Advanced computer simulations show that Jupiter was formed four times farther from the sun before wandering into the solar system and resting on its orbit.
Early theories suggested that giant gas planets are often very close to their host star. The new study published in the journal Astronomy & Astrophysics could prove that Jupiter may be an outlier.
A Wandering Planet
Researchers from Lund University in Sweden calculated how Jupiter landed on its current orbital path approximately 4.5 billion years ago. During this time, the gas giant was no bigger than Earth.
Based on their calculations, PhD student and lead author Simona Pirani said the young Jupiter originated from a location that is four times than its current distance to the sun. Other gas giants like Saturn and Neptune may have migrated the same way as Jupiter.
The inspiration for going deeper into its journey to the solar system was the asymmetry of the Trojan asteroids found in front of and behind Jupiter.
Two groups of Trojan asteroids adjacent to Jupiter differ in size. One group has 50 percent more asteroids than the other. Scientists believed that identifying the cause of the asymmetry will help them understand Jupiter's migration.
"This is the first time we have evidence that Jupiter was formed far from the sun and then migrated to its current path," Pirani said. "The evidence for the migration can be found in the Trojan asteroids that revolve near Jupiter."
Pirani's team reported that the migration took around 700,000 years, about 2 to 3 million years since Jupiter began its life. It followed a spiral-shaped movement in an increasingly narrow path toward the sun.
Forming The Trojan Asteroids
Computer simulations showed that Jupiter began capturing Trojan asteroids as a young planet without a gas body. Jupiter may have the same building blocks as those that can be found in the asteroids.
"The reason for the asymmetry is the relative drift between the migrating planet and the particles in the coorbital resonance," the authors said. "The capture happens during the growth of Jupiter's core and Trojan asteroids are afterwards carried along during the giant planet's migration to their final orbits."
The gravitational force from Jupiter's surrounding gas caused the migration itself.
Journey To Jupiter's Trojans
In October 2021, NASA will launch Lucy, the first space mission to study the Trojan asteroids. Scientists believe that these celestial bodies will provide vital clues on the formation of the outer planets as well as the origin of the solar system and organic life on Earth.
Lucy will complete a 12-year journey to a Main Belt asteroid and six Trojans. It will provide a closer look to the C-, P-, and D types of bodies in the swarms of asteroids. It is said that dark carbon compounds, water, and other volatile substances make up the asteroids.
