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9,096 Stars in the Sky – Is That All?

264 points by georgecmu 9y ago

sjclemmy 9y ago
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.
- tobiasSoftware 9y ago
  Neither, they mean total stars you can count if you look all around the night sky. The article says that it's about 9000 stars total, but then the ground blocks our view of the half of the stars that are on the hemisphere on the opposite side of the world.
- barbegal 9y ago
  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-the-night-sky-compared-to-what-the-camera-can-capture/ https://petapixel.com/2015/04/04/what-the-naked-eye-sees-in-...
  - cynicalkane 9y ago
    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 9y ago
      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 9y ago
        Are you by any chance color blind?
        Retric 9y ago
        No, but at night color becomes difficult to distinguish. It's not exactly black and white but really muted colors.
        edejong 9y ago
        That’s for everyone. Cones have lower sensitivity and more noise. Colorblind people have supposedly higher quantities of rods.
    - JohnDotAwesome 9y ago
      > 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. I just got back from Exuma Island in the Bahamas. This is a decently remote island without much light pollution. It was by far the best star-gazing I've ever experienced. I've backpacked in Big Bend, Yosemite, and Yellowstone (and less notable areas), Exuma takes the cake for looking at the heavens. I say all of this because the picture on the left seems much more representative of the _best star-gazing conditions I've ever witnessed_. The Milky Way was big and beautiful; It caused my S.O. and I to sit outside for 1.5 hours just staring. But it still looked more like the first picture. Maybe you were mis-remembering, or maybe your vision is just better for these sorts of things. Either way, I want to know where you were to see the second picture.
    - 9y ago
- Starwatcher2001 9y ago
  Peripheral vision (or averted vision as it's usually called) is useful to master in astronomy, often used when looking at feint defuse objects like galaxies through a telescope. As you say, the rods at in peripheral part of the eye are better suited to low light. I'm not sure how well this might work with pointed sources of light like stars though.
cryptoz 9y ago
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 9y ago
  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 9y ago
    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.
EGreg 9y ago
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
- skummetmaelk 9y ago
  A broken clock is right twice a day.
- verbify 9y ago
  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 9y ago
    Quadrillions 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 https://www.npr.org/sections/krulwich/2012/09/17/161096233/w...
- throwa_way_ 9y ago
barbegal 9y ago
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.msfc.nasa.gov:80/test4.cfm https://web.archive.org/web/20140610015945/http://starcount....
e12e 9y ago
> 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 9y ago
  There's a south pole star? must be new
  - sago 9y ago
    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 9y ago
      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
      - lopmotr 9y ago
        Just because people don't use it for navigation doesn't mean it doesn't exist. It would be much more complicated to explain the orientation of the southern cross in the article. Pole star is more suitable for use there, so they used it.
      - davidcuddeback 9y ago
        > 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/id555953481?ls=1&mt=8 https://itunes.apple.com/us/app/astro-physics-polaralign/id5... [2] https://en.wikipedia.org/wiki/Sigma_Octantis https://en.wikipedia.org/wiki/Sigma_Octantis
deleted 9y ago
[deleted]
subroutine 9y ago
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
- vvanders 9y ago
  The one that really floored me was getting moving out to an area that's dark enough to see the milky way without help after ~11pm. Very few experiences as humbling as stepping outside and seeing it streak across the sky.
  - daurnimator 9y ago
    Where do you live that you can't see the milky way? I can see it from my inner-city apartment on a clear night.
    - mikekchar 9y ago
      It might sound like a crazy question, but are you sure you were seeing the milky way? If you have any streetlights at all on your street, there is no way that you can see it with the naked eye (magnitude +5-+6). If you live in the north, it's more likely that you were seeing the aurora.
NKosmatos 9y ago
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 9y ago
  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 9y ago
    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_literature https://en.wikipedia.org/wiki/Pleiades_in_folklore_and_liter... . 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.
xref 9y ago
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 9y ago
  Well, we are at the center of the observable universe.
  - nojvek 9y ago
    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 9y ago
      I was under the impression us doesn't make sense to consider the idea of absolute position in space.
      - aeorgnoieang 9y ago
        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.
- rimliu 9y ago
  Center of the galaxy. And he must be counting stars in the galactic plane not in every direction.
bernardino 9y ago
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-night https://www.goodreads.com/book/show/16131044-the-end-of-nigh...).
- johan_larson 9y ago
  Serious? Does anyone other than astronomers care about light pollution?
  - logfromblammo 9y ago
    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.
Keyframe 9y ago
Would this be true from space also? Where there's no atmosphere and light pollution.
- nojvek 9y ago
  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 9y ago
    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 :(
sriku 9y ago
https://urbigenous.net/library/nine_billion_names_of_god.html https://urbigenous.net/library/nine_billion_names_of_god.htm... Not saying anything else so I don't spoil it.
jcims 9y ago
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 9y ago
  Below a certain size, you're looking at the point spread function of your eye/camera.
  - jcims 9y ago
    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 9y ago
      I believe it's an atmospheric effect: https://en.wikipedia.org/wiki/Twinkling https://en.wikipedia.org/wiki/Twinkling
- deleted 9y ago
  [deleted]
xefer 9y ago
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 9y ago
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 9y ago
  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.)
swamp40 9y ago
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?
jhallenworld 9y ago
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.

