Jupiter Archives

August 7, 2009December 24, 2015 by Tammy Plotner

Chasing An Occultation

Jupiter Occults Star - Leonard Ellul-Mercer

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You’ve all heard me talk about watching the Moon occult a bright star. That’s when we get a great example of stellar parallax from our Earthly viewpoint! But did you know that there are several other heavenly bodies that can cause an occultation that’s easy to view through an amateur telescope if you just know when and where to look? Then let’s take this opportunity to check it out…

On the night of August 3/4, 2009 Leonard Ellul-Mercer of Malta caught this while watching Jupiter!

Jupiter Occults 45 Capricorni Animation by Leonard Ellul-Mercer - Click to Animate — Jupiter Occults 45 Capricorni Animation by Leonard Ellul-Mercer - Click To Animate

What you’re seeing is a time lapse animation of the mighty Jove occulting HIP 107302, a 6th magnitude star you might know better as 45 Capricorni. How many of us may have glanced at something like that while making a cursory observation of the planet and taken it for a galiean moon? OK… It’s sixth magnitude. Not alot of you, but maybe you might not have watched long enough to know it would occult. (Besides, there’s a whole lot of cool things in that image. Watch the GRS float by, followed by the mushroom impact cloud and the whirl of the moons!)

So how do you go about getting predictions? There’s a wonderful set of worldwide resources that you can find through the International Occultation Timing Association (IOTA). This page will take you to their main frame where you can branch into several areas – including how to time occultations and submit your information. To find information on occultations by planets and asteroids for other areas of the world, be sure to visit the IOTA European section, too!

While you might watch an occultation just for fun, if you do decide to contribute your timing information you’re doing real science. By studying exactly the point in time when a star disappears and reappears, astronomers are able to take more accurate measurements of a planet or asteroid’s size and shape – and better calculate their distances at any given time. It’s a way to engage in new types of complimentary research that doesn’t require multi-million dollar equipment and gives back useful pertinent scientific data. After all, you might possibly discover a new moon of Jupiter – or one too small to be seen by your telescope – in just this way! Even a momentary dimming of a star might mean there’s something more there than meets the eye.

Enjoy your voyage of discovery! There are four major lunar events coming up during the month of August, including another Jupiter/star event for Europe. Get out there and have fun!

July 29, 2009December 24, 2015 by Tammy Plotner

Observe the Jupiter Impact Site!

July 28, 2009 Jupiter Impact Site by John Chumack

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Have you stayed up late and observed the Jupiter impact site? Then don’t be goofing around. Not since July 16-22, 1994 when comet Shoemaker-Levy crashed into Jupiter’s southern hemisphere have amateur astronomers had the opportunity to witness history firsthand! What makes me think that you can do it? Because I have…

Not only have cameras been clicking around the world, but they’ve been rolling, too.. Let’s take a look at one from John Chumack!

These images were done from his backyard Observatory in Dayton, Ohio USA, using A DMK 21F04 Fire-wire Camera and 2x Barlow, Optec Filter Wheel, attached to a Meade 10″ SCT scope. Captured images starting about 2:00 am and ran until 4:30 am E.ST. on 07-28-09. Basically 2.5 hours of rotation compressed to about 10 seconds. Way to go, John!!

If you think you have to be a professional, then think again. Even with less than perfect sky conditions, the impact site is very noticeable in a telescope as small as 4.5″ on a swimmy horizon and just gets better and easier to see as it reaches meridian and Jupiter reaches better sky position. DO NOT wait on the perfect night and the perfect time – because it just might not happen.

Another reason for my observations was to see just how close my predictions were… and without using a computer program? Hey… The old girl still has got it. Get thee out there on these Universal dates and times! July 29, 4:14, 14:20 and 23:59; July 30, 10:01 and 19:56; July 31, 5:52 and 15:48. For August 1, 01:43, 11:39, 21:34; August 2, 7:32 and 17:25; August 3, 3:23, 13:17 and 23:12; August 4, 9:08 and 19:03; August 5, 4:59 and 14:54; August 6, 0:50, 10:46 and 20:41; August 7, 6:37 and 16:32; August 8, 2:28, 12:24 and 22:18; August 9, 8:15 and 18:20; August 10, 4:06, 14:01, 23:57; August 11, 9:53 and 19:48; August 12, 5:42 and 15:39; August 13, 01:35, 11:31 and 21:26; August 14, 7:22 and 17:17; August 15, 3:13, 13:08, 23:04. I might be off by a few minutes, but I’m not that far off.

