[HN Gopher] First pictures from Euclid satellite reveal billions...
___________________________________________________________________
First pictures from Euclid satellite reveal billions of orphan
stars
Author : geox
Score : 239 points
Date : 2024-05-23 13:22 UTC (1 days ago)
(HTM) web link (www.nottingham.ac.uk)
(TXT) w3m dump (www.nottingham.ac.uk)
| fellerts wrote:
| TFA specifies "more than 1,500 billion". That's more than a
| _trillion_, not "billions"! Why the reluctance to use the proper
| number?
| Rebelgecko wrote:
| The UK used a different definition of trillion until ~50 years
| ago (10^18 vs 10^12), so it probably helps avoid ambiguity
| sammyoos wrote:
| The designation of trillion is ambiguous:
| https://en.wikipedia.org/wiki/Trillion
| philomath_mn wrote:
| Same for one billion: https://en.wikipedia.org/wiki/Billion
|
| I've never heard someone use the long scale, it is only ever
| mentioned as a novelty. I think the scientific community, at
| the very least, has standardized on the short scale.
| pxndxx wrote:
| The long scale is common in French, German and Spanish for
| example. English usually uses the short scale. The
| scientific community uses SI prefixes, which aren't part of
| either scale (you don't say a billion joules which is
| ambiguous, you either say a terajoule for a long-scale
| billion or a gigajoule for a short-scale one).
| piva00 wrote:
| Also common in Swedish, miljon = 10^6, miljard = 10^9,
| biljon = 10^12, biljard = 10^15, triljon = 10^18.
| philomath_mn wrote:
| Fair enough, but I still would be surprised to see the
| long scale used in scientific communications written in
| English.
|
| Re SI Prefixes: you _could_ make the argument that they
| are essential another short scale since they are named
| every 3 orders of magnitude.
| hifromwork wrote:
| My country uses long scale. I've never seen long scale
| used in English, so I don't think it's ambiguous.
|
| But! When non-native speakers read news, they are not
| always completely fluent in English, or even aware the
| short scale exists. This is true even for journalists.
| I've seen articles written in a serious newspapers where
| a journalist confused "billion" and "trillion", because
| they incorrectly translated English "billion" to my
| language "bilion". Journalists! A cross-cultural mistake
| not unlike foots vs meters.
|
| So that's one thing to consider if one wants to avoid
| miscommunication at all cost. I'm not sure if it is
| important enough to take into account - after all people
| _should_ know better.
| whimsicalism wrote:
| what? the scientific community absolutely also uses
| billion and trillion by short scale
|
| it's all over papers and nobody is ever using the long
| scale that i've seen
| ivan_gammel wrote:
| Are those papers in English? Long scale may be translated
| to short scale if the paper is translated from the
| original language where long scale is common.
| whimsicalism wrote:
| yes, i'm talking about the scientific community - papers
| are almost exclusively published in english or with an
| english version. long scale translated to short scale
| would be a mistranslation, imo
| rob74 wrote:
| The long scale is far from just a novelty, most European
| countries other than the UK use it. Actually I thought it
| was used in all non-English-speaking countries, but
| Wikipedia showed me that the situation is far more
| complicated than I thought:
|
| https://en.wikipedia.org/wiki/Long_and_short_scales#/media/
| F...
|
| Besides short scale and long scale, there is a sizable
| "short scale with milliard instead of billion" fraction,
| and of course some countries (China, India, Japan, Greece)
| have completely different systems. Most interesting is that
| Portugal uses the long scale, while Brazil uses the short
| scale. That must be confusing...
| whimsicalism wrote:
| almost all scientific writing i can find from people in
| portugal uses the short scale. english formal
| communication has standardized around the short scale
| alenrozac wrote:
| All scientific writing in Slovenia uses long scale. I've
| heard it being used in EU institutions too.
| whimsicalism wrote:
| > All scientific writing in Slovenia uses long scale.
| I've heard it being used in EU institutions too.
|
| I am able to easily find plenty of Slovenian academics
| using short scale in their scientific writing. Remember,
| English is standard for scientific writing and publishing
| in international journals. I have yet to find a single
| one using the long-scale, actually.
