ISON Died a Customary Comet Death
Comet ISON was not unusual for breaking up and sputtering to a fiery end. That’s in comets’ nature.
Hopes for a big show by the advertised “comet of the century” came to a dismal end as Comet ISON broke up after its perihelion swing around the sun on November 28th. The announcement was a bit of a roller-coaster ride. Initial reports failed to see it re-emerge after its fiery plunge behind the sun, but then a broad, wedge-shaped tail appeared in SOHO images long enough to keep hope alive. It rapidly dimmed, however, leading astronomers to conclude it had been ripped apart into smaller fragments that quickly burned out.
Richard A. Kerr, writing for Science Magazine, said that comets often break up:
Comet ISON’s disintegration into a cloud of debris as it neared its closest approach to the sun on 28 November came as no surprise to astronomers. They knew the kilometer-size “dirty snowball” or nucleus at the heart of the comet had never been tested by the rigors of a passage through the inner solar system. And no icy comet nucleus was all that sturdily built eons ago during the formation of the planets…. Astronomers now believe that the sun’s searing heat and its wrenching tidal pull—stretching the nucleus like so much putty—did in the nucleus hours before its closest approach to the sun.
Heat and tidal stress are destructive processes. PhysOrg says Comet ISON lost three trillion tonnes of its mass per second as it rounded the sun. Kerr assumes that comets are dirty “snowballs,” borrowing the terminology of earlier astronomers who thought that they originated far away from the sun (wrong; see 1/25/08 and 9/09/08). What’s proven more interesting than the snow is the dirt. The Deep Impact (9/07/05) and Stardust (3/14/06, 12/18/06) missions surprised astronomers by showing evidence of minerals that required high temperatures to form (4/18/11, 7/29/11), 9/24/08).
Kerr assumes that comet nuclei were “built eons ago,” (albeit not “sturdily”), but no one has observed any solar system body accrete from dust or ice. What they do observe is bodies like comets blowing out material (like a comet tail, the geysers of Enceladus, or the volcanoes of Io), or breaking up, or both (5/10/06). Planetary scientists have had difficulty explaining the source of comets (e.g., 9/03/03, 10/05/03) and their longevity (e.g., 12/27/07).
As it is in the nature of comets to break up, it is in the nature of science reporters to use assumptions as a shield for ignorance. Kerr speaks glibly about “the formation of the planets.” OK, Mr. Kerr, how did they form? Using only the laws of physics, and no design, can you get small particles to form an Earth or a Jupiter? (See 6/23/11, 5/21/09, or for comets, 10/01/07). Do you have any observational evidence for your model? Remember, some dust disks around other stars were thought to be early solar systems, but were later re-interpreted to be remnants of planets breaking up (see 7/07/12).
We’ve reported many times about the short lifetimes of comets and how this poses problems for belief in billions of years. Search on “comets” on this page for examples, like “Comets are Cracking Up” (3/29/10) and the embedded links provided above.