"We refer to Jupiter's path as the Grand Tack, because the big theme in this work is Jupiter migrating toward the sun and then stopping, turning around, and migrating back outward," says the paper's first author, Kevin Walsh of the Southwest Research Institute in Boulder, Colo. "This change in direction is like the course that a sailboat takes when it tacks around a buoy."
According to the new model, Jupiter formed in a region of space about three-and-a-half times as far from the sun as Earth is (3.5 astronomical units). Because a huge amount of gas still swirled around the sun back then, the giant planet got caught in the currents of flowing gas and started to get pulled toward the sun. Jupiter spiraled slowly inward until it settled at a distance of about 1.5 astronomical units—about where Mars is now. (Mars was not there yet.)
"We theorize that Jupiter stopped migrating toward the sun because of Saturn," says Avi Mandell, a planetary scientist at NASA Goddard and a co-author on the paper. The other co-authors are Alessandro Morbidelli at the Observatoire de la Cote d'Azur in Nice, France; Sean Raymond at the Observatoire de Bordeaux in France; and David O'Brien at the Planetary Science Institute in Tucson, Ariz.
Like Jupiter, Saturn got drawn toward the sun shortly after it formed, and the model holds that once the two massive planets came close enough to each other, their fates became permanently linked. Gradually, all the gas in between the two planets got expelled, bringing their sun-bound death spiral to a halt and eventually reversing the direction of their motion. The two planets journeyed outward together until Jupiter reached its current position at 5.2 astronomical units and Saturn came to rest at about 7 astronomical units. (Later, other forces pushed Saturn out to 9.5 astronomical units, where it is today.)
The effects of these movements, which took hundreds of thousands to millions of years, were extraordinary.
Jupiter's Do-Si-Do
"Jupiter migrating in and then all the way back out again can solve the long-standing mystery of why the asteroid belt is made up of both dry, rocky objects and icy objects," Mandell says.
Astronomers think that the asteroid belt exists because Jupiter's gravity prevented the rocky material there from coming together to form a planet; instead, the zone remained a loose collection of objects. Some scientists previously considered the possibility that Jupiter could have moved close to the sun at some point, but this presented a major problem: Jupiter was expected to scatter the material in the asteroid belt so much that the belt would no longer exist.
"For a long time, that idea limited what we imagined Jupiter could have done," Walsh notes.
Rather than having Jupiter destroy the asteroid belt as it moved toward the sun, the Grand Tack model has Jupiter perturbing the objects and pushing the whole zone farther out. "Jupiter's migration process was slow," explains Mandell, "so when it neared the asteroid belt, it was not a violent collision but more of a do-si-do, with Jupiter deflecting the objects and essentially switching places with the asteroid belt."
In the same way, as Jupiter moved away from the sun, the planet nudged the asteroid belt back inward and into its familiar location between the modern orbits of Mars and Jupiter. And because Jupiter traveled much farther out than it had been before, it reached the region of space where icy objects are found. The massive planet deflected some of these icy objects toward the sun and into the asteroid belt.
"The end result is that the asteroid belt has rocky objects from the inner solar system and icy objects from the outer solar system," says Walsh. "Our model puts the right material in the right places, for what we see in the asteroid belt today."
Poor Little Mars
The time that Jupiter spent in the inner solar system had another major effect: its presence made Mars smaller than it otherwise would have been. "Why Mars is so small has been the unsolvable problem in the formation of our solar system," says Mandell. "It was the team's initial motivation for developing a new model of the formation of the solar system."
Because Mars formed farther out than Venus and Earth, it had more raw materials to draw on and should be larger than Venus and Earth. Instead, it's smaller. "For planetary scientists, this never made sense," Mandell adds.
But if, as the Grand Tack model suggests, Jupiter spent some time parked in the inner solar system, it would have scattered some material available for making planets. Much of the material past about 1 astronomical unit would have been dispersed, leaving poor Mars out at 1.5 astronomical units with slim pickings. Earth and Venus, however, would have formed in the region richest in planet-making material.
"With the Grand Tack model, we actually set out to explain the formation of a small Mars, and in doing so, we had to account for the asteroid belt," says Walsh. "To our surprise, the model's explanation of the asteroid belt became one of the nicest results and helps us understand that region better than we did before."
Another bonus is that the new model puts Jupiter, Saturn, and the other giant planets in positions that fit very well with the "Nice model," a relatively new theory that explains the movements of these large planets later in the solar system's history.
The Grand Tack also makes our solar system very much like the other planetary systems that have been found so far. In many of those cases, enormous gas-giant planets called "hot Jupiters" sit extremely close to their host stars, much closer than Mercury is to the sun. For planetary scientists, this newfound likeness is comforting.
"Knowing that our own planets moved around a lot in the past makes our solar system much more like our neighbors than we previously thought," says Walsh. "We're not an outlier anymore."
