/discoveries/news/2008/09/dayintech_0923












Neptune:Great Dark Spot

http://www.windows.ucar.edu/tour/link=/neptune/atmosphere/N_clouds_GDS.html&edu=high

Unlike Jupiter's Great Red Spot, the Great Dark Spot of Neptune is thought to be a hole in the methane cloud deck of Neptune. The white clouds shown in the picture are above the "hole". In many images of Neptune, the Great Dark Spot can be seen to change size and shape.

The Great Red Spot of Jupiter is thought to be a hurricane which has been raging on Jupiter for at least 400 years. The Great Dark Spot, seen here by Voyager in 1989, disappeared in 1994, and was replaced very soon by a similar "Spot" in a similar place, but in the northern hemisphere instead of in the southern hemisphere.




http://www.windows.ucar.edu/tour/link=/jupiter/atmosphere/J_clouds_GRS.html&edu=high

http://www.windows.ucar.edu/tour/link=/jupiter/atmosphere/J_clouds_GRS.html&edu=high

http://www.windows.ucar.edu/tour/link=/neptune/atmosphere/N_GDS_Hubble_1994.html&edu=high

http://www.windows.ucar.edu/tour/link=/neptune/atmosphere/N_GDS_Hubble_1994.html&edu=high

The Gas GiantsLACC §10.1, 10.2, 10.3

• Understand what conditions and processes shaped the gas giant planets: condensation beyond the frost line.

• Understand what gives each planet it’s color: Jupiter--Sulfur chemistry w/ (NH4)SH clouds, Saturn--Ammonia, NH3 cloud tops, Uranus and Neptune--Methane, CH4, cloud tops

• Know the oddities of each planet: Jupiter’s great red spot, Saturn’s low density, Uranus is on its side, Neptune is more massive than Uranus yet smaller.

An attempt to answer the “big question”: what is out there?


LACC Ch 10: Franknoi, Morrison, and Wolff, Voyages Through the Universe,

3rd ed.

• Ch. 10, pp. 240-241: 2, 4.

• Ch 10: Tutorial Quiz accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19Must Know: 5, 8, 9, 10, 11, 12, 13, 14, 18, 20Important: 7, 15, 17, 19

Due beginning of next class period.

Be thinking about your Solar System Project.


http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19






Rings of the Gas GiantsLACC §11.1, 11.4

• Understand what conditions and processes shaped the gas giant planets’ ring systems

• Know the ring systems in some detail

• Know why some rings are bright and some rings are dark

An attempt to answer the “big questions”: what is out there? Are we alone?


Ring Systems

http://www.jb.man.ac.uk/distance/strobel/solarsys/solsysb.htm




Ring Systems





Ring Systems

http://www.astro.rug.nl/%7Eetolstoy/ACTUEELONDERZOEK/JAAR2000/moons/aoz.html

Moons of Saturn: 1.Atlas 2.1980S27 3.1980S26 4.Janus 5.Epimetheus 6.Mimas 7.Enceladus 8.Telesto 9.Tethys 10.Calypso 11.Dione 12.1980S6 13.Rhea 14.Titan 15.Hyperion 16.Iapetus 17.Phoebe

Moons of Jupiter: 1.Metis 2.Adrastea 3.Amalthea 4.Thebe 5.Io 6.Europa 7.Ganymede 8.Callisto 9.Leda 10.Himalia 11.Lysithea 12.Elara 13.Ananke 14.Carme 15.Pasiphae 16.Sinope




Jupiter’s Ring

http://pds.jpl.nasa.gov/planets/captions/jupiter/jupring.htm

Jupiter's intricate, swirling ring system is formed by dust kicked up as interplanetary meteoroids smash into the giant planet's four small inner moons, according to... NASA's Galileo spacecraft.

http://www2.jpl.nasa.gov/galileo/status980915.html








Saturn’s Rings

http://pds.jpl.nasa.gov/planets/captions/saturn/2moons.htm

Most of the rings are only a few tens of meters thick with a total mass equivalent to a medium sized moon. The rings are made out of particles ranging from microscopic dust to barnyard sized boulders with perhaps a few kilometer-sized objects as well. ...the rings are composed mostly of ice crystals with some impurities.

