‘Fragile comets’ origins mystery

by David Catchpoole

^{Credit: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI)}

The ongoing and rapid breakup of comet 73P/Schwassmann–
Wachmann 3 is leaving evolutionary cosmologists puzzling over how such a ‘fragile’ body could have ever come together in the first place. (click for larger image)

We have many times reported (e.g. Comets—portents of doom or indicators of youth?, Creation 25(3):36–40, 2003; Sun decapitates comets, Creation 26(2):9; 2004) that the rapid rate of visible decay of comets (‘dirty snowballs’ of ice and dust) every time they pass the sun speaks of a young (i.e. only thousands of years old) universe. Avoiding that conclusion, cosmologists have suggested that comets originate from the ‘Oort cloud’ said to surround our solar system (or more recently, the ‘Kuiper Belt’ just past Neptune).

However, the Oort cloud and Kuiper Belt concepts are completely hypothetical. The Oort cloud has never been observed. There is a region called the Kuiper Belt, containing ‘Kuiper Belt Objects’ (KPOs), but its contents do not correlate with the type of region proposed by Dutch astronomer Gerald Kuiper in 1951 to solve the evolutionary dilemma of how to resupply short-period comets. Thus they are often called by the more objective term ‘trans-neptunian objects’ (TNOs) — see Kuiper Belt and this response to a critic. What’s more, given the relative fragility of comets, exactly how do evolutionary cosmologists propose that comets are formed?

This is precisely the problem that the ongoing breakup of Comet 73P/Schwassmann—
Wachmann 3 has brought into sharp focus. This comet passes the sun every 5.4 years and its continuing fragmentation has captured the attention of many space-watchers. This year telescopes showed that over 30 of the biggest fragments had themselves each split into several dozen smaller chunks 20 to 30 metres across. This prompted Casey Lisse of the Johns Hopkins Applied Physics Laboratory in Maryland, USA, to observe that the cores of comets ‘are as fragile as the meringue in lemon-meringue pie.’

Thus there remains a ‘great mystery’, according to Lisse. ‘How can a body as weak as meringue come together on a kilometre scale, then fall apart?’