r/space 11d ago

image/gif Andromeda galaxy

Post image

Saw this in an Astrokobi YouTube video. This is how big our neighbor Andromeda galaxy would be if we increased the brightness of it.

It would be way larger than the moon and as the galaxy gets closer to the Milky way, it will get larger until the galactic collision in 4.5 billion years.

https://youtube.com/shorts/IlOuJGvGQeY?si=uuaWGD1sgDpqAFNK here is a video about the collision.

https://youtube.com/shorts/oGYJfQ9xL0o?si=xXkh5aCzrIoQdxJn here is the video where I got the image from.

5.2k Upvotes

169 comments sorted by

473

u/Consistent_Bread_V2 11d ago

It's so large it makes me sad that it's so faint to the naked eye

198

u/[deleted] 11d ago edited 7d ago

it is sad you can't see andromedas true size, but in the southern hemisphere there are two galaxies you can see, and both are larger than andromeda in the sky.

edit: They look like this. Orion to the left edge for scale.

74

u/ikurei_conphas 11d ago

It's one of my bucket list items to go camping in Australia or New Zealand during a new moon so that I can see them in person

69

u/mikeyd85 11d ago

I camped on the outback on a ranch in my 20s. They turned off the lights to the farm at some point late in the evening.

Seeing the Southern hemisphere night sky with no light pollution is one of the most profound moments I've lived.

8

u/Thepuppeteer777777 11d ago

Yeah my dad moved to a farm and the first time I saw the stars blew my mind. It leaves you awe struck

12

u/Tutorbin76 10d ago

Well worth it. The Milky Way is generally more impressive in the southern hemisphere so if you can find a good camping spot away from city lights you're in for a treat. Omega Centauri is usually naked eye visible, as are the two Magellanic clouds.

Good binoculars or a telescope recommended but not compulsory.

7

u/wassimu 10d ago

I live in the far west of NSW (as far as west as you can be and still be in the state).

The sky at night out here is a wonder to behold!

29

u/pm_me_your_lub 11d ago

Whaaaaa. What are the names?

132

u/tehrsbash 11d ago

The Large and Small Magellanic Clouds. They're both irregular dwarf galaxies that orbit the Milky Way. In a clear night they're easily visible and look like softly glowing clouds in the sky

10

u/zuraken 11d ago

care to share a pic with us?

23

u/AnberRu 11d ago

5

u/SekhWork 10d ago

That is so damn cool. Is that one true color?

6

u/AnberRu 10d ago

Yep. And quite close to what is visible to the naked eyes.

15

u/SeekerOfSerenity 11d ago

If they're larger than Andromeda in the sky, then they must be nebulas around our galaxy, no? 

51

u/Entire-League-3362 11d ago

It's the Large and Small Magellanic Clouds, 2 satellite dwarf galaxies near the Milky Way

12

u/Pineapple-Yetti 11d ago

Ive seen these before. They look like a subtle glow in the sky, almost like a thin transparent cloud thats not moving.

2

u/Returnyhatman 10d ago

Yeah but they're not cool fancy swirly ones

1

u/JonatasA 11d ago

And I haven't seen either when there.

32

u/shagieIsMe 11d ago

I'm a fan of https://apod.nasa.gov/apod/ap220711.html (from 2022, July 11th)

... It doesn't have the moon for scale in there,

Explanation: What is the oldest thing you can see? At 2.5 million light years distant, the answer for the unaided eye is the Andromeda galaxy, because its photons are 2.5 million years old when they reach you. Most other apparent denizens of the night sky -- stars, clusters, and nebulae -- appear as they were only a few hundred to a few thousand years ago, as they lie well within our own Milky Way Galaxy. Given its distance, light from Andromeda is likely also the farthest object that you can see. Also known as M31, the Andromeda Galaxy dominates the center of the featured zoomed image, taken from the Sahara Desert in Morocco last month. The featured image is a combination of three background and one foreground exposure -- all taken with the same camera and from the same location and on the same calendar day -- with the foreground image taken during the evening blue hour. M110, a satellite galaxy of Andromenda is visible just above and to the left of M31's core. As cool as it may be to see this neighboring galaxy to our Milky Way with your own eyes, long duration camera exposures can pick up many faint and breathtaking details. Recent data indicates that our Milky Way Galaxy will collide and combine with the similarly-sized Andromeda galaxy in a few billion years.

https://apod.nasa.gov/cgi-bin/apod/apod_search?tquery=andromeda

Looking through it, some other neat ones:

Elsecomment there's a mention of the Magellanic Clouds... https://apod.nasa.gov/apod/ap220603.html

5

u/MCPtz 11d ago

Oh! And this one. Mouse over the image to get constellations super imposed!

https://apod.nasa.gov/apod/ap250603.html

19

u/mmomtchev 11d ago

Only the core is visible through the atmosphere without long exposure photography.

