APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

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APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby APOD Robot » Tue Feb 28, 2017 5:12 am

[img]https://apod.nasa.gov/apod/calendar/S_170228.jpg[/img] A White Oval Cloud on Jupiter from Juno

Explanation: This storm cloud on Jupiter is almost as large as the Earth. Known as a white oval, the swirling cloud is a high pressure system equivalent to an Earthly anticyclone. The cloud is one of a "string of pearls" ovals south of Jupiter's famous Great Red Spot. Possibly, the Great Red Spot is just a really large white oval than turned red. Surrounding clouds show interesting turbulence as they flow around and past the oval. The featured image was captured on February 2 as NASA's robotic spacecraft Juno made a new pass just above the cloud tops of the Jovian world. Over the next few years, Juno will continue to orbit and probe Jupiter, determine atmospheric water abundance, and attempt to determine if Jupiter has a solid surface beneath its thick clouds.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Night eyes » Tue Feb 28, 2017 7:20 am

Wow what a beautiful picture!

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby yasgur » Tue Feb 28, 2017 9:30 am

Looks like a van Gogh.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby neufer » Tue Feb 28, 2017 12:30 pm

Art Neuendorffer

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Tszabeau » Tue Feb 28, 2017 1:32 pm

Looks like the White Oval has an appendix.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Tue Feb 28, 2017 3:18 pm

It is worth noting that this image was made with a very unsophisticated camera, having a low pixel count, low dynamic range sensor (quite inferior to what is found on most amateur astronomical cameras and even a number of DSLRs these days). As an instrument not included in the primary scientific suite, but provided mainly for public outreach, it isn't allocated much bandwidth, so it doesn't provide a lot of images, and most are substantially compressed (lossy) before being returned. Still, a lot of this is made up for by the images it can collect when very, very close to the planet, providing an actual pixel resolution about eight times finer than the HST can achieve from Earth orbit.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby MarkBour » Tue Feb 28, 2017 4:56 pm

Chris Peterson wrote: ... As an instrument not included in the primary scientific suite, but provided mainly for public outreach ...

That's really an interesting description of it. Like, the people have to have some pretty images, right? I'm wondering if enough such pictures will be taken in ways that would allow for any close-in movies of cloud motion to be composed.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Tue Feb 28, 2017 5:19 pm

MarkBour wrote:
Chris Peterson wrote: ... As an instrument not included in the primary scientific suite, but provided mainly for public outreach ...

That's really an interesting description of it. Like, the people have to have some pretty images, right? I'm wondering if enough such pictures will be taken in ways that would allow for any close-in movies of cloud motion to be composed.

I doubt it. The camera can't take very many pictures given its very low bandwidth, and it only offers high resolution when close to the planet, where the orbital velocity is very high and the probe spends very little time. Also, the camera can only be aimed by orienting the entire probe, and they're not going to do much of that just for images if it in any way interferes with collecting data from the instruments that the mission was designed around.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby neufer » Tue Feb 28, 2017 5:22 pm

MarkBour wrote:
That's really an interesting description of it. Like, the people have to have some pretty images, right? I'm wondering if enough such pictures will be taken in ways that would allow for any close-in movies of cloud motion to be composed.

    Unlikely, with wind speeds of just ~0.1 km/s while
    Juno is moving just shy of escape velocity ~59.5 km/s
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Catalina » Tue Feb 28, 2017 6:04 pm

Are the white ovals or any other "storms" on Jupiter created and driven by the same forces and dynamics as ours here on Earth, temperature, latitude, etc.?

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Tue Feb 28, 2017 6:27 pm

Catalina wrote:Are the white ovals or any other "storms" on Jupiter created and driven by the same forces and dynamics as ours here on Earth, temperature, latitude, etc.?

I'd say broadly yes, although it's clearly a much more complex system, especially vertically.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby neufer » Tue Feb 28, 2017 7:47 pm

Chris Peterson wrote:
Catalina wrote:
Are the white ovals or any other "storms" on Jupiter created and driven by the same forces and dynamics as ours here on Earth, temperature, latitude, etc.?

I'd say broadly yes, although it's clearly a much more complex system, especially vertically.

