Question

does the comet have constant linear speed ?

Answer 1

Its not about constant linear speed they don't have linearly motion or in short rectilinear motion .. yeah they do have same speed .. that's makes us to know when they'll be arriving next time .. many catastrophic event might happen like escaping of giant stars or even something else which might affect the current gravitational equilibrium so it might happen the comet would have a new path to roam around or it might fade