Category: Jupiter

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Everyone loves twinkling stars and moonlit nights—EXCEPT astronomers. But astronomers are crafty people, so they’ve come up with ways to mitigate the distortion that Earth’s thick atmosphere causes for ground based telescopes (from which stars appear to twinkle). And now, a new image-correction technique has delivered the sharpest whole-planet ground-based picture ever. The Very Large Telescope (VLT) performed a record two-hour observation of Jupiter using a breakthrough technique to remove atmospheric blur. And what a result! Just take a look at that gorgeous image…And this new image reveals changes in Jupiter’s smog-like haze, probably in response to a planet-wide upheaval more than a year ago.

Being able to correct wide field images for atmospheric distortions has been the dream of scientists and engineers for decades. Astronomers used a new device called the Multi-Conjugate Adaptive Optics Demonstrator (MAD) prototype instrument mounted on ESO’s Very Large Telescope (VLT)
The new images of Jupiter prove the value of the advanced technology used by MAD, which uses two or more guide stars instead of one as references to remove the blur caused by atmospheric turbulence over a field of view thirty times larger than existing techniques.

“This type of adaptive optics has a big advantage for looking at large objects, such as planets, star clusters or nebulae,” says lead researcher Franck Marchis, from UC Berkeley and the SETI Institute in Mountain View, California, USA. “While regular adaptive optics provides excellent correction in a small field of view, MAD provides good correction over a larger area of sky. And in fact, were it not for MAD, we would not have been able to perform these amazing observations.”

MAD allowed the researchers to observe Jupiter for almost two hours on 16 and 17 August 2008, a record duration, according to the observing team. They were able to take a series of 265 snapshots. Conventional adaptive optics systems using a single Jupiter moon as reference cannot monitor Jupiter for so long because the moon moves too far from the planet. The Hubble Space Telescope cannot observe Jupiter continuously for more than about 50 minutes, because its view is regularly blocked by the Earth during Hubble’s 96-minute orbit.

Using MAD, ESO astronomer Paola Amico, MAD project manager Enrico Marchetti and Sébastien Tordo from the MAD team tracked two of Jupiter’s largest moons, Europa and Io – one on each side of the planet – to provide a good correction across the full disc of the planet. “It was the most challenging observation we performed with MAD, because we had to track with high accuracy two moons moving at different speeds, while simultaneously chasing Jupiter,” says Marchetti.

With this unique series of images, the team found a major alteration in the brightness of the equatorial haze, which lies in a 16,000-kilometer wide belt over Jupiter’s equator. More sunlight reflecting off upper atmospheric haze means that the amount of haze has increased, or that it has moved up to higher altitudes. “The brightest portion had shifted south by more than 6,000 kilometers,” explains team member Mike Wong.

This conclusion came after comparison with images taken in 2005 by Wong and colleague Imke de Pater using the Hubble Space Telescope. The Hubble images, taken at infrared wavelengths very close to those used for the VLT study, show more haze in the northern half of the bright Equatorial Zone, while the 2008 VLT images show a clear shift to the south.

“The change we see in the haze could be related to big changes in cloud patterns associated with last year’s planet-wide upheaval, but we need to look at more data to narrow down precisely when the changes occurred,” declares Wong

Source: ESO

As far as storms go, nothing will rival Jupiter’s Great Red Spot (GRS). But of interest is a smaller and newer storm called Oval BA, a giant anticyclone on Jupiter also known as Red Spot Junior. ‘Smaller’ is a relative term, as although Oval BA is about half the size of GRS, it has a diameter about the size of our Earth. It formed in 2000 as several vortices converged. However, recently Oval BA has undergone some changes. Suddenly it turned from white to red in a period of just a few months, and planetary scientists are trying to understand the processes that could cause the changes. While they are able to explain some of Red Spot Junior’s attributes, they are puzzled by others.

“Our group has made an in-depth analysis of all the aspects regarding the history and evolution of Oval BA,” said Dr. Santiago Pérez-Hoyos, of the Planetary Science Group of the University of the Basque Country in Spain. “The most strongly reddened region was an annulus around its centre. However, when we calibrated images taken with the Hubble Space Telescope, we found that it didn’t actually alter in red or infrared wavelengths during the period. Instead, it became darker in blue and ultraviolet wavelengths, which made it appear visually redder.”

