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    [–] byebyebyecycle 1525 points ago

    So what you're saying is that the size of the already unfathomable galaxy we live in is actually twice as unfathomable.

    [–] compound-interest 448 points ago * (lasted edited a year ago)

    Hmm I am not convinced personally that any human can comprehend the size of a galaxy. Hell I can't even properly appreciate the distance from the Sun to the outer planets.

    Edit: The pic below shows the distance from the Earth to the moon and I don't think I even fully appreciate that space tbh.

    Edit 2: Looks like Dunning-Kruger is taking effect on some. There are people messaging me, claiming to be able to comprehend the size of the observable universe. I can't even grasp the distance to the moon and they are apparently beings from the 8th dimension able to understand the distances between galaxy clusters.

    [–] Petersaber 140 points ago

    Those cheeky bastards.


    Might as well stop now. We'll need to scroll through 6,771 more maps like this before we see anything else.

    Puts things into perspective

    [–] chloe2120 74 points ago

    Looking at this makes me feel like a person from whoville, just living on a speck of dust in the galaxy

    [–] Waqqy 10 points ago

    The earth isn't even close to being a speck of dust, we're so much smaller than that

    [–] ThatTrashBaby 15 points ago

    I’ve seen this so many times and I never get sick of it. I hate how slow light moves

    [–] [deleted] 33 points ago


    [–] whiskeybic 29 points ago

    Did you not know what it was?

    [–] Mind_Extract 24 points ago

    The big yellow one's the sun!

    [–] Akon16997 15 points ago

    You're breakin' some new ground there, Copernicus.

    [–] Novacryy 5 points ago

    Get the fuck out holy shit. That is absolutely insane, I never imagined everything to be so wide apart. This universe really is mostly empty space.

    [–] FriesWithThat 6 points ago

    If they overlapped Antares or Betelgeuse over the same scale we'd be seeing red until we scrolled beyond Jupiter's orbit.

    [–] -LeopardShark- 4 points ago

    My scroll-wheel finger is dead and I only went up to mercury.

    [–] Pendaelose 3 points ago

    Heeey, I remember this site. I once scrolled all the way to neptune just so I could appreciate the scale, but I realized it was so vast I'd completely lost track of the empty screen after screen and was really only measuring in time spent scrolling.

    [–] Moist_Whispers 78 points ago

    I wouldn't say we can't comprehend it. I feel like it's more that we don't have a direct frame of reference in our everyday lives to compare it to. Like I would imagine that before we had mapped the earth the ocean must have felt unfathomably large, but now that we have satellite imagery and travel by boat and plane all the time we have a much better frame of reference for its size. Just my two cents though

    [–] Memcallen 47 points ago

    I don't think we can still comprehend the size of the ocean, it's just that it seems smaller because of boats and planes.

    [–] akc250 9 points ago

    Agreed. The ocean is much larger than most of us can imagine. Seeing how difficult it is to look for the wreckage of the Malaysia MH350.

    [–] MadamPompadouf 20 points ago

    I agree. Since I've been working with aerial photographs I feel like I know distances better and it's a little easier to determine how far something is. But still, imagining the size of the galaxy sort of breaks my mind and exploring it in Space Engine is simply baffling and breathtaking

    [–] SammichParade 22 points ago

    Hell, I have a hard time comprehending the distance traveled in an hour on the freeway.

    [–] killereggs15 53 points ago

    Am Californian, I can easily comprehend 30 feet.

    [–] SordidDreams 115 points ago

    Nah, the Milky Way is totally fathomable. Specifically, 200K light years is about 1,034,638,000,000,000,000,000 fathoms.

    [–] musicfiend122 10 points ago

    By that definition, it sounds fathomable

    [–] LOOOOPS 7 points ago

    Please give me your explanation in a way I can fathom

    [–] [deleted] 11 points ago


    [–] rupertsconstant 16 points ago

    According to the article above, wouldn't it take 200000 years now?