Scientists once thought that the rings were formed at the same time, as the planets when they coalescing out of swirling clouds of interstellar gas 4.8 billion years ago. Under this model, remnants of material within the Roche limit could not condense and would become rings. However, in recent years this idea seems to be flawed. The rings appear to be young, perhaps only hundreds of millions of years old. One of the clues to this theory is that the rings are bright. As Saturn travels though space, the rings accumulate dust particles that have been darkened from solar radiation. If the rings were old, they should appear dark. Another theory suggests that perhaps a comet few too close to Saturn and tidal forces broke it into pieces.... Perhaps one of Saturn's moons was struck by an asteroid smashing it into the bits and pieces that form the rings.

http://www.solarviews.com/eng/saturnrings.htm








Saturn’s Rings

http://science.nasa.gov/headlines/y2002/12feb_rings.htm




Saturn’s Rings

http://www.dailymail.co.uk/sciencetech/article-1172205/Saturn-close-Sensational-cosmic-images-bring-ringed-planet-life.html

This image shows Saturn's rings and the shadow of nearby Mimas. They are now nearly edge-on toward the Sun, and long moon

shadows drape across them. Scientists are now studying the clumpy, disturbed ring material, stretching up to two miles above

the ring plane - contrasted with an estimated normal ring thickness of only six feet






Saturn’s Rings: Shepherd Moons


This composite of two images shows Pan, left, and Prometheus, right, in nearby rings. Pan is trailed by a series of edge waves in the outer boundary of the gap. Prometheus just touches the inner edge of Saturn's F ring, and is followed by a series of dark channels






Saturn’s Rings: New Ring Discovered in Infrared

http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2009-19a

This diagram highlights a slice of Saturn's largest ring. The ring (red band in inset photo)

was discovered by NASA's Spitzer Space Telescope, which detected infrared light, or heat, from the dusty ring material. Spitzer

viewed the ring edge-on from its Earth-trailing orbit around the sun.

The ring has a diameter equivalent to 300 Saturns lined up side to side. And it's thick too -- about 20 Saturns could fit into its vertical

height. The ring is tilted about 27 degrees from Saturn's main ring plane.




http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2009-19b





Saturn's newest halo is tilted at about 27 degrees from the main ring plane and encompasses the orbit of the moon Phoebe. Both the ring and Phoebe orbit in the opposite direction of Saturn's other rings

and most of its moons, including Titan and Iapetus.

Why did it take so long to find something so big? The answer is that the ring is very tenuous, made up of a sparse collection of ice and

dust particles. If you could transport yourself to the ring, you wouldn't even know you were there because the particles are so far apart. There's not a lot of sunlight out at Saturn, so this small density of particles doesn't reflect much visible light. Spitzer was able to spot

the band because it sees infrared light, or heat radiation, from objects. Even though the ring material is very cold, it still gives off

heat that can Spitzer can see.

Saturn’s Rings: New Ring Discovered in Infrared




Uranus’s Ring(s)

http://pds.jpl.nasa.gov/planets/captions/neptune/neprings.htm

Radio measurements showed the outermost ring, the epsilon, to be composed mostly of ice boulders several feet across. However, a very tenuous distribution of fine dust also seems to be spread throughout the ring system.

