Cheapest vacation packages for Furthermore, a short-period comet is capable of becoming a striking object in the night sky if it makes a very close pass by Earth e.g., Comet Lexell in June/July of In addition, a number of astronomers believe that many short-period comets which in the modern era have a weak magnitude were probably brighter a few millennia ago. It is sometimes suggested that a given comet may have been brighter in the past by magnitude per millennium, although this is not a reliable measure. However, we do well to remember that virtually all the great historical comets, with the notable exception of Halley’s Comet, have been long-period comets that had made relatively few passes into the inner solar system and hence were still loaded with volatiles. It is long-period comets whose closest approaches to the Sun are within the orbit of Mercury at its farthest, just under half the Earth-Sun distance that are most likely to become bright, large, and long, and hence may put on a compelling celestial display. The fact that the Star of Bethlehem was visible for so long reveals that it was intrinsically extremely bright and indeed very large like Hale-Bopp in and Sarabat in meaning that it was a long-period comet. Cheapest vacation packages 2016.