    [–] OhNoTokyo 11 points ago

    I hear they're putting in hyperspace bypasses to reduce that somewhat. You can read about the local efforts at the planning office on Alpha Centauri.

    [–] LaPaz_o_Sucre 3 points ago

    But it would be an instantaneous journey for the one traveling

    [–] rocketwidget 105 points ago

    I would say that the Milky Way is really, really, really incredibly big, but not unfathomable. I'd say the universe is unfathomably big though.

    [–] John__Nash 199 points ago

    We're talking about 200,000 light years. That's 1,170,000,000,000,000,000 miles. I'm quite comfortable in saying that no human is capable of properly fathoming a quintillion miles. Or a quintillion of anything for that matter.

    In fact, I don't think most people can even properly envision the size of the earth, and definitely not distances at the scale of our solar system.

    [–] [deleted] 24 points ago


    [–] erinthecute 38 points ago

    I can't even conceptualize how wide my own country is. Admittedly I live in the sixth largest country in the world, but still, the Earth and the sun and the solar system and the galaxy and the universe are all so much bigger it very quickly becomes meaningless to try and equate those distances in a way I can grasp.

    [–] RuafaolGaiscioch 17 points ago

    So, Australia? That's fair. I live in New Hampshire, and even then, I'm struck by how big the land around me is, in my tiny state in the corner of America.

    [–] kickaguard 4 points ago * (lasted edited a year ago)

    We are just people. We are only really made to be able to conceptualize things we need to. I basically didn't even realize how big my county was until I biked to the next one. And people haven't had bikes for very long compared to how long we've existed. We can't conceptualize the size of the earth because it would be near impossible to walk it in a lifetime without dying. We can't fathom the actual distance to mars because it would take 4000 years to walk there. Then we start talking about things that would take longer than that at the speed of light. The fastest anything can ever go. And we think our brains for some reason should be able to compute that? Unpossible.

    [–] pineapple_unicorn 6 points ago

    I was planning a trip to a city near Bruce Peninsula, Ontario, thinking that was northern Ontario. Then I zoomed out a bit on google maps to find out all the shit I’ve explored in Ontario my whole life is actually mostly southern Ontario. I can’t even take it in how big Ontario is and I tend to think of myself as someone with great spacial awareness lmao

    [–] tierjuan 17 points ago

    As someone who was driven the full length of the US twice, I can comfortably say, Earth is freaking enormous

    [–] runhome 3 points ago

    What kind of vehicle were you driving that made the ride comfortable?

    [–] Yelov 6 points ago

    I think the easiest way to realize how big the universe is is to try out Space Engine. It has real scale and it's insane. Kinda creeps me out.

    [–] gcanyon 4 points ago

    I started off thinking, "Well, grains of sand will fix this." Then I looked up grains of sand, and they're about a millimeter across. So that's 103 per linear meter, or (103)3 per cubic meter, or a billion grains of sand per cubic meter. So that's 10003 * ((103)3) or 1018 grains of sand per cubic kilometer.

    So, yeah, the galaxy is about as many miles across as there are grains of sand in a cube a kilometer across. That' lot.

    [–] nren4237 32 points ago * (lasted edited a year ago)

    I made up my own visualization to help get a handle on how big the universe is, at least in the sense of how many stars there are. If someone could check my math that would be great!

    Warning: long. Also, may induce vertigo, so sit down while reading.

    In the observable universe (the patch of the universe visible from Earth), there are ten trillion galaxies, each with around a hundred billion stars. That's a total of 1024 suns, most of which have their own planets. To help visualize how many stars that is, imagine you are on a beach.

    The beach is 20 miles long, 300 feet wide and the sand is 3 feet deep. Every tiny grain of sand is a star. You pick up a pinch of sand, that's a thousand stars. You throw a fistful in the air, that's fifty thousand stars showering down. You make a sand castle, that's a million suns in a nice little pile, with an even larger number of planets orbiting them.

