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View Full Version : Why Haven't Gas Gaints Been Photographed At The Limb To View Cloud Structure?



Mr. Milton Banana
2009-Jan-01, 09:50 PM
I have seen photos taken at Earth's limb, where you could see cloud structures (like thunderstorms), as well as see the blue sky and sun-lit horizon.

Why hasn't this been done at Jupiter and Saturn? I imagine you could see some incredible vistas. I'm thinking in particular the super-cyclone at Saturn's south pole, where it has been reported by Cassini scientists that there are massive cumulonimbus clouds climbing as high as 45 miles above the cyclone.

To me, it seems like a wasted opportunity. We've had all those shots looking down at Jupiter and Saturn's clouds, and we've also had shots looking at each planet with the sun lighting them from behind-I'm thinking in particular of the shot of Saturn back-lit by the sun, where you see that sliver of the planet's contour lit up around its circumference.

Zooming into that sliver could have revealed what it would be like to fly above Saturn's clouds, and what we would see.

Jerry
2009-Jan-01, 10:36 PM
Cassini is taking these types of images of Saturn, Titan and Enceladus. I think there were also limb photos of Jupiter by Cassini; as well as many limb shots by Galileo.

StupendousMan
2009-Jan-02, 12:11 AM
I have seen photos taken at Earth's limb, where you could see cloud structures (like thunderstorms), as well as see the blue sky and sun-lit horizon.

Why hasn't this been done at Jupiter and Saturn?

It has. You just don't hear much about it because the pictures
aren't considered pretty, or worthy of press releases.
In addition, some of the most informative measurements are
made by monitoring a star (or the Sun) as it sets or rises behind
the limb of the planet. These occultation studies also produce little
in the way of pretty pictures.

I went to ADS (http://adsabs.harvard.edu/abstract_service.html)
and ran a quick search using keywords inspired by your message.
Some of the first items which returned were

Cassini UVIS Observation of Occultation of Sigma Leo by Jupiter (http://adsabs.harvard.edu/abs/2001DPS....33.0907C)

Fine-Scale Structure in Titan's High Haze (http://adsabs.harvard.edu/abs/2006AGUFM.P21B..01W)

Saturn Thermospheric Neutral Densities and Temperatures from Cassini UVIS (http://adsabs.harvard.edu/abs/2008cosp...37.2840S)

Perhaps you might try reading these papers (the abstracts are
certainly available for free), and do a little searching for
yourself.

Doodler
2009-Jan-02, 12:48 PM
The Hubble was recently doing a series of limb studies of Jupiter as Ganymeade was passing behind it.

Nick Theodorakis
2009-Jan-06, 01:03 PM
The Hubble was recently doing a series of limb studies of Jupiter as Ganymeade was passing behind it.

Featured on the January 6, 2009 APOD (http://antwrp.gsfc.nasa.gov/apod/ap090106.html).

Nick

Mr. Milton Banana
2009-Jan-08, 11:55 PM
Actually, I'm thinking more of an example like this:

http://earthobservatory.nasa.gov/IOTD/view.php?id=3338

This is earth. The type of picture I'm talking about is the top one. Here, you can actually see the sky and clouds, along with the sunset.

Here's another one-this time with cloud structure. Some thunderheads are rising in this one:

http://physics.uwyo.edu/~ddale/teach/99_00/swarthmore/earth_limb.jpg

Another EXCELLENT shot:

http://i207.photobucket.com/albums/bb307/cdo908/222904main_iss007e10974_lores.jpg

And this one:

http://science.ksc.nasa.gov/mirrors/images/images/pao/STS47/10064973.jpg

These last two, in particular, are what I'm talking about. Why can't we take similar photos of Jupiter and Saturn? I will say that we came pretty close with that great shot of the monster storm over Saturn's south pole. Now, if we could only get more detail of that.

StupendousMan
2009-Jan-09, 02:28 AM
Actually, I'm thinking more of an example like this:

http://earthobservatory.nasa.gov/IOTD/view.php?id=3338

This is earth. The type of picture I'm talking about is the top one. Here, you can actually see the sky and clouds, along with the sunset. ...




Ask yourself about those pictures: how far above the Earth's atmosphere was the camera?

Now ask yourself: how far above Saturn's atmosphere is Cassini?

Mr. Milton Banana
2009-Jan-09, 04:00 AM
Ask yourself about those pictures: how far above the Earth's atmosphere was the camera?

Now ask yourself: how far above Saturn's atmosphere is Cassini?

No, I'm thinking Cassini was far higher up (with Saturn being bigger)-but I guess Cassini doesn't have a zoom capable of capturing something similar?

I admit my ignorance-which is why I'm asking about this.

StupendousMan
2009-Jan-09, 06:28 PM
No, I'm thinking Cassini was far higher up (with Saturn being bigger)-but I guess Cassini doesn't have a zoom capable of capturing something similar?

I admit my ignorance-which is why I'm asking about this.

The pictures of Earth's atmosphere were taken from a few hundred kilometers
above the Earth's atmosphere, using big, powerful lenses.

Cassini has big, powerful lenses, but it's a LOT higher above Saturn's
atmosphere. Occasionally, it makes brief passes "close" to the upper
atmosphere, but it's still much more than a few hundred km. You could
go to NASA's Cassini sites and find out just how close it gets, if
you want to know.