|
| https://link.aps.org/accepted/10.1103/PhysRevD.97.123540
| https://iopscience.iop.org/article/10.3847/1538-3881/abe6
| a7/... https://link.springer.com/content/pdf/10.1186/s402
| 94-016-001...
|
| > observations by cataloging positions and redshifts of
| billions of galaxies in the next decade > and the
| configuration is stable over billions of years. >
| (networks having up to a billion of vertices; there is no
| limit--except the memory size--on the number of lines
| phkahler wrote:
| >> Same for one billion:
|
| So that's how the US government will make the mult-trillion
| dollar debt go away. They'll just call it Billions.
| tzot wrote:
| OTOH the phrase "a thousand million" for 109 is not that
| uncommon. From what I've seen, in places where
| billions/trillions are mentioned and it's important that
| the number is accurately specified, a representation with
| digits or the exponent of 10 are typically provided.
| FabHK wrote:
| Agreed that the short scale has become more prevalent,
| lamentably. I find 6n more pleasing than 3n+3.
| whimsicalism wrote:
| my understanding is the long scale has largely died out
|
| think it is more than permissible to use what is
| scientifically standard (trillion = 10^12)
| tzot wrote:
| "Scientifically standard" are the SI prefixes. So, given
| the ambiguity of what 1 gigastar is (1/1000th of 1 terastar
| or a really huge star?) one should say "1012s of stars"
| maybe.
| whimsicalism wrote:
| Yes, the SI prefixes are one example of something that is
| scientifically standard. The short scale is another.
| Tor3 wrote:
| Died out in _English_. Not in other languages where long
| scale was and is used, that hasn 't changed at all. I'm not
| aware of any other language shifting from long scale to
| short scale (for languages traditionally using long scale).
| whimsicalism wrote:
| think it is also dying out among many other languages
| like portuguese
| jl6 wrote:
| Billions is not wrong. Trillion _s_ (plural) would be wrong.
| "More than a trillion" would be needless words.
| dylan604 wrote:
| A very famous person is very well known for his particular
| style of enunciating billions. After that, saying any other
| word is just a wasted chance of having Sagan's voice in their
| head reading the word.
| BurningFrog wrote:
| A lot of people outside of HN don't know what a trillion is.
| wrycoder wrote:
| Tell them it's comparable to $1 bills laid end to end from
| here to the sun.
|
| And tell them it's only 1/35 of the US national debt, which
| is roughly $350,000 per US taxpayer.
| s1artibartfast wrote:
| Easy fix, just use $100 bills and we are only 35% of the
| way to sun. Problem solved.
| dwaltrip wrote:
| How many Olympic swimming pools is that?
| withinboredom wrote:
| It's several football fields full of cash.
| bregma wrote:
| American football or the more globally popular kind?
| withinboredom wrote:
| Which do you think? :p
| rurban wrote:
| The proper unit would be Parsec, imho
| seanhunter wrote:
| Parsec is a unit of distance[1]. They were counting a number
| of stars.
|
| [1] Defined as the distance at which 1AU subtends an angle of
| one arc second or 648000/pi AU
| https://en.wikipedia.org/wiki/Parsec
| fnordpiglet wrote:
| I assume this is being hugged to death?
|
| 504 Gateway Time-out
|
| The server didn't respond in time.
| CapitalistCartr wrote:
| HN often Slashdots stuff.
| pictureofabear wrote:
| Now that's a name I haven't heard in a long time.
|
| https://i.imgflip.com/kj336.jpg
| floxy wrote:
| Website seems down. Alternate links:
|
| https://scitechdaily.com/euclid-mission-uncovers-1-5-trillio...
|
| https://thedebrief.org/euclid-first-look-stunning-new-images...
|
| ...I was under the impression that there was a faint blue glow
| coming from everywhere, that was hypothesized to be extra
| galactic stars. Has there been any follow up on that?
|
| https://en.wikipedia.org/wiki/Intergalactic_star#Observation...
| cuSetanta wrote:
| Always a bit special to see science come from a spacecraft I had
| the pleasure of working on. Honestly there were a lot of issues
| during the build of Euclid that I was very glad to not be a part
| of, but seeing the images coming out of it now is pretty damn
| impressive.
|
| Hope all of the engineers that struggled to get this mission
| spacebourne can enjoy!