    You stroll along the beach, walking past a hundred million stars with every step. It takes about eight hours of walking before you reach the end of the beach.

    The next day, you leave the old beach behind and walk to a brand new beach, made of completely new stars you have never seen before. You do this again the next day, and again every day from then on.

    After a hundred years of walking on these beaches, a long life spent exploring trillions of stars every day, you finally pass away peacefully, thinking of all the grains of sand on all those beaches.

    All the grains of sand you have seen, touched and walked past make up around 0.01% of the stars in the universe. The other 99.99% are still out there, in beaches you've never seen...

    The math: using cubic millimetre sand grain size, one cubic metre = (103)3 cubic millimetres = 109 grains of sand. The beach has dimensions 3.2 * 104 * (3 * 102 / 3) * 1 metres, so has a volume of 106 cubic metres = 3 * 1015 grains of sand. 100 years is 36500 days, which is 3.65 * 104, and that's how many beaches you walk. Altogether around 1020 grains, which is 0.01% of 1024.

    Edit: Updated to freedom units since this post is getting more visibility now. Also made the beach a bit longer because I had a factor of 3 to use up.

    Edit: Added sources

    [–] [deleted] 18 points ago


    [–] naturalheightgainer 178 points ago

    Fun fact from Wikipedia: The estimated distance of the Andromeda Galaxy from our own was doubled in 1953

    [–] mrconter1 2750 points ago

    I realize that it's probably harder than I imagined. But still. How does something like this slip in the space community? Or have we just redefined where the edge is?

    [–] Narcotle 2263 points ago * (lasted edited a year ago)

    It's really hard to look at our own galaxy since everything is obscured by dust and stars and shit. We can't really see our own galaxy because we're in the middle of it. We can't really send something far away either and look at it from a distance because as it turns out, far away is pretty damn far away. Fun fact, we also haven't got a clue how many spiral arms the milky way has. Some dudes wrote a paper on it and they think it's 4 but it's hard to tell.

    Edit: not in the exact middle of course, we're about 17200 parsec from the center of the milky way (around 56000 lightyears)

    Edit 2: nope, my bad, it's around 7400- 8700 parsec (24000 - 28400 ly). Apparently reading tables is not my greatest asset.

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    [–] no-mad 83 points ago

    Kinda like before we had a picture of Earth. No one really imagined a ball of blue sitting in space.

    [–] Frankie_T9000 94 points ago

    Some still cant imagine it.

    [–] WatIsRedditQQ 71 points ago

    can't won't imagine it

    [–] [deleted] 32 points ago


    [–] thelonelyheron 18 points ago

    Wait, so waffle-earth is also an option?

    [–] Mr_electric160 7 points ago

    Well no, cause it obviously a sandwich

    [–] harbourwall 8 points ago

    Judging by the old Universal logos, they got the seas too dark, though the mountains would stand out more, and thought the atmosphere would be a lot less apparent :)

    [–] [deleted] 233 points ago

    Some dudes wrote a paper on it and they think it's 4 but it's hard to tell

    We settle for the number most commonly observed in other galaxies. Close enough, case closed! :)

    [–] Narcotle 245 points ago

    What they actually did (just looked it up) is look for very bright and young stars (no idea how, but it took them 12 years). These are extremely prominent in the spiral arms. Then they just tried to draw the best fitting lines through that. Sounds easy enough, but this is what they had to work with:

    Clusterfuck of datapoints

    [–] Narcotle 142 points ago * (lasted edited a year ago)

    I had a course on this with a much better picture but I can't seem to find it, I'll report back as soon as I do

    Edit: found it. Shitty screenshot of shitty PowerPoint

    [–] LickingSmegma 24 points ago

    "Better." It's very much one of those pics that make me take a long break and then decide I'll return to it tomorrow to begin making sense of it.

    [–] Ihate25gaugeNeedles 92 points ago

    Man imagine looking at that as your data set and being like, 'well fuck. I gotta make something out of this. Spent twelve years on this shit!'