Take your time and do not just glance at Jupiter and think it’s not there at the predicted time – because it is. The charcoal gray oval is big enough and dark enough to stand out against the wash of the southern hemisphere, but sometimes you have to wait on a moment of clarity to see it. Try using a variety of color filters, but instead of installing them in the eyepiece, use the “blink” method. Hold the filter by the cell and simply set it on the eyepiece while you look through it, then take it off and look again. Once you see the mushroom cloud, you can’t “un-see” it.

History is waiting on you… Carpe noctem, baby!

Many, many thanks to John Chumack of Galactic Images for sharing this wonderful capture of what I was looking at last night and allowing me to adjust his original image to highlight the impact region!

July 24, 2009December 24, 2015 by Tammy Plotner

Viewing the Jupiter Impact With Your Telescope

Are you ready to stay up a little late and see if you can catch the new dark spot on Jupiter from what could have either been an asteroid or comet impact? It happened somewhere between July 17th and 19th and the scar is still fresh and visible. However, there is just a little bit you need to know to make your viewing the Jupiter impact through your telescope a success.

By July 21, Joe Brimacombe was on this phenomena and recording it. Says Joe: “Got very lucky: CBET 1882 just announced a transient new black spot on Jupiter’s south polar region that it a probable comet impact. By chance I’d been imaging Jupiter between gaps in the clouds and seem to have captured it just before it rotated out of view. Seeing conditions were above average for Cairns.”

And he did a video for us:

Of course, Jupiter and its surface features are one of the easiest targets for backyard telescopes – so seeing something that large – and dark against a light background – should be easy. Right? Wrong. Viewing through our own Earth’s atmosphere plays a huge role on how we see the atmosphere of Jupiter. Low horizon conditions, unsteady or turbulent air, thin clouds, humidity, temperature… all of these are key factors in planetary observing. Observing skills come only with experience, but given the time and effort – you CAN do it!

Before we go out to look for the impact, let’s stop and talk about Jupiter. There’s a reason so many amateurs love to this fast-rotating disk full of dynamic colored features… Because it’s so easy to see changes! Much like our own skin, the chemical composition of Jupiter’s atmosphere “tans” in the sunlight and the continual motion of its banded weather patterns keep an array of festoons, loops, ovals and barges on display at all times. How difficult is it to spot something? Then know this photo frame of a shadow transit is a 100% realistic view taken by me with a very small telescope with my camcorder. No tweaks, no filters… And it was much clearer to the eye than the camera. However, we need to remember that Jupiter rotates completely in about 10 hours, so a feature you see on its meridian at 11:00 pm won’t be there at 3:00 am. Like the “Great Red Spot”, the whole atmosphere is constantly on the move and there’s no guarantee that something that looks great one night will return again on another.

Now, let’s think positively! The impact spot is located near Jupiter’s System II longitude 210°. Although it’s small, if you use a lot of magnification, you should be able to spot it near the pole. The next thing you need to know is when to look! And here are the times the Jupiter impact can be seen for the next 10 days: July 25, 10:54 and 20:49; July 26, 6:45 and 16:41; July 27, 2:36, 12:32 and 22:27; July 28, 8:23 and 18:18; July 29, 4:14, 14:20 and 23:59; July 30, 10:01 and 19:56; July 31, 5:52 and 15:48. For August 1, 01:43, 11:39, 21:34; August 2, 7:32 and 17:25; August 3, 3:23, 13:17 and 23:12; August 4, 9:08 and 19:03; August 5, 4:59 and 14:54; August 6, 0:50, 10:46 and 20:41; August 7, 6:37 and 16:32; August 8, 2:28, 12:24 and 22:18; August 9, 8:15 and 18:20; August 10, 4:06, 14:01, 23:57; August 11, 9:53 and 19:48; August 12, 5:42 and 15:39; August 13, 01:35, 11:31 and 21:26; Auugst 14, 7:22 and 17:17; August 15, 3:13, 13:08, 23:04. Remember, these are very approximate Universal times when it should be visible on the meridian and you should have at least 20-30 minutes of opportunity on either side of the listed time to catch it as it rotates in and out.

