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The frequently circulated image of Andromeda as seen if it were brighter depict it at over 8.5 times the average angular diameter of the Moon. It is supposed to be only roughly 5.6 times the diameter. I hope we stop circulating this misinformation. (imgur.com)

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[–]Baseballogy [スコア非表示]  (39子コメント)

Why is it that we are unable to see Andromeda anyway? Is it because the light rays are too scattered since their source is so far away?

[–]Strangely_quarky [スコア非表示]  (20子コメント)

You can see Andromeda though. Under very clear skies, it is visible as a fuzzy patch.

[–]pman82 [スコア非表示]  (18子コメント)

Yeah, I go to dark sites around the west with my Dob. You can see Andromeda in your peripheral vision pretty easily. It is huge. I love clear and dark night skies! Especially sleeping under them in my hammock.

[–]--lolwutroflwaffle-- [スコア非表示]  (12子コメント)

You can see Andromeda in your peripheral vision pretty easily.

I'm not sure I understand what this means, exactly. You can't look at it directly?

[–]disgustipated [スコア非表示]  (0子コメント)

It's called averted vision. The focal point of your eyeball is more attuned to capturing detail, not light. So when you look just to the side of a dim object, it will appear brighter in your peripheral vision.

[–]hstacey [スコア非表示]  (0子コメント)

Rod cells, which do not detect colour but are more sensitive in low light, are concentrated at the periphery of the retina. That is why things appear black and white in the dark, rather than in colour, and why you can often see faint things only when you're not looking directly at them.

[–]iwannaputitinurbutt [スコア非表示]  (1子コメント)

It's one of those things where if you look right at it you can't see it. It's too small and blurry to focus on.

[–]TheOldGods [スコア非表示]  (0子コメント)

It's not that it's too small and blurry to focus on.

It has to do with how light enters your eye.

Edit: actually it has to do with the light sensitivity of the cones in the center of your eye.

https://www.reddit.com/r/explainlikeimfive/comments/3maw14/eli5_why_cant_we_see_something_in_the_dark_when/

[–]harrienstyling [スコア非表示]  (0子コメント)

You have more rods in your eye which are located less central in your eye than cones. When you look indirectly at Andromeda using your peripheral vision, your rods get more light which allow you to resolve a bit better than looking directly at it.

[–]pwasma_dwagon [スコア非表示]  (0子コメント)

Your peripheral vision is... uh... "better" at seeing things. Studied it in spanish so no idea how to explain it, but the light receptors in your eyes are more sensitive to light around your retina instead of the center. For night time you use the rods, wich are more sensitive to light, while during day time you use the cones, wich require more light to be "activated" and provide you fine details and color.

Try this if you ever have a clear night sky: pick a star from your peripheral vision and then try to focus your vision on it. Sometimes, the dimmer stars will dissapear from sight once you focus on them, but if you look to the side they reapear in your peripheral vision. If i'm not making this up (its been so long ago i dont remember haha), its because the Rods are on the edges of your retina, while the cones are in the center.

[–]wildcard5 [スコア非表示]  (0子コメント)

Have you ever been inside a dark room with a window and curtains drawn over it. If you look directly at it and the light that's coming through is extremely less (this part is important) than you will notice it seems brighter when you aren't focusing at it but a little adjacent to it.

The reason this happens is because there are two types of receptors in your eyes. Rods and cones. Cones help you see in light and can detect colours. Rods help you see in the dark but can only provide black and white vision. Inside the eye, the cones are concentrated in the centre and mostly lack rods, this area is called the fovea centralis.

Since stars are best visible in the dark and even than most are very dim, we rely on rods to see them, but when you focus directly at them you are using mostly cones which are no good in bad lighting but when you look just adjacent to it than you are using cones and will notice that the stars, or Andromeda, looks much brighter.

Try this experiment
Pick a coloured marker without looking at its colour. Hold it in your hand and extend your arm at 90 degrees to one side. Now slowly bring it move tour arm so it comes in front of you and keep looking straight ahead. You will notice that even though you can see the marker in your hand, you will not be able to tell it's colour until you bring it in front of your face. That's because rods can't see colour but cones can.

English is not my first language so if you find any errors, do correct me. I'm here to learn.

コメントをもっと表示する (4 返事)

    [–]ddrt [スコア非表示]  (2子コメント)

    What does Dob stand for?

