Spotting exoplanets is very hard to do directly. The best bet is to find an indirect method, such as the amount of light they block from their host star, the gravitational lens they produce as they pass between us and another object, or the amount they pull their host star about. Another suggestion is to look for how they alter the distribution of debris in their version of the solar system. Round these parts, the outer debris ring is the Kuiper Edgeworth belt, and just like Saturn’s rings are shepherded by Saturn’s moons, so this belt is kept in line by the planet Neptune. Looking for well kept borders enables some idea that a planet may be available, but when looking at even earlier times in a solar system’s formation, the evidence of an outer planet’s influence can be even easier to spot.
NASA researchers have now modelled the effect of Neptune on the belt, going back to the earliest times in the solar system’s history. They find a well kept belt forms in around 15 million years. The researchers plan to extend their findings to researching the main asteroid belt as well as the capture of Trojan asteroids by gravitational sources associated with Jupiter. They will also investigate models of dusty rings seen in other planetary systems to see what information can be obtained. Further information and a video of the creation of our outer ring can be seen here.