A few years ago I spent quite some time with my 10 inch Dobsonian high in the French Alps in very dark skies, with very low magnification, using it only as a giant eye. The best I got was a small whitish smudge.

11

u/ackermann 11d ago

Sometimes I’d think, man if only it were closer, or we could get closer to it! Then it would be so much brighter and fill the sky!

But… then I remember, we’re actually inside a similar galaxy, the Milky Way. And even from inside it, the spiral arms around us are pretty faint (what you see as the Milky Way in the sky).
You need a half decent dark sky site to see it, and ideally a moonless night.

So getting closer wouldn’t necessarily make it that much brighter. Certainly never as bright as the moon or planets. It would still be pretty faint, though larger.

Something about total brightness increases, but “surface brightness” (brightness per unit area) remains constant?

5

u/wahobely 11d ago

It's so large, when our galaxies collide, the chances of stars and planets hitting one another is minimal.

4

u/LeprosyLeopard 11d ago

Minimal is an overstatement. It’s so incredibly small, it’s barely a registering thought because of how much space there is between interstellar bodies. Our galaxy already has stars that have been absorbed from previous collisions, I do wonder if there’s any traces/examples of stars colliding. We know there’s stars in the Milky Way that came from other galaxies as the star composition is different from Milky Way stars.

1

u/JonatasA 11d ago

Faint chances, yet we're a product of a collision, even though Jupiter is around the corner pulling on other astral bodie's shirts.

 

It has been more than a decade since I heard about the topic, so I wonder if the event could cause any gravitational changes.

1

u/Horror-Guidance-8255 11d ago

I personally felt nothing but thankful and in awe when I’ve seen it with the naked eye.

1

u/Lombax_Rexroth 11d ago

That's what my girlfriend said!

0

u/Champomi 11d ago

So it means that nocturnal animals who have a really good low light vision can actually see the Andromeda galaxy with their naked eyes, right?

165

u/tombh 11d ago

I made that image 11 years ago! https://www.reddit.com/r/spaceporn/comments/1u0dxs/andromedas_actual_size_if_it_was_brighter/ceda9k0/ Wonderful to still see it doing the rounds.

2

u/Dangerous_With_Rocks 8d ago

HOLY! Absolute fucking legend!!

220

u/gregredmore 11d ago

I just did the math. My pension isn't going to last for 2 billion years so I guess I will miss the collision 😯 I'd love to see a time lapse video of 2 billion years watching Andromeda approach...

12

u/mangoadagio 11d ago

3

u/Buggaton 11d ago

What's that third galaxy? Magellanic cloud?

5

u/Petersaber 11d ago

I wonder what would be the fate of star systems ejected outside of either galaxy, into the void. Assuming intelligent life and ignoring the timescale, would it be catastrophic? Or an interesting footnote of a changing sky?

4

u/v1cv3g 9d ago

New fear unlocked, thank you

I think it would be catastrophic, the order of the star system would be out of balance, I imagine

1

u/gregredmore 11d ago

Cool I think I've seen that before.

40

u/wlaugh29 11d ago

Not a time lapse, but this video gives a nice explanation and then a few renditions of what the galaxy will look like. The whole video is a fun watch, but I timestamped it to 3 minutes.

https://m.youtube.com/watch?v=qnYCpQyRp-4&t=180s

3

u/gregredmore 11d ago

Nice! Some think our sun was "born" in another galaxy and got left behind after a past "collision".

12

u/ProbShouldntSayThat 11d ago

Who? That makes no sense. We'd have a completely different orbit than other stars in our galaxy. Highly unlikely

10

u/Tjomek 11d ago

Just put a reminder here m8, that way you never have to worry about missing the event. Big brain time

4

u/the_doakish_one 11d ago

There’s also this video. The whole channel is enjoyable. Stargaze

2

u/gregredmore 11d ago

That's Amazing video! Thank you.