    コメントをもっと表示する (2 返事)

      [–]british_sam [スコア非表示]  (0子コメント)

      Can confirm. Seen many fuzzy patches on clear nights

      [–]GSlayerBrian[S] [スコア非表示]  (14子コメント)

      Yes, that's pretty much it. We can't even see most of the stars within our own galaxy with the naked eye due to how magnitude brightness falls off with distance. The only reason we can catch a glimpse of Andromeda at all is because its cumulative light is great enough that just barely enough can pass through the rather small aperture of our pupil that we can perceive it as, is commonly described, a fuzzy patch.

      [–]dumptrucks [スコア非表示]  (11子コメント)

      Apparently frogs can see individual photons. I wonder what Andromeda looks like to them.

      [–]pogrmman [スコア非表示]  (8子コメント)

      Our rods can also detect single photons. That's why you can see things like Andromeda galaxy better by not looking directly at it. We don't have many rods in the center of our vision. The biggest reason it isn't brighter is because our pupil is only ~6 mm in diameter in the dark.

      Also, Andromeda galaxy is pretty noticeable in dark skies. I can even see it from my house sometimes with averted vision, and the limiting magnitude here is only like 5.1 on a good night. Most of the time the limiting magnitude is like 4.5-ish. A real challenge is seeing the Triangulum galaxy with the naked eye. It is certainly doable from a very dark site (I've seen it!)

      [–]coolbho3k [スコア非表示]  (3子コメント)

      So what if you used those eye drops you get at the optometrist that make your pupils dilate? Would you see the stars better?

      [–]menkar [スコア非表示]  (0子コメント)

      After enough time in the dark your pupils will dilate like that on their own.

      [–]sylban [スコア非表示]  (0子コメント)

      In my experience, those drops make your vision blurrier. You might detect the light better, but that won't make it resolve into a coherent image for you.

      [–]pogrmman [スコア非表示]  (0子コメント)

      Not really. The issue with that is that things like spherical aberration are much more apparent because you are using the outer parts of the lens in your eye. This is why things look blurry when you have those drops in. That would negate any effect that a bigger aperture would have in seeing fainter stars.

      [–]Tokyo__Drifter [スコア非表示]  (1子コメント)

      That explains why I can see things better in my peripheral vision in the dark.

      Pitch black room, can't see a thing, but can see the wall out of the corner of my eye. Turn to look, it darkens to nothing.

      [–]Sw00ty [スコア非表示]  (0子コメント)

      Correct. Your eyes have both rod and cone cells. The rod cells are used for light sensitivity, while the cone cells are used for color sensitivity. Your peripheral vision has many more rod cells than cone cells, while the opposite is true for your central vision. This is why it is difficult to make out the color of things in your periphery, but easier to detect things in dim light.

      [–]Malbranch [スコア非表示]  (0子コメント)

      Side note, this is partially why colors, and especially stars, can be so vivid when you're on certain drugs.

      There's a part of me that wants to find a pupil dilating compound and mix it with some Chlorin e6 in some eye drops, then find a nice dark sky to see what it's like to have night vision like that. Neither of those are intoxicants btw.

      [–]Dogalicious [スコア非表示]  (0子コメント)

      Let a alone a low-flying Dragon fly that represents your next meal.

      [–]stpetestudent [スコア非表示]  (1子コメント)

      Magnitude doesn't "fall off with distance." Magnitude is just measuring the luminosity of visible light from one location. Some stars that burn especially bright can appear more luminous than stars that are much closer to us.

      And, to better answer u/Baseballogy's question, you can see Andromeda with the naked eye, but only the core of the galaxy is bright enough to be seen and that's where we see the 'fuzzy patch' and the reason why it looks so much smaller than it does in this image (even the corrected image). In fact, the outer arms of the galaxy which take up the majority of the cited image are so faint they can be difficult to see in most telescopes and only show up well in long exposure photographs.

      [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

      Right, I meant brightness rather than magnitude (realized my mistake and said brightness instead in another comment).

      [–]Sapiogram [スコア非表示]  (0子コメント)

      Pretty much. The farther away an object is, the less of its photons hit your eye.

      EDIT: Spelling

      [–]gr8ca9 [スコア非表示]  (0子コメント)

      The first time I was able to photograph it with a newer high ISO camera I was stunned at the relative size and closeness.

      [–]gaspah [スコア非表示]  (0子コメント)

      It's this very question that I think that the technical inaccuracies in this image is forgivable, as I think it does more good than bad. The slight exaguration of Andromeda's size in the night sky highlights the fact that it is a comparitively large celestial object from our point of view (the largest if you exclude the Milky Way). I'd say most people would've previously thought that it was to small to see rather than not luminous enough to be clearly visible. With the Hubble Deep Field being all that I knew about extraglactic imaging, I assumed all galaxies outside of our own were only visible via this method.

