These are the most frequently used words in another edition of this book.
actually
atoms
away
bang
between
big
billion
black
chapter
clusters
cosmic
dark
density
different
dimensions
distance
down
early
earth
effect
einstein
energy
enough
entire
even
everything
exist
expansion
far
few
first
force
form
formed
further
galaxies
gas
gravitational
gravity
helium
holes
however
hydrogen
indeed
itself
kind
large
larger
laws
less
life
light
mass
matter
may
might
million
must
new
now
nuclear
number
objects
orbit
own
particles
per
planets
present
protons
rather
scale
second
see
seem
should
small
smaller
solar
space
speed
stars
still
structure
sun
surface
system
telescopes
temperature
ten
theory
though
three
time
together
two
universe
value
world
years