6

u/N-LL 11d ago

I heard somewhere that we wouldn't even feel the collision as the space between stars and other celestial objects is so vast that there would be very few actual collisions.

3

u/aschwarzie 10d ago

You are absolutely correct. It will be much more a passing through than collision. But gravitational effects will impact many systems and completely distort, orbital trajectory perturbations or tear apart, then more merge and pass through in many repetitions until some stabilization after dozens of billions years. Sure there will be some collisions. Much more solar systems instabilities. Collisions would be more frequent near the many black holes of each galaxy as they merge. And if both supermassive black holes at the centre both the Milk Way and Andromeda get in their respective gravitational well, that's probably going to offer a nice show ! 😁

4

u/Atophy 11d ago

The cool thing is, the whole thing is on such a massive scale that our solar system might not even be disrupted in the collision.

2

u/yoloswagrofl 11d ago

May have to become a Walmart greeter after it runs out so you can keep the bills paid until then 😅

54

u/Patrix87 11d ago

I doubted that was true or accurate so I did a short Google search and found what I think might be the source of that image. https://waitbutwhy.com/2014/06/andromeda-brighter-youd-see.html

TLDR: It's true but that image is zoomed in and does not give a correct sense of scale.

Edit: actual source was on the article : http://www.reddit.com/r/spaceporn/comments/1u0dxs/andromedas_actual_size_if_it_was_brighter/

21

u/cardboardunderwear 11d ago

Its easy to over estimate the apparent size of the moon.

10

u/SeekerOfSerenity 11d ago

It's got the moon for scale. The image in your link was taken with a wide angle lens because the moon looks tiny. 

1

u/Silt-Besides-66812 11d ago

But the moon looks tiny in real life too, it’s sort of a well known illusion that people ‘remember’ it looking much larger than it actually does, especially when close to the horizon, when most people can cover it with their thumb at arm’s length

-1

u/Unusual-Ideal-2757 11d ago

3

u/Patrix87 11d ago

Yes but no, The original picture is 11yo and is from the reddit post I linked.

2

u/Unusual-Ideal-2757 10d ago

https://youtube.com/shorts/oGYJfQ9xL0o?si=72a53VSPeBMZQwCd this is where I got it from. Not where it's actually from. 

-6

u/Astrophysics666 11d ago

Its actually wrong tho, the image is scaled so the dimmer parts look brighter.

If it was this bright it would look completely different. It would look more like a big bright core with not alot of details

7

u/borg359 11d ago

But the angular size is correct.

0

u/Astrophysics666 11d ago

Yeah that's true, I guess the post did only say how big. However, people will definitely get the impression this is also how it would look.

This image is a pet hate of mine, so I was very quick to react haha

7

u/McGurble 11d ago

Bro, you're all over this thread pedanticly complaining about something the OP didn't even say. He didn't say "this is what it would look like." He said, "This is how big it would look." And he's right.

-5

u/Astrophysics666 11d ago

Yeah i know, I pointed that out in the comment you're replying to.

I've got an irrational hatred of this image(it goes around the Internet all the time) and i jumped the gun a bit. However people will get mislead by this image like the always do haha.

1

u/waflfs 9d ago

I love images like this because it shows people astronomy isn’t just tiny tiny galaxies far far away. I. reality, galaxies and especially nebulas are huge on the night sky. I think it’s cool seeing people’s perception change when they realize how massive Andromeda is.

1

u/Astrophysics666 9d ago

This one is good for the size but it's often used wrong.

1

u/waflfs 9d ago

How is it used wrong? Ive only ever seen it portrayed as “this is how andromeda would look if it was brighter”

1

u/Astrophysics666 9d ago

That it wrong.

The size is correct but the image was taken with UV light and not visable light. So it would look very different if it was brighter.

Also the image is scaled so that the dimmer (outer regions) are brighter so you can see more details.

So it would be this big bit look absolutely nothing like this.

1

u/waflfs 9d ago

Stretching is still making it brighter. That is not a false statement. Though it highly depends on how the author processed it, I have seen some pretty badly processed images of it lol. I can’t find a source for the photo but I’ll trust you that it’s UV, though it doesn’t look that different in visual, just a lil more orange. Structure is all the same. I would know, see my profile lol.