Will the impact spot last in the days ahead? Unfortunately, just like the Shoemaker-Levy impact, the atmosphere will shred the debris cloud quickly. It is difficult enough to catch a feature near Jupiter’s poles because of limb darkening – so don’t wait to make your observations. Wishing you clear and steady skies!

Many thanks to Joe Brimacombe of Southern Galactic for sharing his incredible images with us!

July 23, 2009December 24, 2015 by Nancy Atkinson

New Image of Jupiter Impact in Infrared

This mid-infrared composite image was obtained with the Gemini North telescope on Mauna Kea, Hawai'i, on 22 July at ~13:30 UT with the MICHELLE mid-infrared spectrograph/imager. The impact site is the bright yellow spot at the center bottom of Jupiter's disk.

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After getting whacked unexpectedly by a small comet or asteroid, Jupiter is sporting a “bruise,” which has been big news this week. In visible wavelengths, the impact site appears as a black spot. But in a new image taken in near infrared by the Gemini North telescope on Mauna Kea, Hawai’i, the spot shows up in spectacular glowing yellow.

“We utilized the powerful mid-infrared capabilities of the Gemini telescope to record the impact’s effect on Jupiter’s upper atmosphere,” said Imke de Pater from the University of California, Berkeley. “At these wavelengths we receive thermal radiation (heat) from the planet’s upper atmosphere. The impact site is clearly much warmer than its surroundings, as shown by our image taken at an infrared wavelength of 18 microns.”

As Universe Today reported earlier, this new spot on Jupiter was first seen by Australian amateur astronomer Anthony Wesley on July 19th. This set off a flurry of activity as the large ground based observatories have imaged Jupiter in attempt to learn more about the impact and the object that struck Jupiter. Astronomers now say the object was likely a small comet or asteroid, just a few hundreds of meters in diameter. Such small bodies are nearly impossible to detect near or beyond Jupiter unless they reveal cometary activity, or, as in this case, make their presence known by impacting a giant planet.

In infrared, the impact site shows up in remarkable detail. “The structure of the impact site is eerily reminiscent of the larger Shoemaker-Levy 9 sites 15 years ago,” remarked Heidi Hammel (Space Science Institute), who was part of the team that supported the effort at Gemini. In 1994, Hammel led the Hubble Space Telescope team that imaged Jupiter when it was pummeled by a shattered comet. “The morphology is suggestive of an arc-like structure in the feature’s debris field,” Hammel noted.

The Gemini images were obtained with the MICHELLE spectrograph/imager, yielding a series of images at 7 different mid-infrared wavelengths. Two of the images (8.7 and 9.7 microns) were combined into a color composite image by Travis Rector at the University of Alaska, Anchorage to create the final false-color image. By using the full set of Gemini images taken over a range of wavelengths from 8 to 18 microns, the team will be able to disentangle the effects of temperature, ammonia abundance, and upper atmospheric aerosol content. Comparing these Gemini observations with past and future images will permit the team to study the evolution of features as Jupiter’s strong winds disperse them.

“The Gemini support staff made a heroic effort to get these data,” said de Pater. “We were on the telescope observing within 24 hours of contacting the observatory.” Because of the transient nature of this event, the telescope was scheduled as a “Target of Opportunity” and required staff to react quickly to the request.”

Source: Gemini Observatory

July 20, 2009December 24, 2015 by Nancy Atkinson

Jupiter Impact Confirmed

This image shows a large impact shown on the bottom left on Jupiter's south polar region captured on July 20, 2009, by NASA's Infrared Telescope Facility in Mauna Kea, Hawaii. Credit: NASA/JPL/Infrared Telescope Facility

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As we reported yesterday, an amateur astronomer snapped evidence of an impact on Jupiter. Now, NASA has confirmed the black spot on the giant gas planet is in fact an impact and not just a weather-related disturbance. And Anthony Wesley has now made the biggest observation of his life.

