Asteroid belt mystery solved | COSMOS magazine.
One of the biggest surprises of the past 14 years of exoplanet discoveries is the extremely close orbits Gas Giants and Neptune-class planets are being found in. This has supported the once theoretical process of planet migration – when a planet increases or decreases its orbit in interaction with the planetesimal debris around it. Now migration is being used to predict where the natural space-junk is going to end-up and how long it will survive. Renu Maholtra and David Minton have simulated the migration of Jupiter and its effects on the Main Belt asteroids, discovering that a deadly spray of them was produced nearly 4 billion years ago. Fortunately for their theory this fits exactly what is known as the Late Heavy Bombardment.
The Solar System is a big place, but we’re huddled close to the Sun and we think we’re in the best bit. During the Great Migration that drew Jupiter inwards and flung Uranus and Neptune outwards, a multitude of small objects were propelled far from the Sun. Most numerous of these displaced icy planetesimals are the residents of the Edgeworth-Kuiper Belt and Opik-Oort Cloud. But, according to some models, there could be much larger objects amongst the flotsam and jetsam of Gas Giants jostling for stability. Alan Stern, former chief investigator of the New Horizons probe to Pluto, has opined that a thousand Pluto-like worlds, up to Mars-Earth in size, could be out there in the Far Dark Places. They might be easy to terraform than launching vessels off to other stars. Vast light-weight mirrors could provide them with heat-and-light from the distant Sun.