Comet dust is like green Hawai'i sand

This mid-infrared image shows Comet 9P/Tempel 1 after the Deep Impact collision. Carbon-rich dust from the comet surface is red, and silicate-rich fresh dust from underneath the comet surface is green.

Particles tossed up by NASA's Deep Impact strike on a comet in July consist largely of olivine -- green silicate crystals commonly found in volcanic material in Hawai'i.

The dust cloud that resulted when the NASA probe struck Comet 9P/Tempel 1 on July 4 was studied by telescopes on Mauna Kea, which measured how much dust was thrown up and what it is made of. Scientists said the dust is similar to the particles found on Hawai'i's green sand beaches but much smaller.

Comets contain material from a time near the formation of the solar system 4.6 billion years ago, and study of the dust provides researchers with a glimpse of the basic materials that formed the planets.