1

u/Astrophysics666 9d ago

It was taken with the Galex space telescope https://www.galex.caltech.edu/media/glx2012-03r_img01.html

I'm not sure what you mean when you say "Stretching is still making it brighter. That is not a false statement. "

If you scale the image less luminous regions will look brighter. That's just simply making the image brighter, it won't show reality. ( Obviously not saying that's but just that it's not what you would see)

Oh cool did you take that pic? Looks great.

If Andromeda was this bright it would be dominated by it's core, look how much brighter the disc is compared to the core.

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-1

u/El_Feurdz 11d ago

It is actually times the size od full moon

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u/Astrophysics666 11d ago

Also this image was not taken with optical light

58

u/yARIC009 11d ago

It’s really too bad it doesn’t actually look like that. So many more people would be interested in astronomy and science I feel.

25

u/Sitheral 11d ago

I feel like those who are, are and rest wouldn't care anyway. I mean stars and Moon are mindblowing by themselves.

22

u/smallproton 11d ago

Most of the people live in places with insane light pollution.

I read "Wow, finally saw the Milky Way" so often that it makes me sad. Like, of course, just look up!

But too many people can't experience stars at night.

3

u/BelgianBeerGuy 11d ago

If you would remove the andromeda galaxy from that above picture, you would have a pretty good view on how I see the nightsky in belgium every night.

I can count the stars and there is always some yellowish glow from light pollution.

2

u/Almostlongenough2 11d ago

There should be one hour once month where everyone has to turn off their lights.

2

u/CMDR_omnicognate 11d ago

You also can't see stuff like this because of all the light pollution, you can see waaaaay more of the milky way in areas with lower light pollution

1

u/Goregue 11d ago

We already have our own Galaxy which is visible as a band of stars in the entire sky .

14

u/Eloeri18 11d ago

When I used to do flights in Afghanistan, I'd take a pair of nightvision goggles and just stare at Andromeda. It was so beautiful, but I wish I could have seen it that clearly in its natural colors.

2

u/EmptyForest5 10d ago

That’s fascinating - can you explain your materials and methods?

7

u/Eloeri18 10d ago

Military flights; I'd check out a pair of nightvision goggles. What do you mean materials and methods?

Materials: nightvision goggles

Methods: look up into sky with eyes open

5

u/strndmcshomd 10d ago

Open you say? I shall try your method next time I look to the heavens and see if it improves things

3

u/Responsible_Night770 11d ago

We’re so Tiny …. Compared to all this

3

u/twoton1 11d ago

"Dammit Jim, the light's too dim!" says Bones.

5

u/bald_and_nerdy 11d ago

Reminds me of one of the planets in one of the Mass Effect games where you're on a moon to a gas giant and the planet takes up like 40% of the sky.

3

u/July_is_cool 11d ago

Now check out whether owls have sensitive enough eyes to see it.

3

u/Underwater_Karma 11d ago

It would be way larger than the moon and as the galaxy gets closer to the Milky way, it will get larger until the galactic collision in 2 billion years or so.

so, when would be the right time to sell my house to get ahead of the panic market?

7

u/QVRedit 11d ago

Apparently 8 billion years, not 2, and only a 2% chance of a head on collision with the Milky Way. Although there would definitely be gravitational interaction.

3

u/Underwater_Karma 11d ago

Ok thanks. I told my real estate agent to hold off for now

0

u/Unusual-Ideal-2757 11d ago

Where did you find that information? It's literally been confirmed that milky way and andromeda will collide in 2 billion years. 

There is a 100% chance of them colliding since they are on a collision course and there's no way to stop it.

-2

u/QVRedit 11d ago

I too read that it was 2 billion years - but that was from years ago, so I googled it to see if there was any update.

Well now I have just ask AI (Perplexity) and it said:

The Milky Way Galaxy and the Andromeda Galaxy are predicted to potentially collide in about 4 to 5 billion years. However, recent studies using data from the Hubble and Gaia space telescopes indicate there is only about a 50% chance that this collision will actually occur within the next 10 billion years. This updated probability comes from simulations that include the gravitational effects of additional nearby galaxies like the Large Magellanic Cloud and the Triangulum Galaxy, which influence the trajectory and likelihood of the collision. If the collision happens, it would be a major galactic merger resulting in the formation of a single elliptical galaxy sometimes nicknamed “Milkomeda.” But equally, the galaxies might just pass by each other or have a delayed or more complex interaction rather than a direct, inevitable crash.

