Question

What are the conditions of interstellar space?

The interstellar medium is cold, dark, and very nearly empty. Its incredibly low density of molecules keeps it a near vacuum almost devoid of heat due to lack of molecular movement. Nevertheless, our region of the galaxy holds about 1 atom of gas per cubic centimeter of space, and about 25-50 solid particles per cubic kilometer of space. This means that of the little space occupied by matter in interstellar space, about 99% of it is gas while roughly 1% is cosmic dust. Cosmic dust usually consists of carbon or silicates, possibly frozen water, ammonia, and solid carbon dioxide. However, interstellar space is not evenly dense. Stretching across several light years (thousands of times more massive than our sun) are dark clouds of gaseous matter strewn across the universe. Many of these clouds have been observed to contain molecular hydrogen, water, carbon monoxide, ammonia and even organic molecules such as PAH’s. While the harsh conditions of interstellar space may be unlikely to support life, many scientists are currently investigating the possible connections between the organic compounds founds in these regions of space and the origin of life. For more information on the connection between life and interstellar space, see our Ames Astrochemistry website at http://web99.arc.nasa.gov/~astrochm/science.html
March 11, 2002