
9,096 Stars in the Sky – Is That All? - georgecmu
http://www.skyandtelescope.com/astronomy-resources/how-many-stars-night-sky-09172014/
======
subroutine
For those who swear they have seen a sky with more than 5k stars, next time
you're in those same wilderness and staring up at the sky there might be a way
to verify whether you are seeing ~4k or ~40k stars.

Here I've compiled a distilled version of the cited tables...

    
    
        Mag    Visual_Device         Stars    Example
        -26    naked eye (daylight)      1    Sun
        -13    naked eye (twilight)      1    full Moon
        -06    naked eye (dusk)          1    cres Moon
        -04    naked eye (metro)         2    Venus
        -02    naked eye (metro)         2    Jupiter
        -01    naked eye (metro)         2    Sirius
        +00    naked eye (city)          8    Vega
        +01    naked eye (suburb)       22    Saturn
        +02    naked eye (suburb)       93    Big Dipper
        +05    naked eye (rural)      2822    Jupiter moons
        +06    binocular (rural)      8768    Uranus
        +08    binocular (wild)      77627    Neptune
    
    

If you happen to be in a place/time-of-year to see Uranus (n.b. cool mobile
apps exist to help locate celestial bodies), you can probably see at least
4k-5k stars. If you can see Neptune with the naked eye, perhaps you are
actually seeing 30k-40k stars.

## Notes ##

Each magnitude is 2.5x brighter than the next:

> Mag+01 is 2.5 times brighter than Mag+02

> Mag+01 is 2.5*2.5 times brighter than Mag+03

Mag Scale:
[http://www.icq.eps.harvard.edu/MagScale.html](http://www.icq.eps.harvard.edu/MagScale.html)

Star Count:
[http://www.stargazing.net/david/constel/howmanystars.html](http://www.stargazing.net/david/constel/howmanystars.html)

~~~
TheOtherHobbes
If you can see Neptune with the naked eye, you're probably a genetically
altered mutant with eyes the size of melons.

Neptune is theoretically a naked eye object, barely, against a perfectly black
background. In reality the sky isn't perfectly black, even with no man-made
light sources. (See e.g. the Zodiacal Light.) So your chances of seeing +08
objects without binos or a telescope are basically zero.

I lived in a very rural area for a while with limited light sources. On a
clear night, the sky was absolutely glorious, and going for night time walks
under it was a favourite hobby.

But even on the darkest and clearest nights, with half an hour of dark
adaptation, +04/5 was as good as the view ever got without binos.

~~~
subroutine
Agreed. I wouldn't expect anyone would be able to spot Neptune. The comment
was basically about proving to yourself that you're not seeing more than ~5k
stars.

------
NKosmatos
Reminds me of the Big Dipper eye test. If you can spot the double star in Ursa
Major constellation you’re supposed to have 20/20 vision. The two stars are
Mizar (magnitude +2) and Alcor (magnitude +4). In urban environments this is a
good combined test ;-)

On a personal note (which I hope many will relate), I’ll never forget the very
first time I looked up at the night sky after getting my first pair of
glasses. The sheer number of extra stars I could see combined with the
clarity, made me fall in love with stargazing :-)

~~~
sml156
I read somewhere that in Roman times the test to become a soldier was to look
at the Pleiades cluster and if you could see seven stars you would pass the
eye test.

~~~
eesmith
That doesn't sound quite right.

Of what use is a vision test where it's easy to memorize the answer? In
English Pleiades is also known as the Seven Sisters, because of the ancient
Greek myth. I can easily believe that Pleiades was also associated with 7 in
general Roman culture.

It doesn't help that more than 7 stars can be visible.
([https://en.wikipedia.org/wiki/Pleiades](https://en.wikipedia.org/wiki/Pleiades)
says "Its light is dominated by young, hot blue stars, up to 14 of which can
be seen with the naked eye depending on local observing conditions.") Muhammad
was written to have been able to see 12.

If someone says there are 9 stars, is that a sign of good vision? Or simply a
guess?

Then there's the observation that other cultures see six stars. See
[https://en.wikipedia.org/wiki/Pleiades_in_folklore_and_liter...](https://en.wikipedia.org/wiki/Pleiades_in_folklore_and_literature)
.

In modern times only 6 stars are usually visible to the naked eye, and there
are proposals for why 7 was used in Ancient Greece; eg, stellar variability or
a numerological leaning towards 7.

------
barbegal
NASA used to run an experiment with students counting stars [1] in various
sites. The most that was counted was around 5000 which tallys up to the
theory.