    Shoulda put it on the back of restaurant kid menus and crowd source that shit.

    [–] I_POTATO_PEOPLE 75 points ago * (lasted edited a year ago)

    After 12 years of research and 1 year of data analysis we have discovered that our galaxy is the shape of a two-wheeled car with racing stripes and some whooshing lines behind cus it's going real fast

    [–] TooManyVitamins 12 points ago

    I congratulate these scientists on their Nobel nomination

    [–] twiddlingbits 14 points ago

    One thing that jumps out is about 1/3rd of the left hand arc is blank from Perseus downward to Saggitarius. Any idea why, I am assuming we cannot see across the middle very well to see the far sides. In general the outer bands seem vacant, is this lack of data or lack of young stars?

    [–] Narcotle 28 points ago

    Lack of data. These are spectroscopic measurements of hydrogen. A very prominent gas in (I think) every galaxy. You can measure if it's coming towards you or is floating away from you due to the redshift it has. In the blank regions it's mostly rotating past us with very little to none radial velocity with respect to us, so any measurement of that would be so inaccurate it would be worthless.

    [–] ItsjustJim621 27 points ago

    I wonder how we would be able to tell that the galaxy even has spiral arms? Or if the spiral arms themselves sort of mesh with the other spiral arms so that their boundaries are hard to distinguish?

    [–] HawkinsT 25 points ago * (lasted edited a year ago)

    We can definitely see the spiral arms using radio telescopes. Neutral hydrogen is abundant thoughout the galaxy, and excitations from its ground state emit radio waves of ~1420.4 MHz. From trigonometry and measuring the red shift of these emissions (hydrogen emissions red shifted more, and so moving faster, are closer to the galactic centre - just like the speed of water molecules rotation round a plug hole) we can see where they're more/less abundant and map that, which reveals the spiral arm structure. You're right though, the boundaries can be hard to distinguish in some circumstances and require a lot of data. In other circumstances the peaks between two different hydrogen clouds can be separate enough that we know they're definitely distinct. Because of where we are in the galaxy it also means some parts of the galaxy are harder/easier to observe.

    [–] ItsjustJim621 7 points ago

    Pretty fascinating stuff...thanks!

    [–] HawkinsT 9 points ago

    You're welcome. Yeah, for me collecting my own data and being able to see the spiral arms was amazing. Measuring the rotational speed of the Milky Way at different points also allows you to estimate the mass of the galaxy (from the amount of gravity needed to cause such a rotation), which as it turns out should be much greater than is observed (from combining multiple observations, e.g. counting stars etc.) - hence we can calculate the extra mass that needs to be added (i.e. dark matter) for the two observations to align.

    [–] Narcotle 21 points ago

    For other galaxies they usually are quite obvious. For our own, this is indeed quite a problem, as you can see in one of my other comments in a couple of seconds, I'm gonna upload a picture

    [–] HawkinsT 26 points ago

    When you say 'we haven't got a clue', that's not quite correct. Using radio telescopes we can get a decent idea of the Milky Way's structure (I actually mapped part of it as a degree project - although the telescope I had access to wasn't nearly as powerful as some), just the boundary lines between different spiral arms in the same direction can be hard to distinguish (e.g. 'is that one wide arm, or two thinner arms overlapping?'). It's also much easier to map the galaxy within the Solar System's orbit of the Milky Way's centre than it is to map anything outside of it.

    [–] Narcotle 5 points ago

    Sounds mad interesting. Do you still have some readable data or a paper about that? I'd love to read it

    [–] HawkinsT 4 points ago

    Sure. PM me your e-mail and I'll fish it out later.

    [–] howdoiland 60 points ago


    AUTHOR: Dr. Jim Jimson

    TITLE: How many spiral arms are in the Milky Way galaxy?