      Making something larger than life attracts more widespread attention, and I think people learning Andromeda is larger than stars and even the moon is more important than a precise comparison. To the average person it is of little consequence being slightly mislead on the subject, and anyone who is serious on the subject of astronomy will quickly be corrected on the subject.

      [–]lambo1216 [スコア非表示]  (35子コメント)

      It'll seem insignificant to a lot of people but I'd like to thank you for your post. It's this kind of self checking information that makes reddit so powerful.

      [–]randomaccount1451435 [スコア非表示]  (5子コメント)

      Self checking?

      Powerful?

      What's this site you go to, I think I might like to check it out.

      [–]PenOptimist [スコア非表示]  (2子コメント)

      Reddit gets a lot of crap, but I think it's pretty good at calling bullshjt

      コメントをもっと表示する (1 返事)

        [–]MrBullyGoat [スコア非表示]  (1子コメント)

        It's this kind of self checking information that makes reddit so powerful.

        Great point. If you can't trust reddit user G Slayer Brian, who can you trust. Honestly, did you check to make sure he/she/it didn't make it up?

        [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

        The GSlayer is something I prefix to many of my usernames because of my website, Game Slayer. But I wouldn't expect a Goat to understand.

        [–]GSlayerBrian[S] [スコア非表示]  (12子コメント)

        I just got really tired of seeing a grossly inaccurate image shared almost monthly. I had given up on trying to correct it, because it never seemed to have helped - people just kept posting the inaccurate one.

        I hope this post can help lay it to bed, but I doubt it will. I think people stumble across the article where the original image is, share it to /r/pics, then it gets shared to /r/space, and sometimes /r/woahdude. Nobody seems to check karmadecay to see if it's been posted before, so they don't see the comments of people saying that it's inaccurate.

        [–]herptydurr [スコア非表示]  (0子コメント)

        I've also seen this one circulated quite a bit which is pretty close to the proportions in your corrected image, so fear not, not all hope is lost.

        [–]opie2 [スコア非表示]  (0子コメント)

        As a photographer it drive me crazy when I see what are clearly Photoshopped versions of the moon that depict it as being outrageously huge on the horizon - if it were that close to the Earth it would probably cause a 40' tide.

        [–]didsignupforthis [スコア非表示]  (0子コメント)

        Seeing as its such a slight difference to the eye, I'd say this isn't the last you've seen of your battle.

        [–]aussiesd1 [スコア非表示]  (0子コメント)

        Thanks for correcting this information. It's not often that factual information makes it into these type of threads.

        [–]benihana [スコア非表示]  (7子コメント)

        It's this kind of self checking information that makes reddit so powerful.

        lol. did you guys know that fact checking only happens on reddit?

        people assumed this sort of thing would make open systems more powerful (many eyes make all bugs shallow), but we're finding it may not be the case (e.g. heartbleed). So yeah, how about complimenting the individual who stepped up and provided better information, not the platform.

        Thanks OP. You're the hero the internet needs.

        [–]GSlayerBrian[S] [スコア非表示]  (6子コメント)

        Thank you! I've been facing a bit of hostility from a few people who say "Why does it matter?" and seem to imply that I'm missing some sort of big picture... but to reiterate what I've said in response to them: If we all did our part to route out even seemingly trivial inaccuracies, all it could do is give us a cumulatively better understanding of our universe. And that's what science is all about.

        [–]ThreeTimesUp [スコア非表示]  (0子コメント)

        You… you're upset because somebody is wrong on the internet??

        [–]Denning_was_right [スコア非表示]  (4子コメント)

        Because it doesn't have any relevance to the image.

        If this was a blueprint people were using to size the galaxy it would be relevant, but the size of the galaxy in the picture isn't going to be used for anything, and therefore correcting it has no utility.

        Correcting it especially doesn't deepen anyone's understanding of the universe, it just devolves reddit into the same predictable one-upping for upvotes before any kind of meaningful conversation develops.

        [–]theValeofErin [スコア非表示]  (1子コメント)

        It seems pretty simple to me. An image was circulating around saying what Andromeda would like if it were brighter. OP noticed a miscalculation on the sizing of Andromeda and made a more accurate image for people to reference. Any intelligent person will take the more accurate image over the overexagerated one.

        [–]KStreetFighter2 [スコア非表示]  (1子コメント)

        So then why do you care?

        [–]encephlavator [スコア非表示]  (0子コメント)

        He doesn't. Quite likely a troll account, 8 months old with only 1 link karma.

