LONDON: Our Solar System is a relatively quiet place, which it ought to be after some 4.5 billion years. While the early days saw a flurry of violent activity, with collisions, gravitational interactions and even ejections, things have settled down an awful lot. In the inner Solar System, the four rocky planets orbit peacefully, undisturbed by one another. Beyond them, thousands of smaller, rocky bodies pass by in the asteroid belt. Out a little farther, the four gas giants — themselves failed stars — host their own complex planetary systems with moons of their own, while the Kuiper Belt and Oort Cloud lie even beyond that.
But every so often, a Kuiper Belt object wanders too close to Neptune, or a passing encounter with a star or rogue planet perturbs the Oort Cloud, or one of those outer, icy bodies passes too close to another. When this happens, there’s a reasonable probability that one of those distant, lonely worlds will change its trajectory and pass through the inner Solar System.
And when it nears us, passing interior to the orbit of Jupiter, it begins to heat up.
Tails begin to develop, and debris flies off of these bodies, creating the phenomenon we know as a comet. While we normally think of comets as stable, recurring phenomena — like Halley’s Comet, which returns every 76 years — the reality is a lot more complex. As comets make their periodic trips through the inner Solar System, they often pass by planets and/or the Sun relatively closely, and as such, have their orbits gravitationally influenced by these bodies.
