Many planetary systems are carefully balanced

Science News : The planets in our solar system are delicately arranged, according to astronomers. If a new planet were suddenly introduced, the additional gravitational pull would result in collisions and orbital ejections. Now that significant planetary systems have been discovered around other stars, astronomers are trying to determine whether those systems are similarly delicate. To that end, Julia Fang and Jean-Luc Margot of UCLA created millions of simulations of three- and four-planet solar systems, based on the arrangements of those that have been discovered by the Kepler space telescope. The average spacing of the simulated planets was very similar to that of the planets in our solar system. When Fang and Margot then introduced a new planet to each of the simulated systems, they found that at least one-third of the three-planet systems and nearly one-half of the four-planet systems became catastrophically unstable. Although the researchers caution that Keplerâs observations allow for some variations in planetary arrangements, they believe that balanced systems such as our own are common.