# Things you can, surprisingly, see with the naked eye **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 18, 2023, 7:35pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235 "2023-05-18T19:35:54Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Baal\_Houtham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baal_houtham/32/13604_2.png) [@Baal\_Houtham](https://boards.straightdope.com/u/Baal_Houtham)\ **Post date:** [May 20, 2023, 1:59am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/41 "2023-05-20T01:59:49Z")
And Venus is visible during the day — altho I’ve never gone to the work to view it then. This is one person’s method (after consulting the relevant sky charts): 1. Put a building between you and the sun. Make sure you are completely in the shade of the building and cannot see the sun. 2. Start with low-power binoculars or a hand-held 6×30 finder scope (NEVER point either of these at or near the sun!) 3. After finding Venus with the binoculars or a finder scope, slowly and carefully remove the binocular or finder scope away from your eyes, without moving your head, and try to spot Venus with your eyes. ---
**Author:** ![Uncle\_Jocko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uncle_jocko/32/2932_2.png) [@Uncle\_Jocko](https://boards.straightdope.com/u/Uncle_Jocko)\ **Post date:** [May 20, 2023, 2:14am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/42 "2023-05-20T02:14:53Z")
> [@Princhester](#): > > I miss the Iridium satellites. Iridium flashes were fun. I remember watching a group of Starlink satellites overhead a few years ago. That was cool - a line of bright dots moving across the sky like a cosmic train. ---
**Author:** ![california\_jobcase](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)\ **Post date:** [May 20, 2023, 2:15am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/43 "2023-05-20T02:15:09Z")
There was an alignment back in '97. Uranus was visible in that one. I also saw Venus in the afternoon- during the last total solar eclipse. ---
**Author:** ![wguy123](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wguy123/32/3161_2.png) [@wguy123](https://boards.straightdope.com/u/wguy123)\ **Post date:** [May 20, 2023, 2:34am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/44 "2023-05-20T02:34:46Z")
WTF? I used the search and it didn’t find the term in this thread. But, now I do it again and it finds it. Either way, my contribution still stands due to my visuals added. ---
**Author:** ![Mikkel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikkel/32/13151_2.png) [@Mikkel](https://boards.straightdope.com/u/Mikkel)\ **Post date:** [May 20, 2023, 12:25pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/45 "2023-05-20T12:25:09Z")
> [@K364](#): > > Triangulum Galaxy is 2.73 light years away I think you are missing a “million” between 2.73 and light years. Otherwise really interesting. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [May 20, 2023, 1:18pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/46 "2023-05-20T13:18:20Z")
Yes! This is my new life goal — to see Triangulum with my naked eye (I hope eyeglasses count). So, the Triangulorians are currently viewing Earth with hominids that haven’t even quite gotten to waking upright. Amazing. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 20, 2023, 1:36pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/47 "2023-05-20T13:36:50Z")
> [@wolfpup](#): > > Let me offer a diplomatic solution and suggest that you’re both right. Yes, the resolution of any given imaging technique is a matter of degree, but only within certain limits. Beyond those limits the resolution is precisely zero. It isn’t “poor” resolution, it’s zero resolution. Would you say that you can see a star with the naked eye? A nice, bright one, like Sirius, say. You can’t resolve any detail whatsoever there, either. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [May 20, 2023, 1:42pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/48 "2023-05-20T13:42:14Z")
Moderating: This isn’t a political thread, let’s keep the political digs of it. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [May 20, 2023, 2:59pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/49 "2023-05-20T14:59:20Z")
> [@Chronos](#): > > > [@wolfpup](#): > > > > Let me offer a diplomatic solution and suggest that you’re both right. Yes, the resolution of any given imaging technique is a matter of degree, but only within certain limits. Beyond those limits the resolution is precisely zero. It isn’t “poor” resolution, it’s zero resolution. > > Would you say that you can see a star with the naked eye? A nice, bright one, like Sirius, say. You can’t resolve any detail whatsoever there, either. Obviously when you look at the sky you’re really seeing Sirius. I’m not sure if you’re arguing with anything I said. I’ll explain what I meant in a bit more detail for the sake of clarity, though I’m sure none of this will be new to you. The most important difference between the Sirius example and the strontium atom experiment is firstly that the light from Sirius actually carries a wealth of information; it’s not simply a binary token for whether the star is there or not. The colour of the light tells us about its temperature, and the brightness (knowing the distance) about its absolute intensity and size. But far beyond that, with a sufficiently powerful telescope one could theoretically observe detail on such a star or a planet – stressing here the importance of the qualifiers “sufficiently powerful” and “theoretically”. In practice, Rayleigh diffraction (the Rayleigh criterion) limits the resolving ability of even the best real-world telescopes out beyond the troublesome atmosphere, but only because there are real-world limitations on the size of the aperture (e.g.