| seanhunter wrote:
| Congratulations. That's an amazing project to be a part of, and
| it looks like some really jawdropping science is going to
| result.
| cuSetanta wrote:
| Quite a small part, but yeah, the science missions are always
| special to be a part of, even if its small.
| ck_one wrote:
| Can you share some insights on what the issues were?
| cuSetanta wrote:
| I wouldn't want to go into specifics, as it's easy to look
| like I was slinging mud.
|
| But if you have seen the issues that Starliner has had
| recently, I would echo the statement from there, that valves
| are hard. Very hard. Everything to do with pressurised
| systems in space is hard. But the propulsion team worked it
| through and are now seeing the fruits of the long hours.
| bbor wrote:
| Thanks for sharing a human moment, honestly inspiring to
| contemplate. I have a few interview questions if you find the
| interest:
|
| 1. What was testing/safety/static checking culture like? I have
| experience within a NASA software contractor that spent a lot
| of time and stress on balancing classic "aerospace-y"
| engineering practices with the more modern ones out of SV,
| which are paradoxically both more and less rigorous than the
| old ways across different situations. In other words: in a
| project like this where "groundbreaking" is expected, how
| closely did you stick to tradition?
|
| 2. I'm dumb and just realized: did they pick Euclid because
| it's in the EU??
|
| E: 3. What's it like to be "accomplished"? Like, more so than
| any random app ceo or sales consultant or whatever, you have
| now accomplished what would be many young people's dream: to
| help build a spacecraft that's advancing science significantly.
| I'm assuming all stress dissolves and any sacrifices resolve
| into being definitely worth it? Asking for a friend, of course.
| cuSetanta wrote:
| Love to answer questions if I can.
|
| 1. The testing culture is very thorough. I was involved on
| the propulsion side of things, and as such the safety is
| taken very seriously, for the safety of the test/production
| engineers and of course the spacecraft. Propulsion systems
| are typically integrated in such a way that it is very
| difficult (nigh impossible at times) to separate them if an
| issue is found at a later stage, so the testing goes through
| things with a very fine comb. And even still things can go
| wrong and can sometimes only be found at a later stage.
|
| From the spacecraft Assembly Integration and Test (AIT) side
| of things, which is where I work, things are traditional but
| pragmatic. If a new way can be shown to be more reliable we
| will adopt it. But not before it is very well understood and
| characterised. In space, heritage is king, the best way to
| know if something will work in space is to already know it
| works in space. So it can take a lot of evidence for a new
| method/system to be adopted, and when we think we are moving
| quickly, it probably looks like a glacial pace to others.
|
| During the build and test, we are often so far from the end
| goal of a spacecraft, its not possible to see the
| "groundbreaking" aspect of things. Perhaps the payload
| designers and engineers can see this better.
|
| 2. I believe it is named after Euclid, as the father of
| geometry, as the mission goal was to measure the geometry of
| the universe. And also yes, go Europe.
|
| 3. Christ, accomplished? I love the idea of being
| accomplished in many ways, but its also a scary concept.
| Wouldn't want to be having notions of grandeur either. I am
| very lucky to have worked on many great projects, in many
| countries, and in a job that I honestly think I am good at
| and enjoy. But I am always surrounded by so many people who
| have done so much more, so it mostly feels like I am trying
| to catch up really.
|
| The science missions really are special to me, I have a
| background in Astrophysics, and sort of fell into spacecraft
| engineering. So it is always a real pleasure to get to work
| on something I understand on a deeper level. But most of the
| missions I have worked on have not been so special. Most
| spacecraft are to make money or do something for a military.
| Its why I have so much time for ESA. Even with their issues
| (cost, time, etc.), they really feel like they do the
| important missions for humanity. Nasa and Jaxa too, but they
| mix in a higher amount of the less special stuff in my
| experience.
|
| The stress and sacrifice was stressful and sacrificial(?). I
| wouldnt say it was worth it, or not worth it. Its an odd one.
| Mostly I have just tried to do cool shit as often as I can,
| and I have been damn lucky.
|
| Thanks for the kind words though, and I hope I wasn't
| rambling too much in my response.