The particles that make up the rings may be remnants of a moon that was broken by a high-velocity impact or torn up by gravitational effects.

http://www.nineplanets.org/uranus.html






Shepherd Moons


Shepherd moons work in pairs on the inner and outer edge of rings to gravitational push and pull (accelerate and de-accelerate) ring particles. The result is to confine the ring particles to within the shepherd moons orbits.




http://astro.unl.edu/classaction/jovianplanets.html



















Neptune’s (Rings)

http://www.britannica.com/EBchecked/topic/409330/Neptune/54304/The-ring-system

The present rings are narrow, and scientists have found it difficult to explain how the orbits of the known moons can effectively confine the natural radial spreading of the rings. This has led many to speculate that Neptune’s present rings may be much younger than the planet itself, perhaps substantially less than a million years. The present ring system may be markedly different from any that existed a million years ago. It is even possible that the next spacecraft to visit Neptune’s rings will find a system greatly evolved from the one Voyager 2 imaged in 1989.

None of Neptune’s rings were detected from scattering effects on Voyager’s radio signal propagating through the rings, which indicates that they are nearly devoid of particles in the centimetre size range or larger. The fact that the rings were most visible in Voyager images when backlit by sunlight implies that they are largely populated by dust-sized particles, which scatter light forward much better than back toward the Sun and Earth.Their chemical makeup is not known, but, like the rings of Uranus, the surfaces of Neptune’s ring particles (and possibly the particles in their entirety) may be composed of radiation-darkened methane ices.




http://www.britannica.com/EBchecked/topic/409330/Neptune/54304/The-ring-system#




None of Neptune’s rings were detected from scattering effects on Voyager’s radio signal propagating through the rings, which indicates that they are nearly devoid of particles in the centimetre size range or larger. The fact that the rings were most visible in Voyager images when backlit by sunlight implies that they are largely populated by dust-sized particles, which scatter light forward much better than back toward the Sun and Earth.Their chemical makeup is not known, but, like the rings of Uranus, the surfaces of Neptune’s ring particles (and possibly the particles in their entirety) may be composed of radiation-darkened methane ices. The present rings are narrow, and scientists have found it difficult to explain how the orbits of the known moons can effectively confine the natural radial spreading of the rings. This has led many to speculate that Neptune’s present rings may be much younger than the planet itself, perhaps substantially less than a million years. The present ring system may be markedly different from any that existed a million years ago. It is even possible that the next spacecraft to visit Neptune’s rings will find a system greatly evolved from the one Voyager 2 imaged in 1989.

Neptune’s (Rings)









Rhea’s (Rings!? 6 March ‘08)

http://planetary.org/news/2008/0306_A_Ringed_Moon_of_Saturn_Cassini.html




Ring Systems

Ring systems are not stable; they evolve and change over time. Unless something replenishes them or keeps them from dissipating, they will not last longer than a few 100 millions years; one of Neptune’s might not last a century.

They generally form inside a planet’s Roche limit. Object’s that come closer than this distance to a planet tend to be ripped apart by tidal forces. Since the gas giants have strong gravitational fields, they have strong tidal forces.

Shepherding moons are moons that keep a ring system nice an tidy, by not letting material drift out of a ring and/or into gaps.


Rings of the Gas GiantsLACC §11.1, 11.4

• Understand what conditions and processes shaped the gas giant planets’ ring systems: Roche limit, shepherding moons

• Know the ring systems in some detail: Jupiter (dust from moons?), Saturn (recent break up of icy object?), Uranus (break up of a moon?), Neptune (unknown)

• Know why some rings are bright and some rings are dark: Bright = icy and young, Dark = dusty and old

An attempt to answer the “big questions”: what is out there? Are we alone?


• Ch 11, pp. 263-264: 9.

• Ch 11: Tutorial Quiz accessible from: http://www.brookscole.com/cgi-brookscole/course_products_bc.pl?fid=M20b&product_isbn_issn=9780495017899&discipline_number=19Must Know: 2, 3, 5, 6, 7, 9, 10, 12, 13, 15, 19, 20Important: 1, 4, 8, 11, 17, 18

Due at the beginning of next class period.

Be working your Solar System project.

HW Ch 11: Franknoi, Morrison, and Wolff, Voyages Through the Universe,

3rd ed.








a1 10 gas giants

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