- mirror). The smallest angle between two points that can be resolved by a theoretically perfect telescope is θ = 1.22 λ/D, thus the resolution is proportional to the size of the aperture _D_ and inversely proportional to the wavelength of the light being observed. Whereas in the strontium atom experiment, the observed dot can be regarded as simply a proxy for the atom – it tells us whether it’s there or not, but nothing more about it. You can magnify the hell out of it, there’s nothing more there. And, although the Rayleigh criterion has some relevance to microscopy within the limits of optical performance, there you run into absolute hard limits with optical microscopes due to the wavelength of visible light. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [May 20, 2023, 4:08pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/50 "2023-05-20T16:08:48Z")
> [@wolfpup](#): > > The most important difference between the Sirius example and the strontium atom experiment is firstly that the light from Sirius actually carries a wealth of information; it’s not simply a binary token for whether the star is there or not. The colour of the light tells us about its temperature, and the brightness (knowing the distance) about its absolute intensity and size. But far beyond that, with a sufficiently powerful telescope one could theoretically observe detail on such a star or a planet – stressing here the importance of the qualifiers “sufficiently powerful” and “theoretically”. That stuff is mostly not naked-eye information, though. The Sr atom image may in fact provide more information about the atom if you were to analyze it with analytical thingies, but what we can learn from just by looking at the atom or Sirius are not appreciably different. ---
**Author:** ![FloatyGimpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/floatygimpy/32/7750_2.png) [@FloatyGimpy](https://boards.straightdope.com/u/FloatyGimpy)\ **Post date:** [May 20, 2023, 4:22pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/51 "2023-05-20T16:22:43Z")
> [@JKellyMap](#): > > And anyone there who’s looking at us…is seeing a planet that includes a primate, Australopithecus, that has just started walking upright, but isn’t especially numerous or notable. Well there’s something I’ve never thought about before! I love looking at celestial objects and thinking about the fact that I’m looking at something as it was a long time ago but I’ve never thought about somebody looking back at us and what they would be seeing. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [May 21, 2023, 6:45am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/52 "2023-05-21T06:45:53Z")
In the early 60s, the Echo I satellite would occasionally be visible. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 21, 2023, 11:15am UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/53 "2023-05-21T11:15:23Z")
For the purposes of this thread, I guess the OP gets to decide what counts as “seeing with the naked eye.” But to my mind, if something at “normal” illumination levels (outdoors on a sunny day, indoors under conventional residential/commercial lighting) reflects or emits enough light toward my eye to register on at least one rod or cone with enough intensity to differentiate it from the background, then I am seeing it. So, distant license plate that’s unreadable, but visible as a lighter patch on a dark-painted vehicle? Sure. Space station that looks like a pinpoint of light on a dark background? I’m seeing it, just as surely as I’m seeing planets and stars. The laser-illuminated strontium atom, while quite interesting, shouldn’t count. As mentioned in the article: > [@](#): > > [David Nadlinger](http://klickverbot.at/)‘s photo, Single Atom In An Ion Trap, was captured through the window of a vacuum chamber in an Oxford University laboratory, using an ordinary digital camera on a long exposure shot. If you have to use a long exposure to just barely capture an image of an object, then said object is almost certainly too dim to see with the naked eye, despite what the article says. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [May 21, 2023, 4:58pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/54 "2023-05-21T16:58:56Z")
> [@Machine\_Elf](#): > > If you have to use a long exposure to just barely capture an image of an object, then said object is almost certainly too dim to see with the naked eye I have to disagree. On a dark night, I can see very faint objects in the sky (probably stars, maybe asteroids or satellites) that a camera would not be able to record without a several-second exposure. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 21, 2023, 9:40pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/55 "2023-05-21T21:40:54Z")
> [@eschereal](#): > > I have to disagree. On a dark night, I can see very faint objects in the sky (probably stars, maybe asteroids or satellites) that a camera would not be able to record without a several-second exposure. That’s a pretty bad camera, then. CCDs have a much higher sensitivity than the human retina. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [May 21, 2023, 9:56pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/56 "2023-05-21T21:56:28Z")
