Chemical Factories Smaller than a Snowflake

In the warmer dust clouds (whose temperature is about 60 degrees above absolute zero, or minus 213 degrees Centigrade), the silicate grains are on the order of 1/100th of a micron in size (recall that one micron is a thousandth of a millimeter), whereas in very cold dust clouds (20 degrees above absolute zero, or minus 253 degrees Centigrade), the sizes are typically 1/10th of one micron, so they are minute indeed. A comparison may be helpful.

An ordinary snowfl ake — one of billions which may gently drift downward during winter — is 25 000 times larger — snowfl akes are typically of the order of 2500 microns across. A snow-fl ake is a veritable immensity compared to one grain of cold cosmic dust. Furthermore, the nucleus at the center of a snowfl ake measures one micron; the aerosols in the atmosphere around which a snowfl ake crystallizes measures 1/10th of a micron. Cold grains in dusty Shrouds of the Night, 1/10th of a micron in size, are truly like aerosols — the mists of a fog.


Chemical Factory Molecular Cloud Dust Cloud Absolute Zero Bright Star 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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© Springer Science+Business Media, LLC 2008

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