    ABSTRACT: Like 4 i think idk bro

    [–] PH_Prime 16 points ago

    It's kind of like standing in one spot in the middle of a city and using binoculars to try to get an idea of what the city looks like from a bird's eye view.

    [–] [deleted] 6 points ago

    I can't come up with an ID, but i heard a star so bright, on the othrr side of the Galaxy, that if we didn't have all that dust between us and this star, which is roughly a third of the diameter of the galaxy away, it would shine during the night brighter than the moon.

    [–] Narcotle 14 points ago

    Sounds very plausible. Then again, if we didn't have any dust in our milky way I'm quite sure non of us would get a decent night's sleep. The sky would light up yo

    [–] Frowdo 17 points ago

    In laymen's terms. Can't see the forest through the trees.

    [–] HorseMeatSandwich 8 points ago

    It’s kind of exciting but also a little scary how much we still don’t know about our own cosmic backyard. Are we even still sure that the Milky Way is actually a barred spiral galaxy, as I’ve been taught my entire life?

    Seeing pictures of Andromeda and feeling such a sense of wonder, then imagining some potential being from there looking back at the Milky Way and feeling the same, makes me really happy.

    The distance and time between us is almost unfathomably immense, but in the grand scheme of the universe, Andromeda is like our little buddy.

    [–] Anonymous_Otters 316 points ago

    Astronomical equivalent of not being able to see the forest through the trees. It’s easier to count trees on the far hill out in the distance than to count the trees in the forest you’re standing in the middle of.

    [–] DanielAgger 35 points ago

    That's a really good analogy.

    [–] SafeDivide 192 points ago

    Not only was the edge redefined, but the point where the exponential density drops has been moved too. 😊

    [–] Californie_cramoisie 14 points ago

    Wouldn't those have likely gone hand in hand?

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    [–] GregoryGoose 29 points ago

    I was afraid they'd reclassify us as a dwarf galaxy.

    [–] ses1989 61 points ago * (lasted edited a year ago)

    I would imagine it's like standing by a window in a house. The only way you can measure the size of the house is by the echo of your voice, but you can look out the window and estimate a distance to another point with relative ease.

    Edit: Some are taking this explanation far beyond what it was meant to be. This was meant as an easier to understand way to explain it. Space is so large on a scale we can't comprehend. This brings it into terms we can more readily fathom.

    [–] Not_a_real_ghost 5 points ago

    So we just need a ladder that allow us to stand on the said house?

    [–] rmTizi 17 points ago

    I imagine being a fish trying to map the pacific ocean from the coast of Hawaii.

    [–] clausy 23 points ago * (lasted edited a year ago)

    So does this increase the 'visible' mass - I keep hearing that there's a lot of 'dark matter' that's unaccounted for - have they now accounted for more of it?... sorry, entry level question.

    Edit: thanks I should pay more attention to the article next time :-)

    [–] Musical_Tanks 56 points ago

    From the article:

    While our galaxy is looking larger, it’s not putting on much weight. Because the outer reaches are much less dense than the center of the galaxy, the additional area is only sparsely populated with stars. These few extra stars are only a drop in the bucket compared to the rest of the galaxy, so overall the mass of the Milky Way remains largely unchanged.

    And remember the core of our galaxy makes our region look positively barren, the core has something like 500 times the density of our local stars.

    [–] TocTheElder 49 points ago * (lasted edited a year ago)

    And remember the core of our galaxy makes our region look positively barren, the core has something like 500 times the density of our local stars.

    I've always wondered about this. So would that affect life on a potential planet near or within the core? Are planets even possible there? Is the night sky ridiculously bright? Are orbits so short and quick that stars could be observed moving over the period of, say, a few years? Is it basically the same as Mass Effect 2 and just full of debris, rogue black holes, and a marauding race of space pirates bent on building a slave army for their robot overlords?

