Why are giant extrasolar planets often found in elongated orbits?

In contrast to the planets in our solar system, which travel on nearly circular paths, many giant extrasolar planets with orbital periods longer than two weeks are found in elongated orbits.1

While the specific reasons for these orbital characteristics remain a subject of ongoing study, models of planetary formation suggest that giant planets often form at greater distances from their host stars and subsequently migrate inward. This migration is thought to occur as a result of gravitational interactions with the remnants of the circumstellar disks from which the planets originally accumulated. In some cases, gravitational interactions can also lead to planets being ejected from their solar systems entirely, resulting in a population of free-floating giant planets.1