These are the most frequently used words in this book.
age
aliens
almost
always
american
another
astronomer
atmosphere
book
called
came
carl
colleagues
contact
cosmos
day
down
druyan
during
early
earth
even
example
extraterrestrial
far
father
few
first
friend
get
good
great
harvard
high
human
ideas
kind
know
kuiper
later
life
little
long
man
mars
martian
may
might
moon
muller
new
now
nuclear
old
once
organic
own
paper
people
perhaps
planet
question
rachel
really
recalls
research
right
sagan
say
science
scientific
scientists
see
show
solar
space
stars
still
student
system
television
theory
thing
think
thought
time
told
two
ufo
university
urey
venus
war
work
world
wrote
years
yet
york
young