        [–]dissident07 [スコア非表示]  (5子コメント)

        Geez... as a scientist I appreciate the technical correction of this image, but my initial intrigue and interest has now dropped below being statistically significant and is now just noise.

        "meh... it's just Andromeda, bother me when Pluto is a planet again"

        [–]captainstardriver [スコア非表示]  (1子コメント)

        I am glad this was posted because I learned something but I am also thinking this is the astronomer's equivalent of pointing out the incorrect use of "your."

        [–]alflup [スコア非表示]  (9子コメント)

        Quite frankly to my untrained eye the two Andromedas look about the same size.

        "Is it bigger than the moon?"

        "Yes"

        "OK"

        [–]dumptrucks [スコア非表示]  (0子コメント)

        Still pretty damn big in the sky if you ask me.

        [–]encephlavator [スコア非表示]  (7子コメント)

        Quite frankly to my untrained eye the two Andromedas look about the same size.

        You must have missed my animated gif comparison. The smaller is more accurate. On my monitor the smaller Andromeda = 58mm wide and the Moon = 10mm wide. The 5 to 6 full moon widths to 1 Andromeda is undisputed.

        "Is it bigger than the moon?"

        That's not the point. The point is people are posting the erroneously large Andromeda and stating as fact "here's how Andromeda would look if it were brighter." For example, yesterday: here And they're not even giving credit to the original creator, who has chimed in and supported the technical correction. So there.

        [–]pcweber111 [スコア非表示]  (1子コメント)

        Cant...watch...seizing...up...

        [–]shimapanlover [スコア非表示]  (1子コメント)

        This gif could be a before/after comparison in a couple of million (?) years.

        [–]Ramsesthesecond [スコア非表示]  (0子コメント)

        Yup. Foresight has to be more than 20/20 in this one.

        [–]Violets-Are-Blue [スコア非表示]  (0子コメント)

        Wow!! I just watched the gif. I never realized that Andromeda changes size so rapidly in the night sky. I'm gonna post this to /r/gifs and make sure everyone on reddit knows about the amazing size-changing properties of Andromeda. #WeLoveSpace

        [–]PM_ME_UR_A-B_Cups [スコア非表示]  (0子コメント)

        I've never even heard of this innaccurate comparison, so I find learning this new and supposedly less impressive figure...impressive!!

        Thanks

        [–]yatpay [スコア非表示]  (2子コメント)

        Oh no! I've been part of the problem! I'll use this one now.

        [–]wildcard5 [スコア非表示]  (1子コメント)

        Hey guys! I found him. Get your pitchforks!

        [–]JesusHMontgomery [スコア非表示]  (0子コメント)

        I am very disappointed with reality that Andromeda doesn't look like that in our sky.

        [–]encephlavator [スコア非表示]  (8子コメント)

        Animated gif comparing the two, the smaller is more accurate. link

        In case someone missed my other comment (in the other thread yesterday), here's some background on Andromeda vs The Moon:

        First, fwiw: Original post and credit should go to u/tombh, Dec 30, 2013, here

        There are 2 versions (maybe more) of this pic going around. The angular size of the moon stays the same while the angular size of Andromeda changes. Version 1 shows Andromeda at 88mm measured with a ruler held up to my monitor while version 2 measures 58mm. The moon = 10mm in both pics. If the angular size of Andromeda is 5-6 times that of the moon, then the smaller version is the correct one. Yeah, sure it's nitpicking, it's a great pic either way.

        Phil Plait of badastronomy.com covered it here on January 1, 2014.

        A similar one from Dec 28, 2006 APOD

        Edit: AFAIK, in Feb 2015, GSlayerBrian first noticed the widely circulated version is inaccurate. here

        [–]PHalfpipe [スコア非表示]  (4子コメント)

        Well, the larger one will still be accurate in a few million years.

        [–]flukshun [スコア非表示]  (1子コメント)

        Would love to see a time lapsed version of this

        [–]AtomicFreeze [スコア非表示]  (0子コメント)

        https://youtu.be/qnYCpQyRp-4?t=3m3s

        Skips quite a bit of time, but it still shows various stages. There are also some animations from different perspectives earlier in the video.

        [–]WHYWOULDYOUEVENARGUE [スコア非表示]  (0子コメント)

        It will take more than just a few million years for andromeda to look that big.

        [–]brodins_raven [スコア非表示]  (0子コメント)

        Yeah I have often seen Andromeda in the future images...people might have just taken this out of context and propagated it?

        [–]tombh [スコア非表示]  (1子コメント)

        Original creator of said image here. I totally support this. I had absolutely no idea my image was going to be so popular and so I did the scaling purely by eye. I'm not surprised I was a little bit off.