“It still feels very surreal right now,” he told Universe Today. “I guess it will take some time to really sink in (pun intended). I guess it shows that persistence and many hours at the scope eventually pays off.”

The Infrared Telescope Facility at the summit of Mauna Kea, Hawaii, has imaged the south polar region Jupiter, confirming the impact, which occurred on July 19. New infrared images show the likely impact point, with a visibly dark “scar” and bright upwelling particles in the upper atmosphere detected in near-infrared wavelengths, and a warming of the upper troposphere with possible extra emission from ammonia gas detected at mid-infrared wavelengths.

Anthony said imaging Jupiter has been his main passion since 2004. “It’s such a dynamic system that every image I take shows something new and different,” he said, “It keeps me coming back year after year, with bigger and better equipment each time. I never expected to see anything like this of course, but even the routine imaging of Jupiter’s storm systems can reveal a tremendous wealth of detail.”

Anthony said this is one of the areas where amateurs can make a significant contribution to science. “The the study of planetary atmospherics is a very hot topic at the moment and nowhere are the dynamics more evident than on Jupiter,” he said. “Researchers are coming to rely on amateur images of Jupiter for much of their data, augmented by professional images whenever something truly significant occurs that justifies the cost of using the larger instruments.”

Anthony Wesley from Canberra, Australia has captured a new impact spot on Jupiter. Credit: Anthony Wesley — Anthony Wesley from Canberra, Australia has captured a new impact spot on Jupiter. Credit: Anthony Wesle

“It’s significant that in each of the last 3 years amateurs have made the initial discoveries of new features in the Jovian atmosphere, the colour change of the previously white Oval BA to red in 2007 by Chris Go of the Philippines, the formation of another (smaller) red spot last year by myself, and then this event in 2009. In all cases the amateur work was followed up with imagery from Hubble and other major telescopes.”

This new impact occurred exactly 15 years after the first impacts by the comet Shoemaker-Levy 9, and as the celebrations of the Apollo 11 moon landings are taking place.

Glenn Orton, a scientist at JPL and his team of astronomers kicked into gear early in Monday morning and haven’t stopped tracking the planet. They are downloading data now and are working to get additional observing time on this and other telescopes.

“We were extremely lucky to be seeing Jupiter at exactly the right time, the right hour, the right side of Jupiter to witness the event. We couldn’t have planned it better,” he said.

The top image taken by the Infrared Telescope Facility, was taken at 1.65 microns, a wavelength sensitive to sunlight reflected from high in Jupiter’s atmosphere, and it shows both the bright center of the scar (bottom left) and the debris to its northwest (upper left).

“It could be the impact of a comet, but we don’t know for sure yet,” said Orton. “It’s been a whirlwind of a day, and this on the anniversary of the Shoemaker-Levy 9 and Apollo anniversaries is amazing.”

Shoemaker-Levy 9 was a comet that had been seen to break into many pieces before the pieces hit Jupiter in 1994.

Sources: JPL, email exchange with Anthony Wesley

July 19, 2009December 24, 2015 by Nancy Atkinson

Possible New Impact on Jupiter

Anthony Wesley from Canberra, Australia has captured a new impact spot on Jupiter. Credit: Anthony Wesle

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Amateur astronomer Anthony Wesley from Canberra, Australia captured an image of Jupiter on July 19 showing a possible new impact site. Anthony’s image shows a new dark spot in the South Polar Region of Jupiter, at approximately 216° longitude in System 2. It looks very similar to the impact marks made on Jupiter when comet Shoemaker-Levy 9 crashed into the gas giant in 1994. (But read the Bad Astronomer’s post that the black spot could also be weather.)

UPDATE (7/20): It has been confirmed this is an impact on Jupiter. Mike Salway shared the news Glenn Orton from JPL has imaged the Jupiter black spot with the NASA Infrared Telescope and he has confirmed it’s an impact.