Latitude is less important since half of Jupiter's warmth is generated internally (mostly through contraction).

https://en.wikipedia.org/wiki/Jupiter wrote:
<<The amount of heat produced inside [Jupiter] is similar to the total solar radiation it receives. This additional heat is generated by the Kelvin–Helmholtz mechanism through contraction. This process causes Jupiter to shrink by about 2 cm each year. When it was first formed, Jupiter was much hotter and was about twice its current diameter.>>
https://en.wikipedia.org/wiki/Atmospher ... _lightning wrote:
<<The storms on Jupiter are similar to thunderstorms on Earth. They reveal themselves via bright clumpy clouds about 1000 km in size, which appear from time to time in the belts' cyclonic regions, especially within the strong westward (retrograde) jets. In contrast to vortices, storms are short-lived phenomena; the strongest of them may exist for several months, while the average lifetime is only 3–4 days. They are believed to be due mainly to moist convection within Jupiter's troposphere. Storms are actually tall convective columns (plumes), which bring the wet air from the depths to the upper part of the troposphere, where it condenses in clouds. A typical vertical extent of Jovian storms is about 100 km; as they extend from a pressure level of about 5–7 bar, where the base of a hypothetical water cloud layer is located, to as high as 0.2–0.5 bar.

Storms on Jupiter are always associated with lightning. The imaging of the night–side hemisphere of Jupiter by Galileo and Cassini spacecraft revealed regular light flashes in Jovian belts and near the locations of the westward jets, particularly at 51°N, 56°S and 14°S latitudes. On Jupiter lighting strikes are on average a few times more powerful than those on Earth. However, they are less frequent; the light power emitted from a given area is similar to that on Earth. A few flashes have been detected in polar regions, making Jupiter the second known planet after Earth to exhibit polar lightning.>>
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby tnzkka » Tue Feb 28, 2017 8:40 pm

Just a question:
"Known as a white oval, the swirling cloud is a high pressure system equivalent to an Earthly anticyclone. " Does this statement include the assumption that the rotation of Jupiter 's axis and the rotation of Jupiter in its orbit round the sun are in the the same way as for planet Earth? ( Both counterclockwise if seen from high above the galactic plane? That is looking down to Earth is looking to the North Pole?)
TIA for an answer.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Tue Feb 28, 2017 9:07 pm

tnzkka wrote:Just a question:
"Known as a white oval, the swirling cloud is a high pressure system equivalent to an Earthly anticyclone. " Does this statement include the assumption that the rotation of Jupiter 's axis and the rotation of Jupiter in its orbit round the sun are in the the same way as for planet Earth? ( Both counterclockwise if seen from high above the galactic plane? That is looking down to Earth is looking to the North Pole?)
TIA for an answer.

You mean looking down on the Solar System from the north side of its plane... which is not close to being parallel to the galactic plane.

Yes, Jupiter, like all the planets, orbits the Sun in the same direction (CCW from above the plane of the Solar System). Almost all the planets (including Jupiter) also rotate counterclockwise (although some have a substantial tilt). Venus rotates clockwise, which may be due to an ancient collision or some sort of dynamical situation early in its formation. Uranus rotates CCW, but it is nearly tipped on its side, so the geometry is quite different.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby neufer » Tue Feb 28, 2017 9:49 pm

Chris Peterson wrote:
Uranus rotates CCW, but it is nearly tipped on its side, so the geometry is quite different.

If Uranus "is nearly tipped on its side" (i.e., <90°,) then it rotates clockwise (i.e., retrograde).

https://en.wikipedia.org/wiki/Uranus#Axial_tilt wrote:
<<The Uranian axis of rotation is approximately parallel with the plane of the Solar System, with an axial tilt of 97.77° (as defined by prograde rotation). This gives it seasonal changes completely unlike those of the other planets. Near the solstice, one pole faces the Sun continuously and the other faces away. Only a narrow strip around the equator experiences a rapid day–night cycle, but with the Sun low over the horizon. At the other side of Uranus's orbit the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. Near the time of the equinoxes, the Sun faces the equator of Uranus giving a period of day–night cycles similar to those seen on most of the other planets. In contrast to the other planets, whose motions around the Sun resemble that of spinning tops, Uranus's motion can be visualised as that of a ball rolling on the ecliptic plane near solstices and of a spinning rifle bullet near equinoxes.>>
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Tue Feb 28, 2017 9:58 pm

neufer wrote:
Chris Peterson wrote:Uranus rotates CCW, but it is nearly tipped on its side, so the geometry is quite different.

If Uranus "is nearly tipped on its side" (i.e., <90°,) then it rotates clockwise (i.e., retrograde).