        [–]encephlavator [スコア非表示]  (0子コメント)

        Hey, thanks for chiming in. It's an awesome pic and you're kind of famous now. You did see the Phil Plait article, right?

        [–]Skafsgaard [スコア非表示]  (0子コメント)

        Man... I feel like this gif needs some dubstep music.

        [–]Calibas [スコア非表示]  (0子コメント)

        Apparently we're getting closer to Andromeda, so just give it a hundred million years or so and the first image will be accurate.

        [–]astrolitterbox [スコア非表示]  (2子コメント)

        Actually, you're not exactly right. It all boils down to the definition of the size of a galaxy, which is hard to do -- they're fuzzy objects without sharp limits as, say, the Moon. If your eyes were 4m wide CCD cameras, you could see all the faint outskirts of Andromeda and remnants of destroyed satellites around it. In such a case, it would look about 3 times larger than in your image and take up a fair area of the sky! See the image here: http://cosmic-horizons.blogspot.it/2014/01/just-how-big-is-andromeda.html

        Source: PhD in astrophysics.

        [–]RobHag [スコア非表示]  (0子コメント)

        Masters degree in astrophysics here. I completely agree with you.

        Roughly, the density of stars in a galaxy disc drops off exponentially with distance from the centre. The diameter of Andromeda simply boils down to a question of definition. There is no "what we usually call Andromeda", the stars continue much further out than the astronomical definition.

        The visual Andromeda disc would appear wider and wider if you just increase the light sensitivity of your imaging device.

        TL;DR this guy's comment should be at the top because it's true.

        コメントをもっと表示する (1 返事)

          [–]ZipZowie [スコア非表示]  (0子コメント)

          All those wasted years!!! Gone! Simply gone!

          (Actually....thank you. ;)

          [–]thelidpatrick [スコア非表示]  (1子コメント)

          I wish I was born in the time where Andromeda would actually be visible during the day and at night cause wow that would be mesmerizing.

          [–]Randy__Bobandy [スコア非表示]  (1子コメント)

          Because I'm such a nerd, when I first heard of the 8.5x number, I tried calculating it out myself. Took the distance and diameter of Andromeda, and it didn't match the supposed 8.5x figure. I always figured I was doing something wrong but I'm glad to know that they were wrong.

          [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

          That's why I included the pixel coordinates in my images, so people could double check the pixel dimensions. :)

          There is of course some fudge in the numbers because defining the measurable edges of a galaxy is pretty difficult. I got my angular diameters from Wikipedia rather than calculating them myself. I think they should be a pretty good approximation.

          [–]SamTheCameraMan [スコア非表示]  (0子コメント)

          Misinformation can be quite troublesome, so thanks for this OP!

          [–]nostromorebel [スコア非表示]  (14子コメント)

          I'm nowhere near as knowledgeable as you in this department but I'd like to offer food for thought.

          The first thing I thought of was relativity. Depending on the time of year, the distance from the horizon, even the moon's actual distance can all affect it's apparent size. Admittedly, I don't know exactly how much.

          Second was photography related. The focal length of the lens can drastically affect the sizes of objects at varying distances; e.g. a telephoto lens makes those pictures of a house on a mountain with an unnaturally massive moon looming behind it and a wide angle lens would make both nearly pin points in a sea of sky, mountain, and ground. 35mm is what we consider closest to what we observe with our own eyes. I'm shabby, but this photo appears to be somewhere near that, possibly closer to 24-28mm.

          These seem minor, and possibly like things you've likely considered, but together they can make the approximation involved a bit tricky.

          I appreciate your effort. I find stuff like this truly interesting.

          [–]thispun [スコア非表示]  (6子コメント)

          I just want to point out that the moon's distance to the horizon has no effect on its size on pictures. We only perceive it while looking at the actual moon ourselves. It's called the moon illusion.

          [–]CynicalYetOptimistic [スコア非表示]  (0子コメント)

          It's a magic trick Gob, not an illusion.

          [–]dhelfr [スコア非表示]  (4子コメント)

          I've heard this to be true, and it makes 100% sense to me. I just have such a hard time believing it. I have some trouble accepting just how bad our eyes are at telling how big something is unless we have a reference object,

          [–]DiskPidge [スコア非表示]  (0子コメント)

          I don't know if it helps, but think of it this way: it's not our eyes that are bad at perceiving it, it's our brains that are bad at interpreting the information given by our eyes - our brain often re-interprets information it doesn't need to.