[1]
[https://web.archive.org/web/20140610015945/http://starcount....](https://web.archive.org/web/20140610015945/http://starcount.msfc.nasa.gov:80/test4.cfm)

------
xref
Reminds me of William Hershel and a classic example of "if your scientific
theory relies on you being special/unique, it is almost certainly wrong"

Hershel made a lot of amazing discoveries and advancements with this
telescopes, so decided to count the stars in every direction of the sky. He
found that there were equal numbers no matter where he pointed his scope, so
we must be at the center of the universe!

[https://en.m.wikipedia.org/wiki/Galactocentrism](https://en.m.wikipedia.org/wiki/Galactocentrism)

~~~
jobigoud
Well, we are at the center of the observable universe.

~~~
nojvek
We are at the center of “our” observable universe. But ... since we don’t
still know the bounds of universe, technically we don’t exactly know where our
absolute position in the universe really is.

~~~
moopling
I was under the impression us doesn't make sense to consider the idea of
absolute position in space.

~~~
aeorgnoieang
I don't think that's completely true. Details of the cosmic microwave
background might indicate that we're at the center of the universe:

\- [Axis of evil (cosmology) -
Wikiwand]([https://www.wikiwand.com/en/Axis_of_evil_(cosmology)](https://www.wikiwand.com/en/Axis_of_evil_\(cosmology\)))

And besides the above, the CMB itself provides a 'natural absolute frame of
reference' as it's the remnants of the very early universe.

------
cryptoz
The tone of the article is a bit confusing - I suppose it is written by
someone who has a lot of experience looking up and a lot of time spent seeing
lots of stars. But as a life-long city dweller with some rural experience, I
would have guessed a max of 3,000 or so stars visible when there is no light
pollution. They call the number 9,000 "unimpressive" but to me, the idea that
my eyes could probably resolve about 9,000 stars at night is _incredibly_
impressive.

Regardless, most of humanity sees more like 10 or 200, which is super sad and
I would be interested in knowing if there are studies (or any possible way to
know) what kind of effect that might have on a population - not being able to
see the night sky well, or at all.

Edit: At night at one spot, there 4,500 visible, not 9,000 - but then we have
an odd tagline, again showing the odd choice of words by the author.

> Ten thousand stars bedazzle the eye on a dark night.

Not really? Just 4,500 if you live in the middle of no light pollution.

~~~
alphydan
Perhaps it's the contrast with the idea that the universe is vast.

Looking up at the sky gives us a sense of awe. But why? Is it because we "see
countless stars"? Apparently not. 9000 is a pretty small number compared with
the grains in a fistful of sand, or a cup of rice. So why does looking at the
starts give this sense of vastness?

It's possible that it's an acquired mode of thought. Perhaps to ancient
people, the 88 constellations (and approx 700 familiar stars in
constellations) were ... just that, a few familiar dots on the celestial
vault.

I somehow imagined I could see tens of thousands ... but had never really
bothered to count.

~~~
cryptoz
Yes, that makes sense. To me, the vastness comes from knowing how many stars
are in the dark 'gaps' I can't see with my eyes. And knowing how many of the
visible stars themselves have planets. We're getting the to point of exoplanet
discovery where you can find a star with your eyes, know which one it is, and
check to see how many planets orbit it.

So when I look up at the night sky, I can almost see all the planets orbit all
the stars up there, and all the moons around all those planets - and it _is_
vast. Even just what you can see and imagine with your own eyes and head, it's
vast. No need for looking through a telescope to get the sense of vastness -
but perhaps you do need the knowledge that stuff is _up there_ \- even if you
can't see it.

okay, a showerthought:

The ancients treated the stars and planets as Gods. And some of them have the
same characteristics - they exist for seemingly eternity, or at least billions
of years. They shine light and provide what is necessary for life to start,
and for it to go on. They are always up there, 'above', 'watching' as it were
(they send rays of light down to the planets, where it is partially absorbed
and partially bounced back). And one day, when the Sun goes out, it will end
the universe that exists on Earth. Based on what we know now, the ancients
seemed to get a lot right in the actual nature of the stars.

~~~
dotancohen
> We're getting the to point of exoplanet discovery where you can find a star
> with your eyes, know which one it is, and check to see how many planets
> orbit it.

Fomalhaut is a great example. Occasionally I'll take people out for sky tours,
and when Fomalhaut is visible I mention to them that not only is that star
extraordinarily close (25 ly), but that it has planets that we've actually
imaged in photographs!

------
sriku
[https://urbigenous.net/library/nine_billion_names_of_god.htm...](https://urbigenous.net/library/nine_billion_names_of_god.html)

Not saying anything else so I don't spoil it.

------
e12e
> At the poles, where the north and south polestars are pinned to the zenith
> and no stars rise or set, the same ~4,500 stars are visible every single
> clear night of the year.

Ofcourse, at the poles you have long polar day (midnight sun) in summer - and
will generally see only one star during the night: the sun.

Conversely, during polar night, you'll be able to see some stars for most of
the day, if not maybe a few bright stars even at noon.