For more information visit http://www.nasa.gov/topics/solarsystem/features/young-jupiter.html
- Fermi Telescope Caps First Year With Glimpse of Space-Time [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Antarctic Airborne Science Mission Nears Mid-Point [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Awards Education Research Grants to Minority Universities [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- New Celestial Map Gives Directions for GPS [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Invites Reporters to Tranquility Node Ceremony at Kennedy [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Happy Halloween [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA's Fermi Telescope Detects Gamma-Ray From "Star Factories" in Other Galaxies [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Announces Advisory Council Chairs and Committee Structure [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA and X Prize Announce Winners of Lunar Lander Challenge [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- MESSENGER Spacecraft Reveals More Hidden Territory on Mercury [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Successful Flight Through Enceladus Plume [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Education Secretary Hosts DC Students for Talk with Space Station [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Operation Ice Bridge Studies Antarctic Sea Ice [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA West Point Welcomes Home One of Their Heroes [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Spitzer Observes a Chaotic Planetary System [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- X-38 Crew Return Vehicle Finds New Home [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Frost-Covered Phoenix Lander Seen in Winter Images [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Have some faith He is doing his best [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- The Cross [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Spring Bloom in New Zealand Waters [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Hubble image showcases star birth in M83, the Southern Pinwheel [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Take Me Out to the Ballpark - On Mars! [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Poisk Poised for Live NASA TV Space Station Docking [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Ceremony Reset for ESA Handover of Tranquility to NASA [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- NASA Reproduces a Building Block of Life in Laboratory [Last Updated On: November 8th, 2009] [Originally Added On: November 8th, 2009]
- Now Online: Aeronautics Goes E-Book [Last Updated On: December 12th, 2009] [Originally Added On: December 12th, 2009]
- Water on the Moon, Drought on Earth: NASA Experts Available for Radio And Podcast Interviews During Major Science Meeting [Last Updated On: December 12th, 2009] [Originally Added On: December 12th, 2009]
- Launch of NASA's Wise Spacecraft Delayed Until Dec. 14 [Last Updated On: December 12th, 2009] [Originally Added On: December 12th, 2009]
- Connecticut Students Set for Cosmic Conversation with Space Station Commander [Last Updated On: December 12th, 2009] [Originally Added On: December 12th, 2009]
- Magnetic Dance of Titan and Saturn To Be Main Attraction during Flyby [Last Updated On: December 12th, 2009] [Originally Added On: December 12th, 2009]
- Hubble's Deepest View of Universe Unveils Never-Before-Seen Galaxies [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Earth's Moon [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- How do you Make a Helicopter Safer to Fly? You Crash One. [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Physicist Earns Title as Kennedy's Best [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Hubble Unveils Never-Before-Seen Galaxies [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Saturn's Mysterious Hexagon Emerges from Winter Darkness [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Fermi Sees Brightest-Ever Blazar Flare [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Magnetic Power Revealed in Gamma-Ray Burst Jet [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Just 5 Questions: Aerosols [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Hometown Heroes 2009: Astronaut & Terrible Towel Return to Pittsburgh [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Garver Honors Four for Saving the Life of a Fifth at NASA Langley [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Administrator Bolden Speaks at AAIA-WIA Luncheon [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Best (Meteor) Shower of 2009 - No Towel Required [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- NASA Making Government More Accessible With Cutting-Edge Use Of New Media [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Scarce Water, Our Quiet Sun and Space Rocks Among NASA News Highlights at American Geophysical Union Meeting [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Press Credentials Deadlines Set for Next Space Shuttle Flight [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Reddish Dust and Ice Migration Darken Saturn's Moon Iapetus [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Galaxy Collision Switches on Black Hole [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- I’m watching the launch of NASA’s WISE spacecraft [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- SOFIA Aloft [Last Updated On: December 13th, 2009] [Originally Added On: December 13th, 2009]
- Guide to the International Space Station Laboratory Racks Interactive [Last Updated On: December 14th, 2009] [Originally Added On: December 14th, 2009]
- Freezing WISE's Hydrogen [Last Updated On: December 14th, 2009] [Originally Added On: December 14th, 2009]
- Local High School Wins Invention Challenge [Last Updated On: December 14th, 2009] [Originally Added On: December 14th, 2009]
- WISE Ready to Soar Into Space [Last Updated On: December 14th, 2009] [Originally Added On: December 14th, 2009]
- NASA Data Reveal Major Groundwater Loss in California's Heartland [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- NASA Looks for Safer Icing Forecast For Pilots [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- Challenges of Living and Working Aboard the Space Station: NASA Astronaut Nicole Stott Available for TV Interviews [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- NASA Astronaut, Food Scientist Available for Interviews about Holiday Feasts in Space [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- NASA Launches Web Site for Teenagers That Want More Class [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- A Unique Geography -- and Soot and Dust -- Conspire Against Himalayan Glaciers [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- New Study Turns Up the Heat on Soot's Role in Himalayan Warming [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- NASA's WISE Eye on the Universe Begins All-Sky Survey Mission [Last Updated On: December 15th, 2009] [Originally Added On: December 15th, 2009]
- NASA Offers Sound Clips for Radio, Online Newscasters [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- NASA Gets Up-Close Look at Far Corner of the Globe [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Orion Launch Abort System Attitude Control Motor Test-fired [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Hubble Finds Smallest Kuiper Belt Object Ever Seen [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- The Dark Side of Carbon [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- R97UYEA6HD8W [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- NASA's AIM Satellite and Models are Unlocking the Secrets of Mysterious "Night-Shining" Clouds [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Classroom Learning Takes Off with NASA-Funded Education Projects [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- NASA Buys Additional Space Shuttle Reusable Solid Rocket Motors [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Searching for New Vaccines and Studying Butterflies in Space; NASA Offers TV Interviews about Latest Space Station Science Research [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- NASA Partners with Saudi Arabia on Moon and Asteroid Research [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- New Results from a Terra-ific Decade in Orbit [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Deposits in Martian Trough Point to Complex Hydrological Past [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- NASA Outlines Recent Greenhouse Gas Research [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Unexpected Wheel-Test Results [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Solar Storms and Radiation Exposure on Commercial Flights [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Global Digital Elevation Model [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]
- Hubble's Festive View of a Grand Star-Forming Region [Last Updated On: December 17th, 2009] [Originally Added On: December 17th, 2009]