          [–]Lawant [スコア非表示]  (0子コメント)

          Our brains and eyesight did not evolve to correctly perceive the world, but to perceive it most effectively.

          [–]TheLeisureClass [スコア非表示]  (0子コメント)

          When I young someone demonstrated this to me very effectively: Hold your hand out at arms length and compare the size of the moon to a fixed size reference object such as a coin or your thumb. Do this when it is near the horizon and again when it is high above in the sky. This will quickly show that it is indeed unchanged in size as it moves across our sky.

          [–]sylban [スコア非表示]  (0子コメント)

          Why would you have a hard time believing that optics and optical processing neurology originally evolved to see undewater and then later crudely adapted for spotting predators in tall grass only a million years ago might not be optimally suited for accurately gauging the size and distance of cosmic objects?

          This attitude seems typical of those who assume some kind of perfection in the human animal, and seem surprised to learn how imperfect it really is. We are -- at best -- physically and neurologically optimised to how we lived a million years ago -- a tick of the second hand in evolutionary terms. The rise of human civilisation (which started 10-12,000 years ago) is a vanishing instant on that scale, and will have little or no determining effect on the changes in our genetics and adaptations of the last eight or ten million years (the approximate age of our genus, depending on how you reckon it). And even that's being very forgiving, if you consider things such as how our knees and respiratory system are still not ideally adapted to bipedalism, and probably won't be for another few million years.

          Being able to accurately gauge the size of the moon has absolutely no evolutionary advantage, so there's no reason we would ever have developed it. Why should it surprise anyone that we might be bad at that? Our eyes are still trying to adapt to seeing in air instead of water, and that's an actual survival adaptation. Seeing things in space confers no survival benefit, so that's not even on the list of things to get around to.

          Humans are in fact bad at many, many things, and the more you learn about that, the more you can appreciate your own shortcomings as a human being and avoid the countless ways we fool ourselves. Presuming we're 'smart enough' to deal with all that is one of the biggest ways we get ourselves and each other into trouble.

          [–]Sneaky_Weazel [スコア非表示]  (1子コメント)

          Point 2 is caused by relative distance to the observer. Celestial objects are far enough away that their size compared to each other is not affected.

          [–]nostromorebel [スコア非表示]  (0子コメント)

          True. I was more thinking about the moon's size, but since the galaxy would scale with the moon's size, the real difference lies only between the two. Infinity wins.

          [–]DenebVegaAltair [スコア非表示]  (0子コメント)

          The focal length won't change the apparent size of the moon. Changing the focal length is merely the same as zooming in. If you were to travel towards the moon, then then the ratio between the size of the moon and the Andromeda Galaxy will increase.

          [–]goneinseconds [スコア非表示]  (2子コメント)

          Your points are great, however, 50mm is the closest to what we see with our own eyes. 35mm is considered somewhat of a wide angle.

          [–]FogItNozzel [スコア非表示]  (0子コメント)

          He could be talking about 35mm on a crop sensor camera. Those are typically 1.5 or 1.6x crops, putting 35mm at roughly 50mm, effectively.

          [–]Iwasborninafactory_ [スコア非表示]  (0子コメント)

          50mm on a full frame 35mm.

          35mm on an APS size frame is about the same zoom. On an APS sensor, 50mm is actually a good bit of zoom.

          [–]omv [スコア非表示]  (0子コメント)

          I think OP addresses this issue by saying the average angular diameter of the moon, but even if OP didn't, the largest super moon we see is only 14% larger than a standard full moon. OP is saying the original post exaggerated the size of the galaxy by 3 moon diameters, which would overpower the effect no matter when you took your example moon diameter. Also, although it may be possible to change the percieved size of an object using focal length, if the point was to simulate what the galaxy would look like in the night sky, why would you?

          [–]winerice [スコア非表示]  (3子コメント)

          Not trolling, but why so serious about such a minor detail?

          [–]SashaTheBOLD [スコア非表示]  (3子コメント)

          Maybe the other photo is Andromeda at its perigee.

          [–]dumptrucks [スコア非表示]  (2子コメント)

          I'm hoping to assume your joking.

          [–]SashaTheBOLD [スコア非表示]  (1子コメント)

          That sounds reasonable enough.

          Have an upvote for assuming I'm not a mouth-breathing imbecile!

          [–]dumptrucks [スコア非表示]  (0子コメント)

          Holy shit, I just re-read my comment. I grammared once, but that was long ago.

          [–]TangledupinBluegrass [スコア非表示]  (0子コメント)

          When I saw that image, I knew to wait for the edit.

          [–]WalrusTheSailor [スコア非表示]  (5子コメント)

          So, where does this guy make a mistake?

