Sir, - The current great comet, Hale Bopp, attracts understandably a lot of attention. On March 24th, you mentioned that the comet is not to return for another 4,400 years. This refers in fact to the orbital period - indeed well over 4,000 years - with which Hale Bopp was approaching our regions.
Due to the gravitational influence of the giant planet Jupiter, however, the comet's orbit is perturbed during the present passage and its period will be shortened to some 2,500 years. After that span of time, Hale Bopp will return to the solar surroundings. The attraction of Jupiter on comets was dramatically evident in summer 1994, when a series of cometary fragments plunged into its atmosphere, as many of your readers no doubt will recall. - Yours, etc,
Director,
Dunsink Observatory.