Water Fact File for Comets

The Bottom Line:

Just Water...

 

Findings from Dr Kotwicki's 1991 Paper:

Every 76 years during the past 200 000 years a black object, now peanut shaped and 15 km long, ventures near the Sun, exhibiting on most occasions a fabulous tail by losing some 1% of its mass during each rendezvous. Comet Halley is the best known, but tens of other comets are observed each year, implying both a large quantity and continuous supply.

Where do comets come from? Aristotle asserted that they form in the atmosphere, Hevelius believed that they originated in the Solar System and Kepler surmised that they form between the stars. Our dilemma is: are they a by-product of the formation of the Solar System or do they fly freely throughout the Universe, contributing to the so-called "missing matter"? Do they initiate the birth of stars in giant molecular clouds that have a mass exceeding a million times the mass of our Sun?

The current wisdom is that 1011 comets (a hundred billion is a favoured number in astronomy, meaning "many")  circumnavigate the Sun in a static "Oort" cloud (Oort, 1950) stretching halfway to the nearest star. The gross mass is  guesstimated to be between 0.1 and five Earth's masses: some scientists speculate that it may exceed the mass of Jupiter. New information put rather useful boundaries on our creativity: Anderson and Standish (1986) analysing Pioneer 10 data limit the suggested mass of any hypothetical belt of comets immediately beyond Neptune to less than five Earth masses.

Nevertheless, such a simplified view faces many challenges (Theokas, 1988, Bailey, 1989). The spiral arms of our Galaxy may be full of cometary material, and clusters of comets captured by our Sun from time to time. However, evidence on the origin of comets is scarce, as comets trapped in the inner Solar System "forget" the direction from which they came. As a lack of sampling material (to determine the deuterium to hydrogen ratio and hence the origin of a comet) allows for too  many speculations, picking up a sample from a comet has currently a high priority. In July 1990 the European space probe Giotto that swept past the eye of the Halley's Comet in 1986 was successfully redirected to fly within 965 km of comet  Grigg-Skjelierup in 1992. The Comet Rendezvous and Flyby (CRAF) project will be launched by NASA in 1995 with a task of firing a penetrator into the crust of a comet.

 

Latest Findings about Water on Comets:

 

 

Comet
COMETS
THE PLANETS
Saturn
Tethys
Dione
Enceladus
Rhea
Titan
Mimas
Iapetus
Other
Uranus
Ariel
Miranda
Oberon
Umbriel
Titania
Asteroids
Mars
Phobos and Deimos
Luna
Mercury
Venus
Earth
Neptune
Triton
Nereid
Charon
Planet X
Comets
Water in the Universe
Water in the Universe

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