| DrNosferatu wrote:
| Indeed, thanks! Euclidean here too ;)
| cuSetanta wrote:
| Oh hey! Congrats on the awesome mission!
| PeterCorless wrote:
| We can spot the orphan stars at this distance. However, Euclid
| needs to turn to closer targets than the Pegasus cluster to spot
| rogue planets.
|
| https://www.theguardian.com/science/article/2024/may/23/eucl....
|
| In this case, it found dozens of rogue planets in the Orion
| nebula, which is only 1,500 ly away.
|
| I am presuming there are also going to be great numbers of rogue
| planets in deep space, not tied to any star or galaxy. But there
| would be no way for Euclid to spot them at that distance. Stars
| were hard enough.
|
| I presume, in due time, there will be some sort of calculable
| estimation or projection of orphan stars and rogue planets per
| cubic parsec or kilosparsec.
| floxy wrote:
| >We can spot the orphan stars at this distance.
|
| Can we resolve these individual orphan stars? Or just see the
| cumulative glow from a lot of them?
| PeterCorless wrote:
| Note that there are two different announcements today, and I
| need to clarify my comment above.
|
| * One piece cited viewing 1.5 trillion stars in the _Perseus_
| cluster of galaxies, which is 240 million ly distance:
| https://www.nottingham.ac.uk/news/first-pictures-from-
| euclid...
|
| * The other cited spotted stars in galaxy cluster Abell 2390,
| which is in the Pegasus constellation, which is 2.7 billion
| ly away -- an order of magnitude further away: https://www.es
| a.int/Science_Exploration/Space_Science/Euclid...
|
| If I am reading this correctly, it seems like Euclid was able
| to see the light from individual stars ripped from their
| galaxies in Abell 2390. Which is quite the accomplishment.
|
| Please let me know if I am reading too much into this, or
| reading it incorrectly.
| malfist wrote:
| Abell clusters are really cool to image if you can see some
| of the closer ones. The deer tick galaxies are really neat
| Ringz wrote:
| It would be interesting to calculate how much these stars
| contribute to the mass deficit of the universe.
| Retric wrote:
| Not just stars, it implies there's a lot of planets,
| asteroids, etc tossed out there.
| recursive wrote:
| I suspect in any solar system, the mass of the non-stars
| are a rounding error compared to the whole system's mass.
| Retric wrote:
| I suspect the current contents of a solar system is a
| poor proxy for everything that's been ejected from it.
| Pluto is 0.0006 light-years from the sun, there's a great
| deal of space between stars we don't know that much
| about.
|
| Further we dramatically underestimated the number of expo
| planets for decades. Quite reasonably we don't put a lot
| of weight on stuff we can't detect.
| SJC_Hacker wrote:
| > I suspect in any solar system, the mass of the non-
| stars are a rounding error compared to the whole system's
| mass.
|
| A brown dwarf orbiting a red dwarf would beg to differ.
| recursive wrote:
| Is the brown dwarf not considered a star? I don't know.
| Retric wrote:
| "A brown dwarf is an object which is made of the same
| stuff as stars, but does not have enough mass for
| hydrogen fusion (combining hydrogen atoms into helium
| atoms). Hydrogen fusion is what makes stars glow. Brown
| dwarfs are not massive enough to do this, so they are not
| stars. On the other hand, they are not regular giant
| planets, because they do glow."
|
| https://simple.wikipedia.org/wiki/Brown_dwarf
|
| While very young they generate heat from both deuterium
| fusion but that only lasts millions to tens of millions
| of years. Energy from radioactive decay and their slow
| contraction lasts for much longer.
| deprecative wrote:
| The nebulous space the Brown dwarf occupies in terms of
| classification is fascinating to say the least. I'm a
| passing not even hobbyist on the subject but that they
| glow but not like that is really interesting.
|
| When I think of the brown dwarf I am also reminded of the
| hypothesized black dwarf. This would be the stage after
| white dwarf. It's hypothesized because it takes longer
| for the white dwarf bodies to cool than exists presently
| in the history of the universe. It's only a handful of
| sentences and will largely repeat the previous paragraph
| but there's the wiki page for black dwarf.
|
| https://simple.wikipedia.org/wiki/Black_dwarf
|
| Very interesting stuff all around. Space is so fucking
| cool, y'all.
