LOST COMETS

Shannon News, 27 August 1926, Page 3

LOST COMETS

(BY J- A. LLuTD, F.R.A.S.) It is a strange tact that comets are sometimes lost. The latest instance is Ensor s Comet This was discovered- in 1925 and - was expected to be a prominent object in the northern heavens early m 1926. It seems however, to have disappeared. . t A well known comet ,which went astray is Biela’s Come:, discovered en 1826. Its path was calculated by the mathematicians and it was found ’ to have a period of 61 years. It was seen on its nekt return to the sun in 1832, missed in 1839, and seen again in 1846, when it seemed at first to be quite normal. But after a while it broke in two, the two half comets gradually separating from each other. The ' two parts were again seen in 1852, but this time the distance between them was much greater. The comet has never been ■ seen since, but in 1872, when the earth was crossing the path of the comet, a remarkable sl'.ower of shooting stars came from the of the heavens which would have been occupied by the comet if it had been visible. ' . Yet another example is Lexeli s Comet. This was discovered in 1770 by Messier Its path was calculated by Lexeli, who found that it should return every five years. But the comet was never seen afterwards, ’ although eagerly looked for. A comet discovered by Peters in 184 f was found to have a period of 13i years. It has never been seen since. Stephen’s Comet, found in 1846, and calculated to return every 40 yeara was not 'seen again. De Vico’s Comet, discovered in 1846, should have' returned in 1921, but the strictest watching failed to observe it. Why should comets get lost? There are two good reasons. First, a comet is simply atswarm of meteorite's moving in on orbit round the sun. The tail consists of waste gases from the head. This means that a copiet is continually wasting away and at every turn must get smaller. Halley’s. Comet is not nearly so spectacular now as it was in ancient times. Secondly, a comet may pass near one of the giant planets, Jupiter or Saturn, and so come under its gravitational influence. The result Is that the comet is thrown out of its course, and, Instead of returning to the sun, passes off into space, never to return.