The list below shows the times (in UT) when the black spot will be visible again (generated in WinJupos by Hans-Joerg Mettig), and found on the Mike Salway’s Ice In Space website.

2009 Jul 19 06:09 ( 216°) 16:05 ( 216°)
2009 Jul 20 02:00 ( 216°) 11:56 ( 216°) 21:52 ( 216°)
2009 Jul 21 07:47 ( 216°) 17:43 ( 216°)
2009 Jul 22 03:38 ( 216°) 13:34 ( 216°) 23:30 ( 216°)
2009 Jul 23 09:25 ( 216°) 19:21 ( 216°)
2009 Jul 24 05:16 ( 216°) 15:12 ( 216°)
2009 Jul 25 01:08 ( 216°) 11:03 ( 216°) 20:59 ( 216°)
2009 Jul 26 06:54 ( 216°) 16:50 ( 216°)
2009 Jul 27 02:45 ( 216°) 12:41 ( 216°) 22:37 ( 216°)
2009 Jul 28 08:32 ( 216°) 18:28 ( 216°)
2009 Jul 29 04:23 ( 216°) 14:19 ( 216°)2009
Jul 30 00:15 ( 216°) 10:10 ( 216°) 20:06 ( 216°)
2009 Jul 31 06:01 ( 216°) 15:57 ( 216°)

If you get the opportunity to observe or image this potential new discovery, please do.

On his observing blog, Anthony said he began observing Jupiter at approximately 11pm local time (1300UTC), using a 14.5″ Newtonian telescope. “I’d noticed a dark spot rotating into view in Jupiter’s south polar region and was starting to get curious,” he wrote. “When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I thought likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions also improved, I suddenly realized that it wasn’t just dark, it was black in all channels, meaning it was truly a black spot.”

First he thought it might be a dark moon (like Callisto) or a moon shadow, but it was in the wrong place and the wrong size. “Also I’d noticed it was moving too slow to be a moon or shadow. As far as I could see it was rotating in sync with a nearby white oval storm that I was very familiar with – this could only mean that the back feature was at the cloud level and not a projected shadow from a moon. I started to get excited.”

Hard-Hat tip to Mike Salway for alerting UT to the news.

June 17, 2009December 24, 2015 by Anne Minard

Jupiter’s Fiery Moon Io Could One Day Break Free, Go Dormant

Artist view of Io's heat loss induced by strong Jupiter's tides. Credit: V.Lainey, IMCCE-Paris Observatory

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Io may be close to thermal equilibrium, according to a study published this week in Nature. And if the new findings are correct, the volcanically wild moon could one day break free of Jupiter’s hold — and lose its rare, volcanic splendor.

Io is Jupiter’s innermost moon, and is the most volcanically active body in the Solar System. Its geological activity is thought to be the result of tidal heating from friction generated by the pull of Jupiter’s gravity. But it’s not known whether this internally generated tidal heat is high enough to generate the heat flow observed on Io’s surface.

Using astronomic observations made between 1891 and 2007, Valery Lainey, of the Observatoire de Paris in France, and colleagues have estimated the dissipation of tidal energy in Io by tracking its effect on the orbital motions of the innermost Galilean moons. For Io, the value is in good agreement with the observed surface heat flow and suggests that Io is close to thermal equilibrium. Jupiter’s tidal dissipation is close to the upper bound of its average value, as would be expected from the long-term evolution of the system.

“The measured secular accelerations indicate that Io is evolving inwards, towards Jupiter,” Lainey and her colleagues add, “and that the three innermost Galilean moons (Io, Europa and Ganymede) are evolving out of the exact Laplace resonance.”

In an accompanying editorial, Gerald Schubert of the University of California in Los Angeles, writes that “Io’s orbital imprisonment is the cause of its spectacular volcanism.”

“If it eventually breaks free, the most volcanically active object in our Solar System will become dormant.”

Source: Nature

February 25, 2009December 24, 2015 by Anne Minard

Jupiter, Saturn Plowed Through Asteroids, Study Says

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When Mars and Jupiter migrated to their present orbits around 4 billion years ago, they left scars in the asteroids belt that are still visible today.