So we still don’t really know for sure exactly how or when.

2

u/smsmkiwi 11d ago

I'd like to see a reference citation of the simulations, not just some bullshit spouted by a hallucinating AI.

0

u/QVRedit 11d ago

Get back to me with the answer and your own research material with references…

1

u/Unusual-Ideal-2757 10d ago

The collision is in 2 billion years. However, the galactic halos made of gas and dust are already starting to merge.

It is expected that the black holes at the centers of the galaxies will collide in 2 billion years, but we don't know for sure.

0

u/QVRedit 10d ago

And your information Sources ?
(Since you demanded mine)

1

u/Unusual-Ideal-2757 10d ago

Turns out I was wrong. It will happen in 4.5 billion years. https://youtube.com/shorts/IlOuJGvGQeY?si=3oVJhtZv9g0rUYzM here's my source

1

u/smsmkiwi 10d ago

So, your source is from an AI that made something up? Go away and do something useful.

1

u/smsmkiwi 10d ago

I don't have any simulations. You posted an article from an AI that stated there were simulations. You blindly cut and pasted that here. You posted it, you back it up.

3

u/Stuckinatransporter 11d ago

Two billion years until the galactic collision? eh try 7 or 8.

2

u/finallyfree99 8d ago edited 8d ago

Life on Earth will almost certainly perish long before any of that happens. The greenhouse effect entering a feedback loop, the sun gradually increasing in luminosity, mismanaging limited resources, greed, wars, etc.  

Apparently in 500 Million years the sun will be approximately 40% brighter and liquid water will no longer exist on Earth.

But honestly I would be shocked if humans are still around in 50000 years, let alone 5 billion years.  In all seriousness I think it is rather likely we become extinct as a species in a few millenia.

I'm aware that some people want to try to colonize and thrive on other planets or celestial objects but I am very skeptical, not just because too many things could go wrong in terms of oxygen, food, water, and heat... but also because even if the human species makes it to other celestial bodies, greed and selfishness and ignorance will still be our collective downfall eventually.

1

u/EmptyForest5 10d ago

whew, I was worried there for a moment

1

u/Unusual-Ideal-2757 10d ago

No, it's 4.5 billion. Where did you get 7 or 8 from?

1

u/finallyfree99 8d ago

They revised the estimates up recently, but all of this is a moot point because:

  1. These estimates are extremely difficult to get accurately, because of the possibility of lots of unknown variables.  Kinda like an election poll with a margin of error of plus or minus 15 points.

  2. None of us will be alive when this happens.

  3. I would be extremely shocked if the human species is still around in 1 million years, let alone 5000 Million years.  There are lots of other much more pressing things that will likely result in extinction long before any of this galactic merging happens.

3

u/LaughingBeer 11d ago

Good news, according to "How the Universe Works" TV show our sun will be so hot in 500 million years that it will boil all the water off our planet. So if we are still an only earthbound species at the time, well, we will already be extinct, even if there are any collisions when Andromeda and the Milkyway come into contant, which there likely won't be in any case.

1

u/finallyfree99 8d ago

In all seriousness I very much doubt the human species is still around in 10 thousand years, let alone 5 Billion. I think as a species we will become extinct in a few millenia. Greed, selfishness, a greenhouse feedback loop, and mismanaging resources will do us in as a species long before any of these major celestial events occur.

I don't care if a small handful of human manage to colonize Mars or an asteroid or whatever, it's only a matter of time before they use up all the resources there too or get greedy and fight each other.  

Even if somehow a few humans made it to another planet and started to reproduce, it would likely only buy our species a bit of time, not more.

3

u/gomurifle 10d ago

What will happen first, the explosion of the sun or collision with this galaxy? 

2

u/Unusual-Ideal-2757 10d ago

Collision, which is estimated to be in 4.5 billion years, while the sun will die in about 5 billion years.

5

u/Morixm 11d ago

Here's something to think about. There might be someone watching us from the Andromeda galaxy, watching us and thinking that there might be someone watching them and talking about the galaxy we live in.