          [–]GSlayerBrian[S] [スコア非表示]  (4子コメント)

          His math is perfectly fine. He just completely skips comparing the relative sizes of the objects in the referenced image.

          [–]encephlavator [スコア非表示]  (3子コメント)

          We need to contact Phil Plait and have him rehash this. I can't find an email link at his page though.

          [–]GSlayerBrian[S] [スコア非表示]  (2子コメント)

          Na I don't feel that it's that important (and indeed there are a couple of people actually showing hostility to me about my correction). I just wanted to do my small part to contribute to everyone hopefully having a slightly more accurate idea of the Cosmos.

          [–]tombh [スコア非表示]  (1子コメント)

          Original creator of the image here. Sorry to hear you're getting grief. I totally support the correction!

          [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

          Thank you, I'm glad you feel that way! I of course meant no offense by this - it had always just been a minor thing that bugged me and I finally wanted to get it out there and corrected once and for all. Granted my version still isn't perfect, not that I'm claiming it is (and some folks have seen fit to be rather vocal against my version for various reasons), but to reiterate and rephrase what I've said in a couple of other comments: It behooves each of us as scientists to ensure our data is as correct as it can be. Even if it seems trivial to some, there's no harm in making things more accurate. If it has even a small contribution to bettering our understanding of our Universe, then it can only be a good thing.

          [–]ickN [スコア非表示]  (0子コメント)

          Thanks for fact checking, it doesn't happen enough. I fell for the Bruce Lee ping pong ad a couple of weeks ago...darn internet!

          Either way, I wish we could really see that with naked eye.

          [–]JuntaEx [スコア非表示]  (6子コメント)

          Can someone explain what is happening here? Why do we see that galaxy so huge in the sky even in the corrected image?

          [–]GSlayerBrian[S] [スコア非表示]  (5子コメント)

          Because it is indeed just that enormous. To put it very plainly, the Moon is smaller, but closer. Andromeda is larger, but farther away. But despite its truly immense distance, it is still so gigantic that from our point of view it is still takes up much more sky than the Moon does.

          [–]JuntaEx [スコア非表示]  (4子コメント)

          Is it possible to see it, exactly like that? Or does light pollution block the view or something?

          [–]sylban [スコア非表示]  (0子コメント)

          Not exactly like that, no. It is many times fainter than that. But if it was bright enough to easily see, that's how it would look to us.

          [–]GSlayerBrian[S] [スコア非表示]  (2子コメント)

          I know more about cosmology than I know of anatomy, so my explanation will be simplified and possibly inaccurate - I defer a more in-depth explanation to someone more qualified. The gist of it is that our eyes are just incapable of absorbing enough light to perceive Andromeda as it is in the image. It requires a long exposure time to gather enough light for the galaxy to be seen in that manner.

          But if you could train a camera in a portion of the sky with both the Moon and Andromeda in it (I don't know if that ever happens), and you took a long enough exposure, then you could have a photograph that looks very much like the one in question, without any image manipulation.

          [–]JuntaEx [スコア非表示]  (1子コメント)

          Ok that makes sense. However, if this is the case, why can't we see it at night? Seems that an object that size should project enough light in the night sky (assuming little or no light pollution) for it to be visible?

          [–]Hahahahahaga [スコア非表示]  (0子コメント)

          Are you sure you accounted for the lunar maximum?

          [–]yusbarrett [スコア非表示]  (0子コメント)

          I was so amazed with the former picture,you blew up my illusion! Stupid scientific correctness! Now I understand why religion hates you so much!!

          [–]Fabb4eyes [スコア非表示]  (0子コメント)

          the Andromeda galaxy is on a collision course with our Milky Way? True or false?

          [–]KE55 [スコア非表示]  (1子コメント)

          Perhaps a dumb question, but rather than use these photoshopped images isn't it possible to use a telescope to capture both the Moon and Andromeda in the same picture?

          [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

          It actually would not require a telescope, only a good camera with long and/or many exposures and on a tracking gimbal.

          I'm checking right now to see if the Moon ever gets close to Andromeda in the sky to facilitate such an opportunity, and will get back to you in a little bit.

          That said, I worry that with enough exposure to capture Andromeda, the brightness of the moon would be too great and would overexpose the image. So something fancy might need to be done - I just don't know enough about photography to know if it would be possible.

          Edit: It looks like the Moon and Andromeda will be within about 30° of each other tonight, so it would likely be possible to capture both of them in the same image if a skilled astrophotographer was up to the task. As I said I'm not sure if the Moon being so bright compared to Andromeda would wash it out, but they can at least be in the same portion of sky at the same time.