The evidence is unveiled in a new paper in this week’s issue of the journal Nature, by planetary scientists David Minton and Renu Malhotra from the University of Arizona in Tucson.

The asteroid belt has long been known to harbor gaps, called Kirkwood gaps, in distinct locations. Some of these gaps correspond to unstable zones, where the modern-day gravitational influence of Jupiter and Saturn eject asteroids. But for the first time, Minton and Malhotra have noticed that some clearings don’t fit the bill.

“What we found was that many regions are depleted in asteroids relative to other regions, not just in the previously known Kirkwood gaps that are explained by the current planetary orbits,” Minton wrote in an email. In an editorial accompanying the paper, author Kevin Walsh added, “Qualitatively, it looks as if a snow plough were driven through the main asteroid belt, kicking out asteroids along the way and slowing to a stop at the inner edge of the belt.”

Walsh hails from the Observatoire de la Côte d’Azur in France. In his News and Views piece, he explains that the known Kirkwood gaps, discovered by Daniel Kirkwood in 1867, “correspond to the location of orbital resonances with Jupiter — that is, of orbits whose periods are integer ratios of Jupiter’s orbital period.” For example, if an asteroid orbited the Sun three times for every time Jupiter did, it would be in a 3:1 orbital resonance with the planet, he wrote. Objects in resonance with a giant planet have inherently unstable orbits, and are likely to be ejected from the solar system. When planets migrated, astronomers believe objects in resonance with them also shifted, affecting different parts of the asteroid belt at different times.

“Thus, if nothing has completely reshaped the asteroid belt since the planets settled into their current orbits, signatures of past planetary orbital migration may still remain,” Walsh wrote. And that’s exactly what Minton and Malhotra sought.

The asteroid belt easily gave up its secrets, showing the lingering evidence of planetary billiards on the inner edge of the asteroid belt and at the outer edge of each Kirkwood gap. The new finding, based on computer models, lends additional support to the theory that the giant planets — Jupiter, Saturn, Uranus and Neptune — formed twice as close to the sun as they are now and in a tighter configuration, and moved slowly outward.

“The orbit of Pluto and other Kuiper belt objects that are trapped in [orbits that resonate] with Neptune can be explained by the outward migration of Neptune,” Minton and Malhotra write in the new study. “The exchange of angular momentum between planetesimals and the four giant planets caused the orbital migration of the giant planets until the outer planetesimal disk was depleted.” Planetesimals are rocky and icy objects left over from planet formation.

“As Jupiter and Saturn migrated,” the authors continue, they wreaked havoc on the young asteroid belt, “exciting asteroids into terrestrial planet-crossing orbits, thereby greatly depleting the asteroid belt population and perhaps also causing a late heavy bombardment in the inner Solar System.”

The late heavy bombardment is proposed to have occurred about 3.9 billion years ago, or 600 million years after the birth of the Solar System, and it’s believed to account for many of the Moon’s oldest craters. Walsh said a reasonable next step, to corroborate the theory about the newly described clearings in the asteroid belt, is to link them chronologically with the bombardment.

LEAD PHOTO CAPTION: Artist’s depiction of the asteroid belt between Mars and Jupiter. Credit: David Minton and Renu Malhotra

Source: Nature

December 18, 2008December 24, 2015 by Nancy Atkinson

Jupiter’s Moon Plays Hide-and-Seek with Hubble

Ganymede is about to hide behind Jupiter. Credit: NASA, ESA, and E. Karkoschka (University of Arizona)

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NASA’s Hubble Space Telescope has caught Jupiter’s moon Ganymede playing a game of hide-and-seek. In this crisp Hubble image, Ganymede is shown just before it hides behind the giant planet. Images like this one are not only gorgeous and enjoyable to look at, but are also useful for studying Jupiter’s upper atmosphere. As Ganymede passes behind the giant planet, it reflects sunlight, which then passes through Jupiter’s atmosphere. Imprinted on that light is information about the gas giant’s atmosphere, which yields clues about the properties of Jupiter’s high-altitude haze above the cloud tops. And because Hubble’s view is so sharp, we can learn more about Ganymede as well. Visible are several features on the moon’s surface, most notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from the crater. Tros and its ray system are roughly the width of Arizona. Hubble has amazing eyesight!

