These are the most frequently used words in this book.
1996
1997
across
active
activity
another
approach
asteroid
astronomers
away
belt
bright
came
change
close
cloud
coma
come
comet
days
deep
discovered
discovery
distance
during
dust
earth
enough
even
far
few
first
found
gas
great
halley
however
hyakutake
ice
impact
jets
km
kuiper
large
less
long
march
may
miles
million
mission
moon
nasa
near
new
now
nucleus
object
observations
observatory
observers
orbit
part
particles
people
perihelion
planets
point
probably
public
scientists
second
see
seen
several
show
since
size
sky
small
solar
space
spacecraft
star
still
study
sun
surface
system
tail
telescope
time
two
view
visible
water
wind
world
years
yet