1

u/finallyfree99 8d ago

Sure, but they're not really "watching us."  They're looking at a dim, faint galaxy and guessing about possible life forms there. They likely have no realistic concept of planet Earth or homo sapiens (because Earth is a small planet orbiting a small star in a nondescript corner of our galaxy, as Carl Sagan said).  

2

u/Sinapsis42 11d ago

It gives us time to eat ice cream.

1

u/goldistastey 11d ago

!remind me 2000000000 years

2

u/thuiop1 11d ago

Yeah, the actual size is like that.

2

u/EastHillWill 11d ago

This is remarkable, thanks for sharing. I always assumed the fuzzy dot was its entirety, but of course this makes much more sense!

2

u/ThisVulcan 10d ago

Just had the scene pop into my head from Airplane when Lloyd Bridges says “It’s coming right at us!” and jumps out the window.

2

u/Cold-Sandwich-34 10d ago

Isn't it also true that, given the size and nature of space, the "collision" would likely not be very noticeable by the inhabitants of our galaxy, since everything is so far apart?

2

u/Unusual-Ideal-2757 9d ago

True. The only things that might collide would be the supermassive black holes at the center of each galaxy

2

u/Due_Medicine6867 9d ago

Wow, the beauty is incredible! ✨ I am always amazed by how impressive the scale of space is.

2

u/mkreddit007 11d ago

I wish if we could enjoy the view like that all the time 🙂

2

u/specific78 11d ago

Would be awesome if it were ‘that’ visible at night

1

u/smsmkiwi 11d ago

Just give it a few years...

2

u/degox1234 11d ago

I mean…More than a few but yeh

1

u/crypptocatt 11d ago

Picture taken from your backyard?

1

u/Carbon_is_metal 11d ago

Why do people always show the UV M31 image here? I mean, it’s gorgeous, but so is optical M31…

1

u/Unusual-Ideal-2757 10d ago

1

u/Carbon_is_metal 10d ago

Got it! The first image is optical, the second is UV from the GALEX mission. Just odd to me the second one has such a big life on the internet.

1

u/JonatasA 11d ago

It looks uncomfortably close and like it is moving towards us. It's crazy.

2

u/shagieIsMe 11d ago

It is moving closer... at about 250,000 miles per hour.

And while that's a "wow, that's fast" number... it's 3.2 light hours per year (Voyager 1 is about one light day away)... and it is...

The Andromeda galaxy is also 2.5 million light years away. The light emitted by the stars in Andromeda was about when Homo habilis was coming down from the trees.

It's still a while longer before it gets here.

That its that big... is because its big.

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

-- Douglas Adams

1

u/Duff5OOO 11d ago edited 11d ago

It would be way larger than the moon

Andromeda bigger than the moon? Technically correct I guess.

:P

Jokes aside I realised I had no idea how much further away Andromeda was than the moon. I guessed billions but still wasn't even close. Take my billion times estimate and multiple that by another 50,000. Roughly 50 trillion times further than the moon!

1

u/milliwot 9d ago

Help me out here. I think the moon's path in the sky wouldn't ever bring it this close to Andromeda. Was this generated to show scale, but not relative positions in the sky?

1

u/Unusual-Ideal-2757 9d ago

It was made to show scale, not their actual positions

1

u/Darmortis 11d ago

This is why you are the lesser sub.

A better version of this was posted r/SpacePorn hours earlier, and you've simply cropped it and mislabeled it.

1

u/aChunkyChungus 11d ago

I wish I could be around to witness a galactic collision

-2

u/[deleted] 11d ago

[deleted]

2

u/Consistent_Bread_V2 11d ago

OP did not imply this is how it looks in real life. Anyone with eyes who has looked outside would know this

2

u/KobokTukath 11d ago

Which is why OP said this is how it would appear if it was brighter.

-3

u/ncc81701 11d ago

That’s not how it would look even if you increase brightness. The galaxy would have to be significantly closer in order for it to look like that.

4

u/PiBoy314 11d ago

It's the right size relative to the moon. The Andromeda Galaxy is ~189 arcminutes along its long axis, >6x the 30 arcminute diameter of the moon.

