May 4, 2018
A University of Oklahoma astrophysics team explains why the growth of Mars was stunted by an orbital instability among the outer solar system’s giant planets in a new study on the evolution of the young solar system. The OU study builds on the widely-accepted Nice Model, which invokes a planetary instability to explain many peculiar observed aspects of the outer solar system. An OU model used computer simulations to show how planet accretion (growth) is halted by the outer solar system instability. Without it, Mars possibly could have become a larger, habitable planet like Earth. “This study offers a simple and more elegant solution for why Mars is small, barren and uninhabitable,” said Matthew S. Clement, OU graduate student in the Homer L. Dodge Department of Physics and Astronomy, OU College of Arts and Sciences.
May 10, 2018
For centuries, astronomers and scientists have sought to understand how our Solar System came to be. Since that time, two theories have become commonly-accepted that explain how it formed and evolved over time. These are the Nebular Hypothesis and the Nice Model, respectively. Whereas the former contends that the Sun and planets formed from a large cloud of dust and gas, the latter maintains the giant planets have migrated since their formation. This is what has led to the Solar System as we know it today. However, an enduring mystery about these theories is how Mars came to be the way it is. Why, for example, is it significantly smaller than Earth and inhospitable to life as we know it when all indications show that it should be comparable in size? According to a new study by an international team of scientists, the migration of the giant planets could have been what made the difference. As Matt Clement, a graduate student in the HL Dodge Department of Physics and Astronomy at the University of Oklahoma and the lead author on the paper, explained to Universe Today via email: “In the model, the giant planets (Jupiter, Saturn, Uranus and Neptune) originally formed much closer to the Sun. In order to reach their current orbital locations, the entire solar system undergoes a period of orbital instability. During this unstable period, the size and the shape of the giant planet’s orbits change rapidly.” For the sake of their study, which was recently published in the scientific journal Icarus under the title “Mars Growth Stunted by an Early Giant Planet Instability“, the team expanded on the Nice Model. Through a series of dynamical simulations, they attempted to show how, during the early Solar System, the growth of Mars was halted thanks to the orbital instabilities of the giant planets.