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Jupiter's Alien Atmosphere --New NASA Images & Insights



New images of Jupiter are the first to catch an invisible wave shaking up one of the giant planet's jet streams, an interaction that also takes place in Earth's atmosphere and influences the weather. The movies, made from images taken by NASA's Cassini spacecraft when it flew by Jupiter in 2000, are part of an in-depth study conducted by a team of scientists and amateur astronomers led by Amy Simon-Miller at NASA's Goddard Space Flight Center.

"This is the first time anyone has actually seen direct wave motion in one of Jupiter's jet streams," says Simon-Miller, the paper's lead author. "And by comparing this type of interaction in Earth's atmosphere to what happens on a planet as radically different as Jupiter, we can learn a lot about both planets."

Like Earth, Jupiter has several fast-moving jet streams that circle the globe. Earth's strongest and best known jet streams are those near the north and south poles; as these winds blow west to east, they take the scenic route, wandering north and south. What sets these jet streams on their meandering paths-and sometimes makes them blast Florida and other warm places with frigid air-are their encounters with slow-moving waves in Earth's atmosphere, called Rossby waves. 

In contrast, Jupiter's jet streams "have always appeared to be straight and narrow," says co-author John Rogers, who is the Jupiter Section Director of the British Astronomical Association, London, U.K., and one of the amateur astronomers involved in this study.

Rossby waves were identified on Jupiter about 20 years ago, in the northern hemisphere. Even so, the expected meandering winds could not be traced directly, and no evidence of them had been found in the southern hemisphere, which puzzled planetary scientists.

To get a more complete view, the team analyzed images taken by NASA's Voyager spacecraft, NASA's Hubble Space Telescope, and Cassini, as well as a decade's worth of observations made by amateur astronomers and compiled by the JUPOS project.

The movies zoom in on a single jet stream in Jupiter's southern hemisphere. A line of small, dark, v-shaped "chevrons" has formed along one edge of the jet stream and zips along west to east with the wind. Later, the well-ordered line starts to ripple, with each chevron moving up and down (north and south) in turn. And for the first time, it's clear that Jupiter's jet streams, like Earth's, wander off course.

"That's the signature of the Rossby wave," says David Choi, the postdoctoral fellow at NASA Goddard who strung together about a hundred Cassini images to make each time-lapse movie. "The chevrons in the fast-moving jet stream interact with the slower-moving Rossby wave, and that's when we see the chevrons oscillate."

The team's analysis also reveals that the chevrons are tied to a different type of wave in Jupiter's atmosphere, called a gravity inertia wave. Earth also has gravity inertia waves, and under proper conditions, these can be seen in repeating cloud patterns.

"A planet's atmosphere is a lot like the string of an instrument," says co-author Michael D. Allison of the NASA Goddard Institute for Space Studies in New York. "If you pluck the string, it can resonate at different frequencies, which we hear as different notes. In the same way, an atmosphere can resonate with different modes, which is why we find different kinds of waves."

Characterizing these waves should offer important clues to the layering of the deep atmosphere of Jupiter, which has so far been inaccessible to remote sensing, Allison adds. 

Crucial to the study was the complementary information that the team was able to retrieve from the detailed spacecraft images and the more complete visual record provided by amateur astronomers. For example, the high resolution of the spacecraft images made it possible to establish the top speed of the jet stream's wind, and then the amateur astronomers involved in the study looked through the ground-based images to find variations in the wind speed.

The team also relied on images that amateur astronomers had been gathering of a large, transient storm called the South Equatorial Disturbance. This visual record dates back to 1999, when members of the community spotted the most recent recurrence of the storm just south of Jupiter's equator. Analysis of these images revealed the dynamics of this storm and its impact on the chevrons. The team now thinks this storm, together with the Great Red Spot, accounts for many of the differences noted between the jet streams and Rossby waves on the two sides of Jupiter's equator. 

"We are just starting to investigate the long-term behavior of this alien atmosphere," says co-author Gianluigi Adamoli, an amateur astronomer in Italy. "Understanding the emerging analogies between Earth and Jupiter, as well as the obviously profound differences, helps us learn fundamentally what an atmosphere is and how it can behave."

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I was just thinking in my mind when maybe our Sun blows up and dissolves Jupiter a little more or it dissolves away first, and Europa and its' moons will thaw out, and what type of life will maybe take hold and if they live long enough, what will they think. Or will it be us surviving on there. Or will anything happen before then. Like meteors something. Or will Jupiter ever dissolve away to hold life.

Why all this fascination with Jupiter? It is not even the most interesting of planets. All the time, all I read on this website is Jupiter, jupiter, jupiter. When did Saturn ever get a look in? I mean, even Vivaldi when she was writing the Four Planets Suite for symphony choir spoke about Jupiter, Mars, Venus, and I think if my memory serves me well, Jupiter again. Jupiter was certainly in there once. They have Chevies on Jupiter? Well, that's news! Clearly, you've lost the plot. Chevies are only made in America.

A planet's atmosphere is a lot like the string of an instrument. Prof. McArthur has spouted a lot of rubbish in his or her career, but I actually quite like this analogy. Let's think what it means. It means that it has resonant frequency and when you string the string, or play it, or bow it, or something, then you're going to make a lot of noise, and I think we all know that that's what planets' atmospheres do. They make a lot of noise. Because our own planet's atmosphere is very close to us, we can only hear its noise but if Earth had no atmosphere, then all we would hear is the constant roar of Mars' atmosphere and Jupiter's atmosphere and the other ones'.

And strings, sometimes they break. And when you look at Earth's atmosphere, that's what ye see. It's broken. It's broken like a broken string. I look into the sky and all I see is brokenness, and the peoples in the world, they're gonna have to wake up very soon or one day they won't wake up at all. And I know that you think that I'm just some crazy environmental conspiracy theorist, but actually I am the conscience of the planet. Earth, that is, not Jupiter. I hate Jupiter.

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