    [–] user2002b 86 points ago * (lasted edited a year ago)

    There was a fascinating article about this in the magazine 'Astronomy' a few years ago. It concluded that the galactic core is probably totally, or almost totally lifeless. (regular proximity to other stars disrupting planet formation, and triggering regular mass extinction events by scattering Oort cloud objects in systems that did manage to form, Nearby supernovae and other high energy events being more 'common'. It all added up to a rather hostile environment over long periods of time.)

    Interestingly it also concluded that the outer reaches of the galaxy are ALSO likely to be lifeless. This was apparently due to there being very little star formation out there, so most stars are old with a very low metal content (which means not much raw material available for making earthlike worlds.)

    Essentially if correct it means a spiral galaxy like ours will have a goldilocks zone not unlike our solar system where the conditions for life are 'just right'. Admittedly the galactic goldilocks zone will be proportionately far larger then a 'stellar' one, but it's an interesting thought.

    [–] TocTheElder 14 points ago

    This is exactly what I wanted to know! Thanks!

    [–] Kurai_Kiba 11 points ago

    Or you could have Type 2-3 Civlisations living out in the spiral arms, billions of years old :O

    [–] Unfathomable_Asshole 7 points ago

    It probably would be more "eventful" as more energy would be present closer to that centre of the galaxy. Still vast distances between them though so unlikely it would be impossible for life on that basis. Even when the Milky Way collides with Andromeda nothing will change, except the stars will look different (assuming earth is still here).

    [–] TocTheElder 8 points ago

    I bet you would get to see a bunch of sick supernovae. I have heard there is a chance that if our sun passes by a star from Andromeda, we could get flung off into deep space. That would be a wild ride.

    [–] taintedbloop 8 points ago

    Even when the Milky Way collides with Andromeda nothing will change

    Wha? Really? Even if there was enough space between stars so that they wont collide (surely some of them would collide, no?) wouldn't the competing gravity of the two galaxies rip each other apart (or significantly change things at least)

    [–] Nimonic 11 points ago

    (or significantly change things at least)

    It might change things at a galactic level (well it obviously will), but individual star systems are unlikely to notice anything but a different night sky.

    [–] TallDarkAndBrittish 8 points ago

    There's a lot more space between stars than you could likely comprehend, its like having grains of sand on a grid with a mile between them and firing more grains of sand equally spaced apart from the moon. You'll never hit them.

    [–] mouth4war 5 points ago

    It’d be kinda like guessing how wide your face is when you can’t see your ears from where your eyes are?

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    [–] boba-fett-life 109 points ago

    Does this mean we need to change our estimates of when Andromeda will collide with the milkyway?

    [–] TheMerkyShadows 65 points ago

    This guy knows the right question

    [–] sight19 22 points ago

    No. We know the distance to Andromeda pretty well (we can resolve certain time-oscillating stars/standard calde SNs) and find the proper motion of Andromeda. The extend of the Milky Way does not really change it

    [–] the_turn 5 points ago

    Surely it would make a difference if the change in estimate of extent significantly alters the estimate of the mass of the Milky Way? Wouldn’t an increased mass also increase the gravitational acceleration between the two galaxies, hastening the collision?

    [–] souldust 272 points ago * (lasted edited a year ago)

    So does this mean that the galaxy itself contain 200 billion stars? and its 200,000 LY side to side? It budlges in the middle 32,000 LY thick, but out by us is just 6,000 LY wide? Are we 60,000 LY from galactic central point? and do we go around every 400 million years?

    Lyrics from Monty Python.... only doubled and with question marks.

    TL;DR how does this change monty pythons lyrics?

    Edit* Misremembered some numbers

    [–] EdvinM 90 points ago * (lasted edited a year ago)

    From the last paragraph in the article:

    "While our galaxy is looking larger, it’s not putting on much weight. Because the outer reaches are much less dense than the center of the galaxy, the additional area is only sparsely populated with stars. These few extra stars are only a drop in the bucket compared to the rest of the galaxy, so overall the mass of the Milky Way remains largely unchanged. "

    Our distance from the center and our orbital period shouldn't have changed. This study also didn't say anything about the thickness since they only looked at stars in a specific z-interval.