The apparent reddening was first reported by amateur astronomers in early 2006, but it was not until April that professional astronomers were able to image the impressive alteration of the second largest storm in the Solar System after the Great Red Spot (GRS).

Using data from Cassini, the Hubble Space Telescope, NASA’s New Horizons mission and computer models the Planetary Science Group analyzed possible causes for the color change, including alterations to dynamical, photochemical and diffusion processes.

Pérez-Hoyos said, “The most likely cause appears to be an upward and inward diffusion of either a colored compound or a coating vapor that may interact later with high energy solar photons at the upper levels of Oval BA.”

The group were able to rule out that the reddening was caused by any dynamical processes. They found no change to the strength of the “hurricane” and, although some changes in the circulation around the spot had taken place, the maximum wind speeds (which may range up to 400 kilometers per hour or more) were consistent with measurements previous to 2000 of the storms that combined to form Oval BA.

The group modeled the wind flow in detail using high resolution simulations, in order to understand why the red material may be confined to the annulus region and how the color change happened in the observed time scales. The model accounts well for the temperature and wind structure inside the oval BA.

Models also showed that the change could not be attributed to interactions of Oval BA with the GRS, which were relatively close at the time. The flow around both vortices is in the zonal directions and is so strong that separates both storms

The oval height did not change over the period and there were no large changes in the temperature gradient of the oval.

Pérez-Hoyos said, “There is much to be understood about this problem yet. Future spacecraft missions and a continuous observation of the planet (as done by amateur astronomers) will surely give us new clues on the behaviour of Jupiter’s atmosphere that will result in a better understanding of it.”
The team presented their findings at the European Planetary Science Congress in Münster on Monday, 22nd September.

Source: European Planetary Conference

Jupiter appears to be breaking out with spots, as a third red storm has joined the Great Red Spot and Red Spot Jr. (or Oval BA) in the planet’s turbulent atmosphere. This third spot used to be a white storm, and its change to a red color might mean the storm is becoming more powerful. Astronomers believe these new images captured by both the Hubble and the Keck telescope may show that Jupiter is undergoing a major climate change, as was predicted four years ago.

“One of the most notable changes we observe in both the Hubble and Keck images is the change from a rather bland, quiescent band surrounding the Great Red Spot just over a year ago to one that is incredibly turbulent at both sides of the spot,” said Imke de Pater from the University of California Berkley. “During all previous HST observations and spacecraft encounters, starting with Voyager in 1979, such turbulence was seen only on the west or left side of the spot.”

The Great Red Spot has been around as long as 200 to 350 years, based on early telescopic observations. If the new red spot and the Great Red Spot continue on their courses, they will encounter each other in August. Astronomers will keep a close watch on whether the small oval will either be absorbed or repelled from the Great Red Spot. Red Spot Jr. which lies between the two other spots, and is at a lower latitude, will pass the Great Red Spot in June.

The Great Red Spot is a persistent, high-pressure storm whose cloud head sticks some 8 kilometers (5 miles) above the surrounding cloud deck. The new spot is much smaller than the other two and lies to the west of the Great Red Spot in the same latitude band of clouds.

The visible-light images were taken by Hubble’s Wide Field Planetary Camera 2 on May 9 and 10, and near-infrared adaptive optics images were taken by the W.M. Keck telescope on May 11.

These images may support the idea that Jupiter is in the midst of global climate change, as first proposed in 2004 by Phil Marcus, a professor of mechanical engineering at the University of California, Berkeley. The planet’s temperatures may be changing by 15 to 20 degrees Fahrenheit. The giant planet is getting warmer near the equator and cooler near the South Pole. He predicted that large changes would start in the southern hemisphere around 2006, causing the jet streams to become unstable and spawn new vortices.

“The appearance of the planet’s cloud system from just north of the equator down to 34 degrees south latitude keeps surprising us with changes and, in particular, with new cloud features tha haven’t been previously observed,” said Marcus. “Whether or not Jupiter’s climate has changed due to a predicted warming, the cloud activity over the last two and a half years shows dramatically that something unusual has happened.”

