20D/Westphal

Lore & Background

The comet was originally discovered by German astronomer J. G. Westphal on July 24, 1852, from Göttingen, Germany. It was independently discovered by American astronomer Christian Heinrich Friedrich Peters on August 9, 1852, from Constantinople. During its initial apparition, the comet exhibited many fluctuations in intrinsic brightness and reached an apparent magnitude of around 4, while a dust tail was also observed. It was last observed about 120 days after perihelion.

The comet was recovered on September 27, 1913, by Pablo T. Delavan at the La Plata Astronomical Observatory, about 60 days before perihelion. However, the comet faded as it approached the Sun, losing its central condensation and the nucleus becoming elongated. Plates of the comet indicate that disintegration began on October 1, 1913, when the comet was reported to be visible with the naked eye using averted vision. It was last observed on November 26, 1913.

Predicted to return in 1976, the comet was never observed and is now considered a lost comet. Its orbital period of 61 years fits the classical definition of a Halley-type comet (20 years < period < 200 years).

Reader's Guide

20D/Westphal holds significance as a documented case of a periodic comet undergoing disintegration during an apparition. The 1913 observations, which recorded the loss of central condensation and elongation of the nucleus, provide a historical record of cometary breakup. The comet's failure to return as predicted in 1976, despite a well-established orbital period of 61 years, confirms its status as a lost comet. Its independent discovery by two astronomers in 1852 and its recovery by Delavan in 1913 illustrate the collaborative nature of early cometary astronomy. The comet's fluctuations in intrinsic brightness and the observation of a dust tail contribute to the understanding of Halley-type comets. The fact that it was last observed 112 years ago underscores the challenge of tracking comets with long orbital periods, especially those that have undergone structural changes. The comet's legacy is tied to its role as a cautionary example of cometary instability and the limitations of predicting returns for objects that may no longer exist as coherent bodies.

Did You Know?

• 20D/Westphal was independently discovered by two astronomers: J. G. Westphal on July 24, 1852, and Christian Heinrich Friedrich Peters on August 9, 1852.
• The comet disintegrated during its 1913 apparition, with plates indicating the breakup began on October 1, 1913.
• It was last observed on November 26, 1913, and has not been seen in 112 years.
• The comet was predicted to return in 1976 but was never observed, and is now considered a lost comet.