The Journey of Flight.pdf - Valkyrie Cadet

theorize that Kleopatra is the remnant of an incredibly violent collision between two asteroids that did
not completely shatter and disperse all the fragments. Radar observations indicated the surface of the
asteroid is porous and loosely consolidated, much like the surface of Earth’s Moon. Its interior
arrangement and components are unknown. However, scientists believe its collision history to be
extremely unusual.
Comets
A comet is a small, irregularly shaped body whose tiny nucleus is composed of water, ice, rock and
frozen gases. Comets travel in highly elliptical orbits that take them very close to the Sun and swing
them into deep space, often beyond the orbit of the planet Pluto. Comet structures are diverse, but all
develop a coma (diffuse material surrounding the nucleus) that usually grows in size and brightness as
the comet approaches the Sun. Usually a small, bright nucleus will be visible in the middle of the
coma; these two structures (the nucleus and the coma) form the head of the comet.
As a comet moves closer to the Sun, it develops an enormous tail that can extend for millions of
miles from the head, away from the Sun. Far from the Sun, the nucleus is cold and its material is
frozen solid. It is this state that leads to comets being referred to as “dirty snowballs” since more than
half of the material composing the comet is ice. But as the comet approaches the Sun, the surface of
the nucleus begins to warm and the volatiles evaporate.
The evaporated molecules boil off, carrying small solid particles with them. This is what forms the
comet’s coma of gas and dust. This cloud of dust and gas spreads out from the nucleus and reflects the
sunlight. Thus a previously unnoticed, tiny speck suddenly becomes visible. As it continues to approach
the Sun, the stream of particles and radiation from the Sun sweep the gas and dust away from
the nucleus, forming a hazy head (the coma) and sometimes a tail as well. Some of the largest comets
have had tails 100 million miles long—more than the distance from the Sun to the Earth.
Each time a comet visits the Sun, it loses some of its volatiles. Eventually, it becomes just another
rocky object in the solar system; therefore, comets are said to be short-lived, cosmologically speaking.
Many scientists believe that some asteroids are comet nuclei that have lost all of their volatiles.
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