264 points by georgecmu 9y ago

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.

tobiasSoftware 9y ago
Neither, they mean total stars you can count if you look all around the night sky. The article says that it's about 9000 stars total, but then the ground blocks our view of the half of the stars that are on the hemisphere on the opposite side of the world.
barbegal 9y ago
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-the-night-sky-compared-to-what-the-camera-can-capture/ https://petapixel.com/2015/04/04/what-the-naked-eye-sees-in-...
- cynicalkane 9y ago
  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 9y ago
    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 9y ago
      Are you by any chance color blind?
      - Retric 9y ago
        No, but at night color becomes difficult to distinguish. It's not exactly black and white but really muted colors.
        edejong 9y ago
        That’s for everyone. Cones have lower sensitivity and more noise. Colorblind people have supposedly higher quantities of rods.
  - JohnDotAwesome 9y ago
    > 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. I just got back from Exuma Island in the Bahamas. This is a decently remote island without much light pollution. It was by far the best star-gazing I've ever experienced. I've backpacked in Big Bend, Yosemite, and Yellowstone (and less notable areas), Exuma takes the cake for looking at the heavens. I say all of this because the picture on the left seems much more representative of the _best star-gazing conditions I've ever witnessed_. The Milky Way was big and beautiful; It caused my S.O. and I to sit outside for 1.5 hours just staring. But it still looked more like the first picture. Maybe you were mis-remembering, or maybe your vision is just better for these sorts of things. Either way, I want to know where you were to see the second picture.
  - 9y ago
Starwatcher2001 9y ago
Peripheral vision (or averted vision as it's usually called) is useful to master in astronomy, often used when looking at feint defuse objects like galaxies through a telescope. As you say, the rods at in peripheral part of the eye are better suited to low light. I'm not sure how well this might work with pointed sources of light like stars though.

cryptoz 9y ago

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 9y ago
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 9y ago
  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.

EGreg 9y ago

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

skummetmaelk 9y ago
A broken clock is right twice a day.
verbify 9y ago
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 9y ago
  Quadrillions 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 https://www.npr.org/sections/krulwich/2012/09/17/161096233/w...
throwa_way_ 9y ago

barbegal 9y ago

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.msfc.nasa.gov:80/test4.cfm https://web.archive.org/web/20140610015945/http://starcount....

e12e 9y ago

> 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 9y ago
There's a south pole star? must be new
- sago 9y ago
  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 9y ago
    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
    - lopmotr 9y ago
      Just because people don't use it for navigation doesn't mean it doesn't exist. It would be much more complicated to explain the orientation of the southern cross in the article. Pole star is more suitable for use there, so they used it.
    - davidcuddeback 9y ago
      > 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/id555953481?ls=1&mt=8 https://itunes.apple.com/us/app/astro-physics-polaralign/id5... [2] https://en.wikipedia.org/wiki/Sigma_Octantis https://en.wikipedia.org/wiki/Sigma_Octantis

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subroutine 9y ago

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

vvanders 9y ago
The one that really floored me was getting moving out to an area that's dark enough to see the milky way without help after ~11pm. Very few experiences as humbling as stepping outside and seeing it streak across the sky.
- daurnimator 9y ago
  Where do you live that you can't see the milky way? I can see it from my inner-city apartment on a clear night.
  - mikekchar 9y ago
    It might sound like a crazy question, but are you sure you were seeing the milky way? If you have any streetlights at all on your street, there is no way that you can see it with the naked eye (magnitude +5-+6). If you live in the north, it's more likely that you were seeing the aurora.

NKosmatos 9y ago

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 9y ago
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 9y ago
  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_literature https://en.wikipedia.org/wiki/Pleiades_in_folklore_and_liter... . 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.

xref 9y ago

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 9y ago
Well, we are at the center of the observable universe.
- nojvek 9y ago
  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 9y ago
    I was under the impression us doesn't make sense to consider the idea of absolute position in space.
    - aeorgnoieang 9y ago
      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.
rimliu 9y ago
Center of the galaxy. And he must be counting stars in the galactic plane not in every direction.

bernardino 9y ago

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-night https://www.goodreads.com/book/show/16131044-the-end-of-nigh...).

johan_larson 9y ago
Serious? Does anyone other than astronomers care about light pollution?
- logfromblammo 9y ago
  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.

Keyframe 9y ago

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

nojvek 9y ago
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 9y ago
  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 :(

sriku 9y ago

https://urbigenous.net/library/nine_billion_names_of_god.html https://urbigenous.net/library/nine_billion_names_of_god.htm... Not saying anything else so I don't spoil it.

jcims 9y ago

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 9y ago
Below a certain size, you're looking at the point spread function of your eye/camera.
- jcims 9y ago
  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 9y ago
    I believe it's an atmospheric effect: https://en.wikipedia.org/wiki/Twinkling https://en.wikipedia.org/wiki/Twinkling
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xefer 9y ago

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 9y ago

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 9y ago
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.)

swamp40 9y ago

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?

jhallenworld 9y ago

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.