Sunday, April 12, 2009


Eros is moon sized asteroid. However, the very first image of Eros from orbit, seems to show a linear track starting randomly on the asteroid’s surface, then climbing up the outside wall of a crater, running down the inside wall, ending at a 50-meter boulder near the crater center.Since that initial picture, dozens of additional trails, boulders, and trails ending in boulders have been found on the surface of Eros. Surprised planetary astronomers are now theorizing about boulders ejected from the interior of Eros during collision events.
To his considerable credit, planetary astronomer Andrew Cheng,presented evidence that Eros originated from “probably a planet-sized body that once broke up”. but that the current opinion of most astronomers is that it was Moon-sized or smaller. This evidence for a large parent body for Eros includes:
Geological layering, which could not have been created directly on the asteroid because its escape velocity is so low, and material from any impact big enough to create layers would therefore escape. Diversity of composition, showing major spectral differences over the surface, and even within single craters. Evidence of chemical differentiation, which implies near-total melting sometime in the past with consequent separation of heavy and light elements by gravitational sorting – things usually associated with planets. Solidness implied by the density, as contrasted with the sort of rubble pile expected for an object formed by repeated impacts.

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