Halley's Confounding Fireworks

Abstract

The intensive worldwide campaign of observations of Halley's Comet repeatedly yielded data, particularly imagery, of sudden outbursts from the Comet. IUE data for Dec. 24, 1985 showed a brightness increase in the central coma by a factor of 2-3 over a 1-2 day period, followed shortly thereafter by spectra indicating a surge of ionized CO2 150,000 km down the tail. Other data of similar phenomena indicated that much of the comet dust and gas escaped from limited areas. Subsequent brightness measurements by numerous researchers indicated a rotation period of 2.2 days, although evidence supporting either a rotation or a nutation period of 7.4 days was also found.