16P/Brooks

Lore & Background

William Robert Brooks discovered 16P/Brooks on 7 July 1889 but initially failed to note any motion; he confirmed the discovery the next morning after seeing the comet had moved north. On 1 August 1889, Edward Emerson Barnard found two fragments, labeled B and C, located 1 and 4.5 arc minutes away. The following day, Barnard observed another four or five fragments, but these were no longer visible the next day. On 4 August, he spotted two more objects, labeled D and E; E disappeared by the next night, and D was gone within a week. Fragment B grew large and faint around mid-month, finally vanishing at the beginning of September, while fragment C survived until mid-November 1889. The apparition ended on 13 January 1891. After this discovery apparition, the comet has always been over two magnitudes fainter.

The comet's breakup is believed to have been caused by its passage within Jupiter's Roche limit around 20 July 1886, when it spent two days within the orbit of Io. This very close approach to Jupiter resulted in the previous perihelion distance becoming the new aphelion distance. On 31 December 2016, the comet passed 0.333 AU from Jupiter, and it is predicted to pass about 0.26 AU from Jupiter on 5 July 2053 ± 3 days.

Reader's Guide

16P/Brooks holds significance as a well-documented example of cometary fragmentation following a close encounter with Jupiter. The detailed observations by Edward Emerson Barnard in 1889, capturing multiple fragments that appeared and faded over weeks, provide a rare historical record of a comet breaking apart. The comet's earlier disruption in 1886, attributed to passing within Jupiter's Roche limit, links its behavior to gravitational tidal forces. The fact that after its discovery apparition the comet has always been over two magnitudes fainter suggests that the fragmentation permanently altered its brightness. The comet's orbital evolution—where its previous perihelion distance became its new aphelion distance after the 1886 Jupiter approach—illustrates the dramatic gravitational reshaping of comet orbits by Jupiter. Future close approaches to Jupiter in 2016 and predicted for 2053 continue to make 16P/Brooks an object of interest for studying the long-term dynamics of Jupiter-family comets.