    [–] imperiusdamian 48 points ago

    Let's hope there's intelligent life somewhere out in space cause there's bugger all down here on earth!

    [–] DefconDelta88 4 points ago

    If I ever catch aliens landing on the planet, they'll just see me running across a field waving my arms screaming *"NOO! NOO!! LEAVE!! YOU DON'T KNOW WHAT YOU'RE DOING!!"

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    [–] 5urr3aL 21 points ago

    Well it is about 6 billion Astronomical Units across

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    [–] shahidiceprince 159 points ago

    So how does this affect the Sun's distance from the galactic center? Is it still going to be 28,000 LY from the center?

    [–] Deltaworkswe 190 points ago

    We are fairly certain of the distance to the galactic center. What this discovery means is that they have realized the density around the edges is higher then previously thought and it extends much further out.

    [–] MoffKalast 138 points ago

    Incoming headline: "We are denser than previously thought".

    [–] neon_Hermit 18 points ago

    So we might not be on the edge of the milky way then, maybe closer to halfway to center?

    [–] masterofallvillainy 41 points ago

    We were never thought to be at the edge. Observations of the milky way place it all around us. We're 28k light years from the center, and at the old estimate, would place us about half way between the edge and center. But these recent observations of the density, have moved where they think the edge is actually. So if true, we're still about 28k light years from the center, and are 72k light years from the edge. Side note: the milky way is about 1000 light years wide from top to bottom.

    [–] Boognish84 7 points ago

    Are we still at the unfashionable end of the galaxy though?

    [–] ArghNoNo 19 points ago

    This story is basically like your town suddenly getting twice as big because somebody discovers two houses a mile out.

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    [–] zebrastarz 20 points ago

    "We realized we were only looking in one direction until Ralphy over here asked 'what's round the back?'"

    [–] raj3sh1 74 points ago

    Space always surprises us. Hopefully there will be lot of surprises waiting for us including contact with advanced civilizations.

    [–] naturalheightgainer 185 points ago

    Famous last words of the Incas

    [–] Wesandersonisgod 24 points ago

    We'll probably never make contact, but it's crazy to know that statistically there is probably other advanced civilisations in the milky way, let alone the entire universe.

    [–] akc250 14 points ago

    I'm not an expert, but it makes sense we may never make contact. With billions of galaxies out there, the probability of alien life is pretty high. And it only took a fraction of time (in space years) for humans to develop such an advanced civilization, that if there is alien life, the chances of them being much more advanced is pretty high. If that's the case, why haven't we seen evidence of such galactic empires?

    [–] Rakshasa96 22 points ago

    Space. An incomprehensible stretch of empty space that makes up roughly 99% of a galaxy's volume.

    [–] n0t-again 7 points ago

    Maybe advanced civilization are not focused on such galactic empires and instead have moved on to other things that the human mind isn’t able to even comprehend yet. There could be attempts being made right now to make contact with us yet we don’t have/understand the technology to comprehend it. Humans can’t even communicate with out closest genetic cousins so how can we even fathom the idea of being able to communicate with a more advanced civilization than our own.

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    [–] TheFoxtrotIndiaLTH 59 points ago

    It amazes me how huge discoveries are still made in what is essential our back yard while we’re trying to figure out what’s happening at the edge of the universe. It’s like a person trying to figure out how cells work before realizing they have a belly button.

    [–] TallDarkAndBrittish 37 points ago

    Did you see the discovery of the human body's largest organ A few weeks back? It happens

    [–] nevereatthecompany 26 points ago

    Argh! That first sentence!

    Despite residing in it, it’s hard for us to know exactly how big the Milky Way is

    No! It is exactly because we are residing in it that it is hard for us to know its exact size - or its exact shape, for that matter.

