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**Edwin Powell Hubble** was an American astronomer who played a cru...
#### From a Static to an Expanding Universe Up until 1929, the vas...
The period/luminosity relation for Cepheid variables on which Hubbl...
Hubble uses standard candles in order to determine the relative dis...
This table shows Hubble's observations. It is important to notice t...
From his results Hubble notices that there seems to be a correlatio...
This table shows Hubble's measurements. Here too it is important to...
### Age of the Universe from Hubble constant: One can easily fin...
### Hubble Parameter: This plot is Hubble's most important observa...
The fact that we see other galaxies moving away from us does not im...
**Fun fact:** Milton Humason, began working as a janitor at the Mt....
If you want to learn more about the Hubble constant, its implicatio...
ASTRONOMY:
E.
HUBBLE
appearance
the
spectrum
is
very
much
like
spectra
of
the
Milky
Way
clouds
in
Sagittarius
and
Cygnus,
and
is
also
similar
to
spectra
of
binary
stars
of
the
W
Ursae
Majoris
type,
where
the
widening
and
depth
of
the
lines
are
affected
by
the
rapid
rotation
of
the
stars
involved.
The
wide
shallow
absorption
lines
observed
in
the
spectrum
of
N.
G.
C.
7619
have
been
noticed
in
the
spectra
of
other
extra-galactic
nebulae,
and
may
be
due
to
a
dispersion
in
velocity
and
a
blending
of
the
spectral
types
of
the
many
stars
which
presumably
exist
in
the
central
parts
of
these
nebulae.
The
lack
of
depth
in
the
absorption
lines
seems
to
be
more
pronounced
among
the
smaller
and
fainter
nebulae,
and
in
N.
G.
C.
7619
the
absorption
is
very
weak.
It
is
hoped
that
velocities
of
more
of
these
interesting
objects
will
soon
be
available.
A
RELATION
BETWEEN
DISTANCE
AND
RADIAL
VELOCITY
AMONG
EXTRA-GALACTIC
NEBULAE
By
EDWIN
HUBBLB
MOUNT
WILSON
OBSURVATORY,
CARNSGIS
INSTITUTION
OF
WASHINGTON
Communicated
January
17,
1929
Determinations
of
the
motion
of
the
sun
with
respect
to
the
extra-
galactic
nebulae
have
involved
a
K
term
of
several
hundred
kilometers
which
appears
to
be
variable.
Explanations
of
this
paradox
have
been
sought
in
a
correlation
between
apparent
radial
velocities
and
distances,
but
so
far
the
results
have
not
been
convincing.
The
present
paper
is
a
re-examination
of
the
question,
based
on
only
those
nebular
distances
which
are
believed
to
be
fairly
reliable.
Distances
of
extra-galactic
nebulae
depend
ultimately
upon
the
appli-
cation
of
absolute-luminosity
criteria
to
involved
stars
whose
types
can
be
recognized.
These
include,
among
others,
Cepheid
variables,
novae,
and
blue
stars
involved
in
emission
nebulosity.
Numerical
values
depend
upon
the
zero
point
of
the
period-luminosity
relation
among
Cepheids,
the
other
criteria
merely
check
the
order
of
the
distances.
This
method
is
restricted
to
the
few
nebulae
which
are
well
resolved
by
existing
instru-
ments.
A
study
of
these
nebulae,
together
with
those
in
which
any
stars
at
all
can
be
recognized,
indicates
the
probability
of
an
approximately
uniform
upper
limit
to
the
absolute
luminosity
of
stars,
in
the
late-type
spirals
and
irregular
nebulae
at
least,
of
the
order
of
M
(photographic)
=
-6.3.1
The
apparent
luminosities
of
the
brightest
stars
in
such
nebulae
are
thus
criteria
which,
although
rough
and
to
be
applied
with
caution,
168
PRoc.
N.
A.
S.
ASTRONOMY:
E.
HUBBLE
furnish
reasonable
estimates
of
the
distances
of
all
extra-galactic
systems
in
which
even
a
few
stars
can
be
detected.
TABLE
1
NSBULAx
WHoss
DisTANcEs
HAvE
BSN
ESTIMATSD
FROM
STARS
INVOIVXD
OR
FROM
MEAN
LumNosrrIns
IN
A
CLUSTER
OBJUCT
m,
r
V
M
S.
Mag.
..
0.032
+
170
1.5
-16.0
L.Mag.
..
0.034
+
290
0.5
17.2
N.
G.
C.
6822
..
0.214
-
130
9.0
12.7
598
..
0.263
-
70
7.0
15.1
221
..
0.275
-
185
8.8
13.4
224
..
0.275
-
220
5.0
17.2
5457
17.0
0.45
+
200
9.9
13.3
4736
17.3
0.5
+
290
8.4
15.1
5194
17.3
0.5
+
270
7.4
16.1
4449
17.8
0.63
+
200
9.5
14.5
4214
18.3
0.8
+
300
11.3
13.2
3031
18.5
0.9
-
30
8.3
16.4
3627
18.5
0.9
+
650
9.1
15.7
4826
18.5
0.9
+
150
9.0
15.7
5236
18.5
0.9
+
500
10.4
14.4
1068
18.7
1.0
+
920
9.1
15.9
5055
19.0
1.1
+
450 9.6
15.6
7331
19.0
1.1
+
500
10.4
14.8
4258
19.5
1.4
+
500
8.7
17.0
4151
20.0
1.7
+
960
12.0
14.2
4382
..
2.0
+
500
10.0
16.5
4472
..
2.0
+
850
8.8
17.7
4486
..
2.0
+
800
9.7
16.8
4649
..
2.0
+1090
9.5
17.0
Mean
-15.5
m,
=
photographic
magnitude
of
brightest
stars
involved.
r
=
distance
in
units
of
106
parsecs.
The
first
two
are
Shapley's
values.
v
=
measured
velocities
in
km./sec.
N.
G.
C.
6822,
221,
224
and
5457
are
recent
determinations
by
Humason.
m,
=
Holetschek's
visual
magnitude
as
corrected
by
Hopmann.
The
first
three
objects
were
not
measured
by
Holetschek,
and
the
values
of
me
represent
estimates
by
the
author
based
upon
such
data
as
are
available.
Mt
=
total
visual
absolute
magnitude
computed
from
mg
and
r.
Finally,
the
nebulae
themselves
appear
to
be
of
a
definite
order
of
absolute
luminosity,
exhibiting