~~~
Taniwha
There's a south pole star? must be new

~~~
sago
Both polestars are 'new', in the sense that precession brings different stars
closer to the pole axis over time.

Sigma Octantis (mag 5.47, ra 21h09m dec −88°57′) is the best South Pole star
within (optimistic) naked-eye range. As you can see, it is just over 1° off
axis (c.f. Polaris, which is marginally better at c. 3/4° out).

~~~
Taniwha
yes, but here in the southern hemisphere, there is no recognised "pole star"
\- mag 5.47 isn't at all bright enough to be counted

Instead we navigate by using the southern cross to find the south celestial
pole

~~~
davidcuddeback
> _here in the southern hemisphere, there is no recognised "pole star"_

My polar alignment scope has etchings for Sigma Octantis (screenshot from
companion iOS app: [1]). Wikipedia also describes Sigma Octantis as a southern
pole star [2]. Maybe it's just not as common to refer to Sigma Octantis as a
pole star as it is for Polaris, but it does seem to be recognized.

[1] [https://itunes.apple.com/us/app/astro-physics-
polaralign/id5...](https://itunes.apple.com/us/app/astro-physics-
polaralign/id555953481?ls=1&mt=8)

[2]
[https://en.wikipedia.org/wiki/Sigma_Octantis](https://en.wikipedia.org/wiki/Sigma_Octantis)

~~~
Taniwha
we're talking about naked eye stars here, again no one in the Southern
Hemisphere I've every heard of looks up and points at a "pole star"

~~~
davidcuddeback
> _we 're talking about naked eye stars here_

We're talking about pole stars. Being a naked eye star isn't a necessary
condition. Choice of a pole star is a balance between brightness and proximity
to the pole.

> _again no one in the Southern Hemisphere I 've every heard of looks up and
> points at a "pole star"_

It's never too late to learn something new. :)

More to the point, "the north and south polestars" would be well understood by
much of _Sky & Telescope's_ target audience, and that's who they're writing
for. I get that it's going to be less common knowledge outside of their target
audience, but that doesn't make the article incorrect, which seems to be what
you want to argue.

------
jhallenworld
This should be easy to verify with sampling: I mean count the stars in a spot
in the sky and extrapolate to the rest.

Actually the recent Sky and Telescope article about killer asteroids mentioned
another interesting form of sampling. The article said that astronomers have a
high confidence that 90% of all large asteroids which cross earth's orbit are
known. But how can this be? This is the argument: we "tag" an asteroid when we
find it. Then we look for these types of asteroids over some period of time.
90% of the asteroids found in this period are already tagged ones, so we know
only 10% remain.

I'm trying to get my head around the reliability of this method- at the very
least the sampling has to be non-biased and sensitive.

------
Keyframe
Would this be true from space also? Where there's no atmosphere and light
pollution.

~~~
nojvek
Kepler, Hubble and a number of other telescopes are placed in space exactly
for this reason. They can see the skies much clearly and that they can stay
focused on a tiny patch of sky for months and take a vivid picture with the
faintest of light from the distant stars.

~~~
rimliu
This is a good place to mention
[https://en.wikipedia.org/wiki/Hipparcos](https://en.wikipedia.org/wiki/Hipparcos)
and
[https://en.wikipedia.org/wiki/Gaia_(spacecraft)](https://en.wikipedia.org/wiki/Gaia_\(spacecraft\))

Had I not drop out from my PhD studies my thesis would be about photometric
system for GAIA :(

------
xefer
People should check out the free, open source sky atlas/planetarium software
Stellarium:

[http://stellarium.org](http://stellarium.org)

A sort of Google maps for the heavens. You can download star catalogs with
over 150 million stars.

It's amazing what you can do with it. Here's a little movie I made of the
2-day long transit of Uranus across the Sun as viewed from Neptune in the yer
46915:
[https://www.youtube.com/watch?v=KU9yzUUMhqU](https://www.youtube.com/watch?v=KU9yzUUMhqU)

------
tome
The moon makes up 1e-5 of the visible sky hemisphere. That means there is one
star per 11 moon-areas. That seems very low to me. I'd have guessed the ratio
was closer to 1:1. I'll check next time I'm out at night!

[https://en.wikipedia.org/wiki/Solid_angle#Sun_and_Moon](https://en.wikipedia.org/wiki/Solid_angle#Sun_and_Moon)

~~~
skykooler
Keep in mind that area is square, so that's a little over a 3x3 grid of moons.
(Well, actually a little smaller, because circles don't pack perfectly.)

