▪
naked
eye
limit
-
For
observers
in
very
dark
skies,
it
is
possible
to
see
stars
as
faint
as
6th
magnitude.
The
magnitude
system
is
a
ranking
system where first magnitude stars are the brightest. In light polluted skies where I live, we are lucky to see 3rd magnitude stars.
▪
nebula
-
In
the
classical
sense,
a
nebula
is
any
astronomical
object
that
is
not
a
pinpoint
of
light.
At
one
time,
this
definition
included
galaxies
other
than
our
own
Milky
Way,
and
clusters
of
stars.
Nowadays,
the
definition
is
limited
to
patch
of
light
caused
by
glowing
interstellar
gas
or
dust.
▪
neutron
star
-
A
condensed
remnant
of
an
exploded
massive
star,
no
bigger
than
a
few
kilometers
in
size.
Spinning
neutron
stars
are
what
we observe as pulsars.
index
index
▪
naked
eye
limit
-
For
observers
in
very
dark
skies,
it
is
possible
to
see
stars
as
faint
as
6th
magnitude.
The
magnitude
system
is
a
ranking
system
where
first
magnitude
stars
are
the
brightest.
In
light
polluted
skies
where
I
live,
we
are
lucky to see 3rd magnitude stars.
▪
nebula
-
In
the
classical
sense,
a
nebula
is
any
astronomical
object
that
is
not
a
pinpoint
of
light.
At
one
time,
this
definition
included
galaxies
other
than
our
own
Milky
Way,
and
clusters
of
stars.
Nowadays,
the
definition
is
limited
to
patch
of
light
caused
by
glowing interstellar gas or dust.
▪
neutron
star
-
A
condensed
remnant
of
an
exploded
massive
star,
no
bigger
than
a
few
kilometers
in
size.
Spinning
neutron
stars
are
what
we
observe
as
pulsars.
