Depicts: Comet Linear, C/1999 S4
Copyright: NASA, H. Weaver and P. Feldman (Johns Hopkins University), M. A'Hearn (University of Maryland), C. Arpigny (Liege University), M. Combi (University of Michigan), M. Festou (Observatoire Midi-Pyrenees), and G.-P. Tozzi (Arcetri Observatory)
These three photographs taken with the Hubble Space Telescope chronicle a violent outburst in the life of comet LINEAR, also known as C/1999 S4. The orbiting observatory's Space Telescope Imaging Spectrograph tracked the streaking
comet for two days, July 5 to 7, capturing a dramatic leap in its brightness [left image];
followed by seeing a wave of newly created dust from the outburst flowing into the coma,
a shell of dust surrounding the core [middle image]; and culminating in the discovery of a
castoff chunk of material from the nucleus sailing along its tail [the bright dot trailing behind
the comet in the picture at right]. The white region represents the brightest part of the coma.
The nucleus cannot be seen in these images because it is about a mile or so across, which
is too small for the Hubble telescope to see.
Last Update: 1 September 2019