------
bernardino
Reminds me how I like to ramble on to friends about how light pollution is a
serious matter, and also of Paul Bogard's The End of Night
([https://www.goodreads.com/book/show/16131044-the-end-of-
nigh...](https://www.goodreads.com/book/show/16131044-the-end-of-night)).

~~~
johan_larson
Serious? Does anyone other than astronomers care about light pollution?

~~~
logfromblammo
Some species of animals use celestial features to navigate or coordinate
mating behavior. I think the most notable are sea turtles, whose hatchlings
may be confused by artificial lights.

Somnologists also care about light pollution, particularly the colors. One
hypothesis is that artificial lighting interferes with health sleep patterns
and behaviors.

Bombardiers on nighttime missions do like to have lighted targets to aim at.

...it's not an issue that motivates many people, no.

------
sjclemmy
When they say ‘visible with the naked eye’, do they mean looking straight on
or with peripheral vision? Because you can sense more light in your periphery,
so that might explain why it seems ‘more’ than about 4500 stars you can see.

~~~
barbegal
No you genuinely can't see more than ~4500 stars. I think we imagine that we
can see more stars because we see a lot of photos taken using long exposures
that can pick out more stars [1]. A 30 second exposure can bring out several
times more stars than the human eye can see.

[1] [https://petapixel.com/2015/04/04/what-the-naked-eye-sees-
in-...](https://petapixel.com/2015/04/04/what-the-naked-eye-sees-in-the-night-
sky-compared-to-what-the-camera-can-capture/)

~~~
cynicalkane
I’ve been in parts of the country where there’s complete blackness in the new
moon. I didn’t stop to count the stars, but it looked much more like the
second picture than the first one. The Milky Way is astonishingly vivid and
the stars are endless.

The author of that article might claim the first picture is “real” in a
physical sense, but even if it was, it ceases to be when transfered to a
limited computer screen and viewed in indoor ambient light.

~~~
Retric
The second photo more closely matches what I see, though it looks more black
and white than that. I suspect there is a wide range of night vision as I have
watched people stumble around when I thought there was plenty of light.

~~~
edejong
Are you by any chance color blind?

~~~
Retric
No, but at night color becomes difficult to distinguish. It's not exactly
black and white but really muted colors.

~~~
edejong
That’s for everyone. Cones have lower sensitivity and more noise. Colorblind
people have supposedly higher quantities of rods.

------
jcims
If you calculate the diameter of most stars in the night sky, the apparent
diameter is on the order of a large molecule held at arm's length. The fact
that you can see them at all boggles my mind.

~~~
eternauta3k
Below a certain size, you're looking at the point spread function of your
eye/camera.

~~~
jcims
It never really occurred to me but I wonder how much of twinkling is due to
the light wobbling around a small set of individual rods/cones/etc.

(Also might explain why some photos show a bunch of stars that are deep
blue/red)

~~~
eternauta3k
I believe it's an atmospheric effect:
[https://en.wikipedia.org/wiki/Twinkling](https://en.wikipedia.org/wiki/Twinkling)

------
swamp40
How is it counted if you see one dot that's really a far away galaxy with a
billion stars all shining to make that one dot?

------
EGreg
This to me is one of the biggest proofs that the Torah (first part of the
Bible) wasn’t just a bunch of legends written by man.

It says that Abraham’s children will be as numerous as the sand on the
seashore and the... _stars in the sky_.

After all, as far as ancient people knew, there were millions (possibly
billions) of sand grains by the sea, and ... maybe 5,000 stars?

I am sure Greek astronomers would have laughed at any Jew who said that the
number of stars is in the millions and billions.

Yet these days with modern science we have found out that there _are_ as many
if not more stars than sand grains.

Now, an atheist would say “that was just an expression”. But who really uses
stars as an example of millions, just like sand grains, over and over
repeatedly, if they really thought there weren’t that many? It must have been
one lucky guess!

There are other proofs but this to me is one of the hardest to explain away.

* EDIT: lots of militant atheists on this site I see, wielding that downvote button rather than engaging in substantive argument _

~~~
verbify
Are you serious?

1) Surely the Bible is just making the same mistake I make when looking at the
sky - imagining that I'm seeing millions instead of just 9k.

2) If it wasn't just an expression then there are an estimated 300 billion
stars in the milky way alone. Astronomers put current estimates of the total
stellar population at roughly 70 billion trillion (7 x 1022). I don't see that
many descendants of Abraham.

Extraordinary claims require extraordinary evidence. A figure of speech that
uses the stars as a reference to a huge number is not extraordinary evidence.

~~~
EGreg
Quadrillions

[https://www.npr.org/sections/krulwich/2012/09/17/161096233/w...](https://www.npr.org/sections/krulwich/2012/09/17/161096233/which-
is-greater-the-number-of-sand-grains-on-earth-or-stars-in-the-sky)

