No. 46: Jul-Aug 1986
"Halley's comet is coated with organic molecules. Two astronomers working with the Anglo-Australian Telescope, David Allen and Dayal Wickramasinghe, have found strong evidence in an infrared spectrum of the comet, taken two weeks ago. The spectrum, spanning the wavelengths 2-4 micrometres, shows a prominent feature centred at 3.4 micrometres which the two astronomers attribute to emission by carbon-hydrogen bonds in a solid."
Chandra Wickramasinghe (Dayal's brother) states that the emissivity of Halley's comet matches exactly the emissivity of bacteria as observed in the laboratory. This observation supports the Hoyle-Wickramasinghe suggestion that comets transport life forms around the universe. Of course, more conservative scientists contend that rather complex organic molecules can be synthesized in space abiogenically. These molecules might account for the observations.
(Chown, Marcus; "Organics or Organisms in Halley's Nucleus," New Scientist, p. 23, April 17, 1986.)
Comment. This article seems to be accompanied by a bit of scientific revisionism. In response to this discovery, one English scientist remarked that these results, "...only confirm what everyone has always suspected." Now, it is true that comets have long been termed "dirty snowballs" but until very recently no one has maintained that comets are covered with dark, organic sludge.
Reference. In category ACO23 in our catalog The Sun and Solar System Debris, we discuss in depth the blackness of cometary nuclei. For more information on this book, visit: here.