X-Nico

5D/Brorsen

The next serious search was started by Brian Marsden, who believed the comet had faded out of existence, but computed the orbit for a very favorable 1973 apparition.

Comet White–Ortiz–Bolelli

The comet's sudden appearance very close to the sun and rapid subsequent decline in brightness both pointed to it being a sungrazing comet, and calculations of its orbit by Brian Marsden backed this suggestion.

Kreutz Sungrazers

A study by Brian Marsden in 1967 was the first attempt to trace back the orbital history of the group to identify the progenitor comet.

Planets beyond Neptune

Noted Planet X sceptic Brian Marsden of Harvard University's Minor Planet Center pointed out that these discrepancies were a hundred times smaller than those noticed by Le Verrier, and could easily be due to observational error.

see also