          [–]caessa_ [スコア非表示]  (0子コメント)

          I just came from /r/MassEffect and took a double take when I saw Andromeda in the title...

          [–]PM-ME-YOUR-THOUGHTS- [スコア非表示]  (0子コメント)

          I too, would like to stop the circulation of this tragic misinformation.

          [–]aterrorcatsandwich [スコア非表示]  (0子コメント)

          Is there a word for the simultaneous sense of significance and insignificance the beauty of this galaxy conjures up?

          [–]Mrpleaze01 [スコア非表示]  (0子コメント)

          It is simply because, not All things man could see. Sometimes you just have to crossed your own boundaries,,, of illusion! That's where I came from

          [–]condemn1000 [スコア非表示]  (1子コメント)

          Now do it again comparing the nearest and farthest point in the moon's elliptical orbit. For science ;)

          [–]mortiphago [スコア非表示]  (0子コメント)

          which leads me to ask:

          how close should andromeda have to be to be as bright as in the picture?

          and the inverse:

          how bright would it actually look if it were 8.5 moon diameters big.

          [–]pogrmman [スコア非表示]  (0子コメント)

          What I don't like about this image is that it doesn't look like what the galaxy looks like if it were brighter. This is an ultraviolet image. If it were brighter, it would look like a bigger fuzzy patch, not like this. I don't even think you'd be able to see the dust lanes with the naked eye.

          [–]Levitacus [スコア非表示]  (0子コメント)

          It's not as bad as the "Tonight Mars will be as big as the moon in the night sky" misinformation posts. If Mars ever gets that big, we're dead.

          [–]A_of [スコア非表示]  (0子コメント)

          Thanks for the correction.
          I must say that the corrected image is still impressive. To think that Andromeda is so large that even at 2.5 million light-years away it looks bigger than the moon in the night sky is mind boggling.

          [–]Bounkass [スコア非表示]  (0子コメント)

          Is the andromeda galaxy really that big if it were brighter? Wow. I wouldn't mind looking at thay all night.

          [–]2dayoldbread [スコア非表示]  (0子コメント)

          I like the first one. Its got more pop. Maybe a Saturn in there too? Saturn has rings. People like rings. Rings have pop factor too. Needs to be just a little smaller than the moon though. Since its further away.

          [–]TwoPhotons [スコア非表示]  (0子コメント)

          Thank you very much for doing this. The only people who are missing the big picture are the people who are calling you out for missing the big picture. Science is quite simple - it's about getting as close as possible to the truth, not distorting the facts to create some sort of "effect". I wonder how big one could make that galaxy before people would say "Hang on a minute, this doesn't look right". It's stupid. Good job OP. :D

          [–]fugeeneer [スコア非表示]  (3子コメント)

          Now do it again comparing the nearest and farthest point in the moon's elliptical orbit. For science ;)

          [–]encephlavator [スコア非表示]  (1子コメント)

          The difference in apparent size of The Moon between perigee and apogee is 12 to 14%. At the scale of Andromeda vs The Moon pics, it would be an unnoticeable single pixel of width.

          Somewhat relevant: Supermoons Are Super Dumb

          [–]gorocz [スコア非表示]  (0子コメント)

          Does that page prevent anyone else from closing it with CTRL+W?

          [–]GSlayerBrian[S] [スコア非表示]  (0子コメント)

          Just for you (and science!)

          [–]JMile69 [スコア非表示]  (0子コメント)

          I would like to see an end to the misnomer that at some point in the distant future it will be all huge and bright on the sky as it approaches the Milky Way. Surface brightness is a function of area on the sky. As it approaches, it's area grows and it's surface brightness per solid angle decreases. It will be just as feint 4 billion years from now, as it is today. Certainly no more visible than the Milky Way is.

          [–]timephotographer [スコア非表示]  (0子コメント)

          Actually, I took this photo in the future when Andromeda is a lot closer to Earth, so it is technically to the correct scale in the year 105105.

          [–]stromm [スコア非表示]  (1子コメント)

          So you think its OK to circulate one incorrect photo, but not another?

          [–]neihuffda [スコア非表示]  (0子コメント)

          The one with the correct size isn't incorrect, it's an illustration with the condition "if it was brighter", not "if it were bigger and brighter". The former is way more interesting, because 8.5 times the angular diameter of the seems to be just an arbitrary number. In other words, OP isn't circulating another incorrect photo.

          [–]Pleego7 [スコア非表示]  (0子コメント)

          So is the corrected image our view of the andromeda galaxy from earth?

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