A fleck retrieved from a distant comet is reshaping our ideas of how and when comets formed.
- A particle retrieved from a comet is found to have formed near sun.
- Scientist suspect shock waves may be responsible for flinging particles to the outer solar system.
- Comets, believed to contain pristine remains of materials from which the solar system formed, turn out to be not so simple.
Scientists don't know how it got there, but after spending about 2 million years in the relative warmth of the inner solar system, a particle of matter was heaved out into the frigid nether-regions where it eventually became part of a comet.
The speck was among the samples returned from the comet Wild-2 (pronounced "Vilt-2") by NASA's Stardust science mission. It is the first of what scientists hope will be many particle lineages unraveled as analysis of the microscopic grains continues. Compiled, these stories may begin to shed light on how the solar system took shape.
Based on detailed chemical analysis, Jennifer Matzel, a researcher at Lawrence Livermore National Laboratory, and colleagues figured out that the particle, which measures about 5 microns -- about the width of a single human red blood cell -- spent a fair amount of time in the inner solar system before it was transported out beyond Neptune and became incorporated into the comet.