Starship Asterisk*

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.

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:

[b][color=#0000FF]This oval, with only one axis of symmetry, resembles a chicken egg.[/color][/b]

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<<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.>>

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.

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).

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

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.>>

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.

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.

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/Atmosphere_of_Jupiter#Storms_and_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.>>

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.?

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

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.

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