> [@Dr.Strangelove](#): > > The laser is just illumination, though. There are lots of things you can only see when illuminated in a particular way. As long as it’s photons coming off the object and going directly into your eye, I’d say it counts. I agree. The issue isn’t the laser. But from the article, he set up an ordinary camera and took a long exposure. It doesn’t say that he could see it without the camera. He talks about seeing it “with the naked eye”, but it’s not clear that he’s using an appropriate definition of what that means. Requiring a camera with a long exposure isn’t what most people would mean by “with the naked eye”. However… I’m guessing that this would be a good excuse to get funding for a more powerful laser. ETA: having said that, it seems that the rest of the photo is not massively overexposed. So I think it could not have a been a super long exposure, meaning that it must be very nearly visible. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 21, 2023, 10:09pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/57 "2023-05-21T22:09:57Z")
> [@Riemann](#): > > Requiring a camera with a long exposure isn’t what most people would mean by “with the naked eye”. I did a bit of Googling and found the author’s blog: [https://klickverbot.at/blog/2018/02/photographing-a-single-atom/](https://klickverbot.at/blog/2018/02/photographing-a-single-atom/) Unfortunately, it also declines to say whether it was naked-eye visible. However, it mentions previous experiments where the atom was visible with small amounts of magnification. One of those is here: > **[The Impossible Observed](https://link.springer.com/chapter/10.1007/978-1-4612-4030-3_15)** > > In 1979 in Heidelberg, Germany, Dr. Werner Neuhauser looked up from the eyepiece of a low-power microscope and fancied he heard the ghost of Mach whispering: “Now I believe in atoms.” Neuhauser had just glimpsed what appeared to be a bright blue... > **I** n 1979 in Heidelberg, Germany, Dr. Werner Neuhauser looked up from the eyepiece of a low-power microscope and fancied he heard the ghost of Mach whispering: “Now I believe in atoms.” **Neuhauser had just glimpsed what appeared to be a bright blue star floating in the void; it was a single barium ion, caught in an electromagnetic trap and fluorescing in a laser’s beam**. Thus transpired the first observation of an isolated atom using a lens; **soon one would be glimpsed with the naked eye as well**. (When I was a child, elementary science textbooks claimed that no one would ever see an atom with the naked eye. The authors had erred by assuming that _smallness_ was the important issue; actually, _brightness_ and _isolation_ from other atoms are what matters. **The laser-stimulated barium atom produces 10^8 photons per second; your eyes can collect several thousand. The normal retina is sensitive to even a few photons, so you can see the atom, just as you would a distant star or any other bright, isolated object.** ) So, it sounds plausible. It probably requires some dark adaptation and the removal of any other light sources in the room, which the linked experiment may or may not have done. But it was apparently done back in 1979, at least. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 21, 2023, 10:15pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/58 "2023-05-21T22:15:29Z")
> [@Chronos](#): > > CCDs have a much higher sensitivity than the human retina. Only in some ways. The retina is sensitive to a handful of photons per second. It’s pretty good at integrating over time, so it may well take a multi-second exposure to produce something equivalent to what a dark-adapted eye can detect. Those are the rods of course; the cones are much less sensitive but necessary for color vision. The CCD wins there. But for pure, unmagnified sensitivity, the eye does pretty well. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [May 21, 2023, 11:37pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/59 "2023-05-21T23:37:31Z")
> [@rowrrbazzle](#): > > In the early 60s, the Echo I satellite would occasionally be visible. I remember as a kid seeing several satellites. Back when I lived/visited areas with crystal clear skies at night. My Echo memory is messed up. I thought I saw Echo I at a place we lived at… before 1960. But that’s not possible. So I think it was another very late 50s satellite. The coolest one was one in polar orbit going north to south c. 1976,. It was early night and I was in a sleeping bag looking for falling stars, as one does in such situations, when I noticed a “star” moving. It was moving too slowly to be a plane, etc. (Sadly the places I visited then that had such clear skies are now all too hazy in the summer due to fires. I haven’t seen the Milky Way since 1997.) ---
**Author:** ![Yelnick\_McWawa](https://avatars.discourse-cdn.com/v4/letter/y/839c29/32.png) [@Yelnick\_McWawa](https://boards.straightdope.com/u/Yelnick_McWawa)\ **Post date:** [May 23, 2023, 12:42pm UTC](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235/60 "2023-05-23T12:42:02Z")
> [@Elmer\_J.Fudd](#): > > It was probably the much larger rocket booster; not Sputnik. (See Post 9). I saw your post after I had made mine. For 65+ years, I thought I’d seen Sputnik. Still, it was quite an impressive feat. While going to the moon was a major leap of progress, I consider Sputnik to be a slightly larger leap. [Previous page](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235.md?page=2) [Next page](https://boards.straightdope.com/t/things-you-can-surprisingly-see-with-the-naked-eye/984235.md?page=4)