Original News Source: Hubble Press Release

Robotic spacecraft can gather a lot of data, and sometimes it takes years to sort through all the information acquired. Case in point: The Galileo spacecraft orbited Jupiter from 1995-2003. One discovery made by this mission was an anomaly in Jupiter’s rings. For the most part, the rings fall into the standard model of ring formation where the ring particles are shepherded by the orbits of four of Jupiter’s moons; Adrastea, Metis, Amalthea and Thebe (closest to farthest.) But a faint outward protrusion of dust extends beyond the orbit of Thebe, and scientists were mystified why this was occurring.

But a new study of data from the Galileo mission has found that this extension results from the interplay of shadow and sunlight on dust particles that make up the rings.

“It turns out that the outer ring’s extended boundary and other oddities in Jupiter’s rings really are ‘made in the shade,'” said Douglas Hamilton, a professor of astronomy at the University of Maryland. “As they orbit about the planet, dust grains in the rings alternately discharge and charge when they pass through the planet’s shadow. These systematic variations in dust particle electric charges interact with the planet’s powerful magnetic field. As a result small dust particles are pushed beyond the expected ring outer boundary, and very small grains even change their inclination, or orbital orientation, to the planet.”

The Galileo spacecraft was deliberately maneuvered to plunge into Jupiter in 2003 in an effort to protect one of its own discoveries – a possible ocean beneath the icy crust of the moon Europa (scientists didn’t want the spacecraft to one day impact and possibly contaminate Europa.) During this maneuver, the spacecraft dove through the rings and registered thousands of impacts from dust particles with its supersensitive dust detector.

Hamilton and German co-author Harald Krüger studied the impact data on dust grain sizes, speeds, and orbital orientations. Krüger analyzed the new data set and Hamilton created elaborate computer models that matched dust and imaging data on Jupiter’s rings and explained the observed unexpected behavior.

Take a look at Hamilton’s incredible models here.

“Within our model we can explain all essential structures of the dust ring we observed, ” said Krüger.

According to Hamilton, the mechanisms they identified affect the rings of any planet in any solar system, but the effects may not be as evident as it is at Jupiter. “The icy particles in Saturn’s famous rings are too large and heavy to be significantly shaped by this process, which is why similar anomalies are not seen there, ” he said. “Our findings on the effects of shadow may also shed some light on aspects of planetary formation because electrically charged dust particles must somehow combine into larger bodies from which planets and moons are ultimately formed.”

Original News Source: University of Maryland press release

Jupiter is a spotty place. There’s the aptly-named Great Red Spot – a large, long-lasting storm – that we all know and love, and new storms crop up every so often to create interesting features for astronomers both professional and amateur to study. The most recent discovery of new spots can only be seen in the UV, but they add a whole new level of complexity for scientists to chew on.

Io, one of Jupiter’s many moons, is volcanically active, and eruptions on the moon spew sulfur into the system. This sulfur is then ionized and swept up by Jupiter’s strong magnetosphere. Interactions between the ions and the magnetosphere cause aurora in the UV spectrum, similar to the phenomenon that makes the Northern Lights shine here on Earth. Io leaves a so-called ‘footprint’ on Jupiter in this way, and creates a glowing spiral shape on the northern and southern poles of the planet.

The rotation of Jupiter causes the spiral shape of the aurora: Io is ‘connected’ in one spot, and as Jupiter rotates it draws a glowing swirl of UV light around the pole. Astronomers had previously seen spots ‘downstream’ from the main spot caused by the interaction with Io, but these new images show a faint leading spot in front of the main one, essentially “upstream” in the flow of particles that causes the phenomenon.

A team from the University of Liège in Belgium discovered the spots in ultraviolet Hubble images taken of Jupiter. They found that when there were faint leading spots in one of the hemispheres, there were multiple spots in the other. The researchers propose that a beam of electrons is being transferred from one hemisphere to another, causing the fainter spots. The results of the study were published in the most recent edition of Geophysical Research Letters.

The image below illustrates the different mechanisms creating the auroral spots. The large torus around Jupiter is the plume of sulfur created by Io. The blue line between Io and Jupiter is where it is connected by the ionized sulfur, drawn in and funneled by Jupiter’s magnetosphere. The red lines illustrate the possible electron beams connecting the poles, which create the newly-discovered spots.

When Hubble is repaired in August, the researchers hope to take a closer look at the phenomenon and better understand this complex interaction.

Source: Eurekalert