A comet's nucleus, or heart, is the solid chunk of something in
the center of its fuzzy coma. As it approaches the Sun, some of
its surface boils off and creates a long tail. But what IS
inside a comet's nucleus? Marshmallows? Chewy caramel? Nuts?
Here is what scientists have found out. Comets are part of the
solar system. They orbit the Sun, just as planets do, except a
comet usually has a very elongated orbit. Part of its orbit is
very, very far from the Sun and part is quite close to the Sun.
A comet's nucleus is like a dirty snowball made of ice. As the
comet gets closer to the Sun, some of the ice starts to melt and
boil off, along with particles of dust. These particles and
gases make a cloud around the nucleus, called a coma. The coma
is lit by the Sun. The sunlight also pushes this material into
the beautiful brightly lit tail of the comet. Scientists have
now had a look inside a comet's nucleus. On July 4, 2005, NASA's
Deep Impact spacecraft's "smart impactor" scooped out . . .
well, more like blaste