ISON NEWS FLASH: 07:00 UT. 26th Nov. As the latest Jet Propulsion Laboratory info says- ISON is not leaving us forever. It will come back again. After 581480.34 years. Now its orbit is being considered as a long long ellipse with its eccentricity as .9999982136165803.But yes, scientists are still not sure on this. calculations are going on.