Class 19 - Giant Planets 3

Reading - New Solar System - Chapter 15 - and these 2 pages from the introduction to the Jupiter book (written by Tim Dowling).

Lightening Storms

Short-lived (hours) convective clouds - with water - coming from deep (3 bars)

..accompanied by lightening (seen on the night side as visible flashes)

Dashes show bands of lightening - in cyclonic bands where the velocity is decreasing (increasing) with latitude in the northern (southern) hemisphere.

What Drives Jupiter's Weather?

2 models:

1 - Deep interior "flywheels" of concentric shells coupled to outer layers -> eddies which feed jets - BUT HOW?

2 - Surface layer de-coupled from deep interior, surface weather driven by:

A - solar flux - BUT what is latitudinal circulation that evens out equator-pole temperature gradient?

B - interior heat - BUT HOW?

this is the SATURN hexagon - probably a surface wave rather than deeply-seated. The hexagon was observed by Voyager - rendered here by an artist - and not seen since by HST - or Cassini.

Wind speeds measured by the Galileo probe...

Are these just tropospheric winds driven deep by the downdraft? Are they coupled to the underlying "abyssal" flows?

 

How to Measure Deep Interior? Juno Mission!

To penetrate the clouds go to longer wavelengths....

First, let's look at what can be done from Earth with the Very Large Array radio telescope

so, you can get a hint of what id deep down below the clouds... but the radiation belts generate lots of radio noise

And at Saturn, the cold rings get in the way

So, let's go to Jupiter with a RADOMETER designed to get deeper - the Juno mission (currently under study, in competition with the Lunar Aitken Basin sample return mission - selection to be made this summer)

Juno is designed to address the issue of what's going on inside Jupiter - it will measure

gravity field - remember those Js from 3750?

Red line = model of deep, differential rotation

Dashed line = rigid rotation

The radiometer will probe the emissions coming from deep below the clouds in 6 wavebands

The aim is to distinguish between 2 models -

Top: large-scale flow dominates and the belt-zone structure penetrates to depts > 200 bars

Bottom: small-scale convection dominates and the belt-zone structure disappears below the water cloud base at 6 bars.

Vertical exaggeration is ~50

Saturn

Deeper clouds - harder to see weather

HST

Voyager - exaggerated color

Voyager - false color

Ground-based IR telescope

Cassini

Here is the CLOUDMOVIE..30Mb - huge, I know, perhaps Preston could get us a smaller one, just showing the clouds.

..............

"dragon" storm

 

Conclusion - very similar to Jupiter - less turbulence, deeper clouds - why such strong equatorial jet?

 

Uranus

The Voyager picture - right = false color. Pole ~ facing sun

Then, HST IR pictures - saw clouds!

And now AO from Keck can do even better!

 

Neptune

 

GIANT PLANET COMPARISONS