Re: Do comets really contain any frozen water?

Hi Marilyn,

Yes, there is frozen water in comets. Comets are mostly frozen water. When comets start out, far from the Sun, they are made up mostly of frozen water, perhaps some frozen methane, and small amounts of other materials like dust, ammonia, CO2, CO, and so on. As a comet approaches the Sun, it warms up and some of the frozen gases melt. This gas quickly escapes, forming a huge cloud around the comet, and carrying with it bits of other materials. It's this cloud of gas and dust that we see when looking at a comet in the sky. The solid part of the comet is called the nucleus, and it is much harder to see because it is so small compared to the cloud of gas streaming out from it.

You can find more about comets at http://www.il-st-acad-sci.org/planets/comets3.html and http://amazing-space.stsci.edu/resources/explorations/comets/teacher/scientificbackground.html and there's a description of how to build your own comet at http://www.solarviews.com/eng/edu/comets.htm . You might also want to read about NASA's Deep Impact mission, which is about to give us a lot more information about comets, when it smashes into one on July 4, 2005. Take a look at http://deepimpact.jpl.nasa.gov for more info.