小行星53351991

当达摩克里斯在1991年被罗伯特·H.·麦坎纳发现时，他发现它的轨道与过去已知的小行星都不一样。达摩克里斯的近日点在火星的轨道附近，而远日点在天王星的附近，他似乎是从外太阳系的圆轨道转换成椭圆轨道进入内太阳系。 邓肯·史提尔、杰拉尔德·汉恩、马克·贝利和 David Asher推导出动力学上长期演变的结果，发现一个可能成为越地小行星 (Earth-crosser asteroids)的好方法，并且在这样的轨道上经度过了四分之一的生命期。达摩克里斯在成为目前的状态之前，因为它的轨道高度倾斜，使它不会接近木星或土星，因而曾经有数万年是在稳定的轨道上运转。

有一些猜测认为在火星上也许可以看见达摩克里斯造成的天龙座流星雨。

5335 Damocles, provisional designation 1991 DA, is an astronomical centaur and the namesake of the damocloids, a group of minor planets which may be inactive nuclei of the Halley-type and long-period comets. It was discovered on 18 February 1991, by Australian astronomer Robert McNaught at Siding Spring Observatory in Australia. It is named after Damocles, a figure of Greek mythology.

Description

When Damocles was discovered, it was found to be on an orbit completely different from all others known. Damocles's orbit reached from inside the aphelion of Mars to as far as Uranus. It seemed to be in transition from a near-circular outer Solar System orbit to an eccentric orbit taking it to the inner Solar System. Duncan Steel, Gerhard Hahn, Mark Bailey, and David Asher carried out projections of its long-term dynamical evolution, and found a good probability that it will become an Earth-crosser asteroid, and may spend a quarter of its life in such an orbit. Damocles has a stable orbit for tens of thousands of years before and after the present, because its highly inclined orbit does not take it near Jupiter or Saturn.

There is some speculation that Damocles may have a meteor shower associated with it on Mars from the direction of Draco. The object has a Mars minimum orbit intersection distance (Mars MOID) of 0.057 AU (8,500,000 km; 5,300,000 mi) and a Uranus MOID of 0.3 AU (45,000,000 km; 28,000,000 mi).

As of 2019, Damocles is 19.6 AU from the Sun with an apparent magnitude of 26.3. It reached its furthest point from the Sun in 2011.

The adjectival form is Damoclean, /dæməˈkliːən/. The official naming citation was published by the Minor Planet Center on 1 September 1993 (M.P.C. 22508).