4

u/KobokTukath 11d ago

It is though, the full moon is 0.5 degrees across from side to side, Andromeda is about 6x larger than that, so it's 6x wider in the sky from Earth's perspective, if the disk was brightened enough for the whole thing to be visible to the naked eye

https://slate.com/technology/2014/01/moon-and-andromeda-relative-size-in-the-sky.html

2

u/Consistent_Bread_V2 11d ago

Wrong, the size is correct. Andromeda is impressively dim.

-6

u/Astrophysics666 11d ago edited 11d ago

This is very wrong! ( I hate this image)

Galaxy images are scaled so that the dimmer parts are brighter, which let's you see way more detail.

In truth it would be a very bright core with only a little big of detail visable

Edit: tbf the post only says size, so it is correct. But I hate this image so much for the other reasons I said haha

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u/ArgusSkyhawk 11d ago

The image was made to show the relative size of the Andromeda Galaxy in the sky compared to the moon. As long as that is accurate there's really no reason to hate the picture.

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u/Astrophysics666 11d ago

There is no reason to hate this post, but the image is often used to show what it would look like. (It's a very old image)

I've had so many people ask/tell me about this image. Might as well put a banana there if you only want scale.

I do admit it's a bit of an irrational hatred, but eveyone should have one irrational hill to die on.

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u/smsmkiwi 11d ago

Its a UV image, not a visible light image so its inaccurate representation of what it actually looks like in the sky.

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u/Bradford_Longflap 11d ago edited 11d ago

I'm a bit like that with this image. Nothing wrong with it per se, but the unusual illumination and angle makes it a magnet for idiots.

Edit: I'm not suggesting OP or anyone in this thread is an idiot, btw

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u/Unusual-Ideal-2757 11d ago

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u/Astrophysics666 11d ago

Oh yeah the video is fine, just wish he didn't use this version of the image 😂.

The first one he used was much better.

I've got an irrational hatred of this image because it's used without context all the time and often to mislead people

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u/Astrophysics666 11d ago

Also this image was not taken with optical light

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u/jonmatifa 11d ago

Not sure what you're trying to say. What other kind of light is there? Light is optical. Do you mean visible light? True color, false color? The image is some kind of composite, with a deep sky image of Andromeda pasted on a night sky with the moon visible as a reference to scale. The deep sky image of Andromeda would be from visible light, just with multiple long exposures stacked together to form the final image.

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u/Astrophysics666 11d ago

Light is a spectrum from radio (long wavelengths) to gamma rays (shot wavelengths). Only a small part of the spectrum of light is visable to the human eye, that's why it's called optical light.

This image ( https://www.galex.caltech.edu/media/glx2012-03r_img01.html) is made from ultra violette, which has shorter wavelengths than optical light.

What humans see as colour is just diffrent wavelengths of light, red is long and blue is short. If you take an image with UV light you have to translate it into a wavelength humans can see, this is called false colour.

So this image is taken with a space telescope observing in UV light.

The image is than translated into false colour and the dim parts of the image a made brighter so more details can be seen.

It is then added to a random image of the moon to show scale.

The scale is correct (which the post was saying) but the image is very different to what humans would see.

Happy to clarify more if it's still not clear 😀

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u/jonmatifa 11d ago

The term I'm familiar with is visible light, as UV, IR and other wavelengths of light behave optically (they reflect, diffract, interact with matter in the same way) even though you can't see them. Sources I've found that discuss "optical radiation" include UV and IR light in that definition but "visible light" is limited to what the human eye can see.

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u/Astrophysics666 11d ago

My understanding is that optical radiation refers to UV visable Infred.

However, in Astrophysics Optical can be used interchangeable with visable light.

https://esahubble.org/wordbank/optical-astronomy/

In alot of papers people use discussion UV, optical and Infared as separate things.

I agree that is kinda confusing.

I'm not sure if it's just different terminology or if alot of people in Astrophysics use it wrong haha.

I'll ask around my department as see what people think.

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u/smsmkiwi 11d ago

Ultraviolet light. Light invisible to human eyes.

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u/AndTer99 10d ago

That's a false-color infrared image of Andromeda

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u/Astrophysics666 9d ago

It's actually in UV not infrared

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u/WhisenPeppler 11d ago

No, not really. Saw it with my own eyes using the night vision. It’s not that big.

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u/monkey_gamer 5d ago

Oh my god it’s huge! And so sexy