And there’s a movie, too!

More about Ganymede and Jupiter…

Composed of rock and ice, Ganymede is the largest moon in our solar system. It is even larger than the planet Mercury. But Ganymede looks like a dirty snowball next to Jupiter, the largest planet in our solar system. Jupiter is so big that only part of its Southern Hemisphere can be seen in this image.
Ganymede completes an orbit around Jupiter every seven days. Because Ganymede’s orbit is tilted nearly edge-on to Earth, it routinely can be seen passing in front of and disappearing behind its giant host, only to reemerge later.

The image also shows Jupiter’s Great Red Spot, the large eye-shaped feature at upper left. A storm the size of two Earths, the Great Red Spot has been raging for more than 300 years. Hubble’s sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian atmosphere as well as various other storms and vortices.

This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to natural colors.

Source: Hubblesite

November 26, 2008December 24, 2015 by Nancy Atkinson

Jupiter Could Have Earth-like Rocky Core

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Jupiter has a rocky core that is more than twice as large as previously thought, according to computer calculations by a geophysicist who simulated conditions inside the planet on the scale of individual hydrogen and helium atoms. “Our simulations show there is a big rocky object in the center surrounded by an ice layer and hardly any ice elsewhere in the planet,” said Burkhard Militzer from University of California, Berkeley. “This is a very different result for the interior structure of Jupiter than other recent models, which predict a relatively small or hardly any core and a mixture of ices throughout the atmosphere.” A comparison of this model with the planet’s known mass, radius, surface temperature, gravity and equatorial bulge implies that Jupiter’s core is an Earth-like rock 14 to 18 times the mass of Earth, or about one-twentieth of Jupiter’s total mass, Militzer said. Previous models predicted a much smaller core of only 7 Earth masses, or no core at all.

The simulation suggests that the core is made of layers of metals, rocks and ices of methane, ammonia and water, while above it is an atmosphere of mostly hydrogen and helium. At the center of the rocky core is probably a metallic ball of iron and nickel, just like Earth’s core.

“Basically, Jupiter’s interior resembles that of Saturn, with a Neptune or Uranus at the center,” he said. Neptune and Uranus have been called “ice giants” because they also appear to have a rocky core surrounded by icy hydrogen and helium, but without the gas envelope of Jupiter and Saturn.

“This new calculation by Burkhard removes a lot of the old uncertainties of the 19-year-old model we have had until now,” said coauthor William B. Hubbard from the University of Arizona. “The new thermodynamic model is a more precise physical description of what’s going on inside Jupiter.”

The large, rocky core implies that as Jupiter and other giant gas planets formed 4.5 billion years ago, they grew through the collision of small rocks that formed cores that captured a huge atmosphere of hydrogen and helium.

“According to the core accretion model, as the original planetary nebula cooled, planetesimals collided and stuck together in a runaway effect that formed planet cores,” Militzer said. “If true, this implies that the planets have large cores, which is what the simulation predicts. It is more difficult to make a planet with a small core.”

In order to match the observed gravity of Jupiter, Militzer’s simulation also predicts that different parts of Jupiter’s interior rotate at different rates. Jupiter can be thought of as a series of concentric cylinders rotating around the planet’s spin axis, with the outer cylinders – the equatorial regions – rotating faster than the inner cylinders. This is identical to the sun’s rotation, Militzer said.
The researchers say their model matches up well with data from the Galileo spacecraft, which orbited Jupiter from 1995 -2003.

Militzer plans to use the new model to simulate other planets’ interiors, and to investigate the implications for the formation of planets outside our solar system. Future data from NASA’s Juno mission, to be launched in 2011 and orbit Jupiter by 2016 to measure the planet’s magnetic field and gravity, will provide a check on Militzer’s predictions.

Source: UC Berkeley