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Comets Are More Related to One Another Than Previously Thought

Many of them have similar chemical compositions

Jul 12, 2007 13:02 GMT  ·  By
Observations of the SW 3 comet, above, suggest that comets may have less diverse chemical compositions than thought.
   Observations of the SW 3 comet, above, suggest that comets may have less diverse chemical compositions than thought.

Each new piece of a comet brings scientists closer to understanding some of the most important events in the Universe and a recent analysis indicates that many comets may be related to one another, even more than previously thought.

Comets are celestial bodies that orbit stars like our Sun and are well known for their "tails" produced by the effects of solar radiation upon the comet's nucleus. Most of them are made of dust, rock and ice and have constantly changing orbits, even though they make constant appearances in our solar system.

Neil Dello Russo of Johns Hopkins University Applied Physics Lab in Maryland analyzed two fragments of the nucleus of the SW3 comet, which landed on Earth and found out that they displayed a more consistent mix of chemicals than previously anticipated.

This contradicts some assumptions about these space travelers and could provide new insight on the formation and evolution of our solar system, believed to have originated from a giant cloud of gas and dust some 4.5 billion years ago.

Russo found that the two fragments are more homogeneous than expected, but this does not completely invalidate the belief that there is a "great compositional diversity in comets throughout the population," he explained.

The results of the study indicate that the area in space where a comet is born must have a uniform array of chemicals, so that the comets exhibit more of the same ingredients, meaning that materials in the outer solar nebula, where comets form, are not as mixed as previously believed.

However, such a limited sampling is not decisive in formulating definitive conclusions about the comet nursery, so more comets sharing the same origin should be analyzed in order to fully understand their formation processes.

"For comet researchers," said Walter Harris, a planetary scientist at the University of California, Davis, "it's a lot like trying to understand how people are made and develop by looking only at a few students in kindergarten-and [then] some residents of a retirement home."