Yes, I guess it is tipped just below the plane (although that's still "nearly" on its side). Likewise for Pluto. Both rotate CW.
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Ann » Wed Mar 01, 2017 4:24 am

Chris Peterson wrote:It is worth noting that this image was made with a very unsophisticated camera, having a low pixel count, low dynamic range sensor (quite inferior to what is found on most amateur astronomical cameras and even a number of DSLRs these days). As an instrument not included in the primary scientific suite, but provided mainly for public outreach, it isn't allocated much bandwidth, so it doesn't provide a lot of images, and most are substantially compressed (lossy) before being returned. Still, a lot of this is made up for by the images it can collect when very, very close to the planet, providing an actual pixel resolution about eight times finer than the HST can achieve from Earth orbit.


I'm really late to the party here, but... wow. This is a picture of little scientific worth, taken with an inferior instrument, produced mostly for the benefit of the easily impressed, not tremendously highly educated and anything but Mensa-worthy general public.

Count me in among them. I went Wow!!! when I saw this image. And I said to myself, well, Saturn has the most beautiful "profile" in the Solar system (because the rings have to be counted as a part of the "profile" of the sixth planet), but Jupiter sure as heck wins the prize for the most stunningly amazingly beautiful cloud tops.

Wow!!! That's all I can say!

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby tnzkka » Wed Mar 01, 2017 1:29 pm

My thanks to Chris Peterson for his prompt answer dated Feb 28, 9.07pm. (My question was just above Chris' answer)

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby chuckster » Wed Mar 01, 2017 7:57 pm

In an old NOVA documentary on chaos theory some mathematics profs at a Texas university set up a rotating tank of fluid, then introduced colored dyes, while a rotating movie camera above observed the results. A stable but slowly orbiting "Great Red Spot" spontaneously organized itself, and started walking around the tank.

All the talk about low-res public outreach images saddens me. I'd love to have a large, full-color high res photo of the GRS and its surrounding swirls and bands printed and framed. Abstract art from Mother Nature.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby ntheartist » Wed Mar 08, 2017 9:38 am

The word 'Oval' does not apply for the cloud on Jupiter. It should have been 'Ellipse'. An oval is a definitely different shape, being two half circles connected by straight lines (like a modeltraintrack), while an ellipse is a circle in perspective.

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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby neufer » Wed Mar 08, 2017 12:57 pm

ntheartist wrote:
<<The word 'Oval' does not apply for the cloud on Jupiter. It should have been 'Ellipse'. An oval is a definitely different shape, being two half circles connected by straight lines (like a modeltraintrack), while an ellipse is a circle in perspective.

    Seinfeld: Why do they call it Ovaltine? The mug is round. The jar is round... They should call it Roundtine.
https://en.wikipedia.org/wiki/Oval wrote:
<<An oval (from Latin ovum, "egg") is a closed curve in a plane which "loosely" resembles the outline of an egg. The term is not very specific, but in some areas (projective geometry, technical drawing, etc.) it is given a more precise definition, which may include either one or two axes of symmetry. In common English, the term is used in a broader sense: any shape which reminds one of an egg. The three-dimensional version of an oval is called an ovoid.

The term oval when used to describe curves in geometry is not well-defined, except in the context of projective geometry. Many distinct curves are commonly called ovals or are said to have an "oval shape". Generally, to be called an oval, a plane curve should resemble the outline of an egg or an ellipse. In particular, these are common traits of ovals:

    they are differentiable (smooth-looking), simple (not self-intersecting), convex, closed, plane curves;

    their shape does not depart much from that of an ellipse, and

    there is at least one axis of symmetry.>>
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Re: APOD: A White Oval Cloud on Jupiter from Juno (2017 Feb 28)

Postby Chris Peterson » Wed Mar 08, 2017 2:44 pm

ntheartist wrote:The word 'Oval' does not apply for the cloud on Jupiter. It should have been 'Ellipse'. An oval is a definitely different shape, being two half circles connected by straight lines (like a modeltraintrack), while an ellipse is a circle in perspective.

But white ovals (and other cyclonic storm systems) on Jupiter are not circular phenomena seen obliquely. "Oval" is a better word than "ellipse" precisely because it is more loosely defined. Anything that looks roughly like a squashed circle (including a perfect ellipse with e>0) can be called "oval", whereas "ellipse" refers to a specific mathematical shape- which makes it technically incorrect in the case of white ovals.
Chris

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