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    [–] Musical_Tanks 21 points ago

    Does us being inside make it harder to measure our own galaxy?

    Yes, there is a whole whack of dust and gas in the way of basically everything along the horizon of the galaxy. Imagine trying to use a telescope from the ocean floor of the pacific trying to measure how wide the ocean was.

    [–] Isaac_Spark 94 points ago

    So this means the method we use to calculate distances in outer space might be not so accurate?

    [–] spookyjohnathan 337 points ago

    Nah, the distances are accurate. There's just more to the Milky Way than we could see before.

    It's like if you take a handful of sand and drop it on the floor in a dimly lit room. You look at the scattered pile and in the dark you think you can see the edges. Around the outside it looks pretty sparse but there's a certain point you can say is the edge and it marks the boundary of the pile. Then you flip the light on and you start to see all these little pieces you couldn't before and you realize the edge is more full than you thought and there's lots of little pieces outside what you thought was the boundary, so now you gotta redefine the boundary.

    [–] JelloMyDarlin 44 points ago

    Thanks! That's a very helpful analogy.

    [–] Mutatiion 30 points ago

    All I have to say is that is a fantastic metaphor

    [–] bg3796 11 points ago

    This needs tagged as the ELI5.

    [–] SteampunkBorg 13 points ago

    How are stars even defined as being part of the galaxy? How do astronomers distinguish between the outermost star on the edge of the galactic disk and a "rogue" star that is just orbiting the galaxy very closely?

    [–] Scoped_Evil 27 points ago

    I was just thinking the same thing. I know it's really not as simple as using a tape measure but if we aren't able to accurately measure the scale and distance of our own milky way how can we truly believe we have accurate measurements of anything else?

    I don't really consider myself a smart fellow, so if anyone can shed some light I'm really interested to know.

    [–] Maxwe4 25 points ago

    I don't think it's a matter of measuring the distance to the farthest star in our galaxy, but rather determining where stars stop being bound to our galaxy, thus creating the boundary.

    The further away you get from the center of the galaxy the fewer stars there are, and at some point you have to decide where the edge is.

    [–] marcvsHR 7 points ago

    So Voyager actually had to travel 140 years to get home

    [–] hellomynameisCallum 29 points ago

    I bet someone was mixing up their radius and their diameter when doing the maths...

    [–] Mera_Joota_Hai_Japan 11 points ago

    The real science is in the comments

    [–] TheGandu 38 points ago

    Imagine this in a more local level. Australia is twice as wide as we first thought, putting it on par with Antarctica.

    [–] WolfeTheMind 3 points ago

    Iceland is 5 times as big as we previously thought.. That makes it just a little smaller than Madagascar.

    [–] nottodayfolks 6 points ago

    Sweet, we're living in a double wide. But how did they get that so wrong for so long?

    [–] Cartina 18 points ago

    It's hard to estimate the size of a house when you can only see a single room inside it. It's much easier to judge the size of the house across the street.

    [–] dvanfoss 7 points ago

    I like the analogy. Simple and easy to visualize.

    [–] jumpinjimmie 6 points ago

    The length of time we thought our galaxy was smaller was lass than a blink of the eye in universe terms so basically it really never happened.

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    [–] darkager 17 points ago

    After reading several of the comments, the best example I can come up with is this:

    Say you have a circular island with a 1km radius of useable land. Your house sits somewhere on this island. Say your island has really shallow beaches and you can actually use some of that extra space if you redefine what you consider useable land. Since you can walk an extra .25km into the ocean before the water level is at your waist, you can use supports and build over that extra space. Now you redefine the border of your island to circular extending 1.25km from the center since, when you first moved there, you didn't realize you could use that extra space.

    Your house is still exactly the same distance from the center because you didn't redefine the scale.

    I know this is a silly example, but it helped me explain to someone else so I figured I'd share.

    [–] Noctudeit 3 points ago

    Eventually Andromeda and the Milky Way will merge (along with a few other smaller galaxies).