| raverbashing wrote:
| Which are both "low mass" compared to other stars out
| there
|
| It might even be possible to have this combination weigh
| less than our sun
| malfist wrote:
| The sun accounts for 99.9+% of the solar system mass if I
| recall correctly
| Retric wrote:
| Close it's ~99.85% excluding the ort cloud. However
| there's a major bias towards smaller stars because they
| last longer though conversely they are harder to detect.
| martinpw wrote:
| Probably not that much relatively.
|
| Specifically the Perseus cluster reported on here has a mass
| of around 10^15 solar masses in total. Of that ~10% is in the
| form of stars, 20% is intergalactic gas and the remainder is
| dark matter.
|
| The report here says 1.5 trillion of these stars in this
| cluster which is ~10^12 solar masses (assuming average star
| mass is similar to the sun's.)
|
| So the newly observed stars reported here are around 0.1% of
| the total cluster mass, or around 1% of the total mass of
| stars in the cluster. All very approximate of course.
| leke wrote:
| It's dead, Jim.
| gcanyon wrote:
| The stars near us in the Milky Way are tens of light years away,
| and we'll have to do some incredible science and technology to
| visit them.
|
| How much worse would it be if you were an intelligent life form
| on a planet orbiting one of those orphans, and the nearest star
| was a thousand, ten thousand, even a million light years away?
| outworlder wrote:
| At some point, given the universe's expansion, galaxies will be
| moving away so fast that the observable universe will be just
| one galaxy. Already, the effective rate from galaxies far away
| is actually faster than the speed of light. Even at light
| speeds, we cannot reach 94% of them as we would never catch up
| if we left today. In cosmic scales of many billions of years,
| observers on every galaxy will eventually think that their
| galaxy is the only one that has ever existed.
|
| Large distance and time scales are rather gloomy.
| dumpsterdiver wrote:
| Indeed, the only hint they would have that they were not
| alone would be the "weak" gravitational effects of all other
| existing matter pulling at the fringes of their visible
| universe. Perhaps they'll refer to this phenomenon as "dark
| energy".
| mr_toad wrote:
| The galaxies in our local group are gravitationally bound.
| 0xfae wrote:
| Right, but isn't the expansion increasing? So if they don't
| merge into one big galaxy at some point the expansion would
| out run gravity?
| arbuge wrote:
| > In cosmic scales of many billions of years, observers on
| every galaxy will eventually think that their galaxy is the
| only one that has ever existed.
|
| Unless of course some of them manage to find ways to preserve
| information and keep records over those billions of years.
| The lost galaxies will be known from that.
| saulpw wrote:
| But the information would still be forever locked away in
| its own galactic island. Even transmitting at the speed of
| light, the information could never reach any other galaxy.
| So no, in this far future, a galaxy would only be able to
| know itself.
| arbuge wrote:
| We have records of other galaxies right now. Assuming we
| manage to preserve those and humanity over these kinds of
| time scales, our descendants would be able to access
| those records and learn that other galaxies once existed
| that are beyond their cosmic horizon now.
| pavel_lishin wrote:
| There is a novel written with that premise as the background! I
| can share the title with you, if you'd like - that particular
| premise is a very small part of the novel.
| neamar wrote:
| I'd like to read it!
| akuchling wrote:
| Iain Banks's "Against A Dark Background"?
| pavel_lishin wrote:
| Indeed, though I was hoping to avoid posting an explicit
| spoiler - I'd have rot13'd it or something.
| datavirtue wrote:
| One word. Time warps.
| FredPret wrote:
| Might be much harder to bootstrap your astronomy in that
| situation as well.
|
| As I understand, we built much of our picture of the universe
| on the fact that we can do precise parallax measurements of
| nearby stars.
|
| Then we used that to see how far the nearby Cepheid variable
| stars are, and used the patterns those exhibit to measure
| distant galaxies. Then at some point we could determine the
| distance to a certain kind of supernova, and now we have a 3D
| model of the whole observable universe.
|
| But it starts with parallax measurements which are limited in
| range.
|
| https://www.jpl.nasa.gov/news/cosmology-standard-candle-not-...
| gcanyon wrote:
| Ooh, this is super interesting! This video by The Science
| Asylum lays out the "distance ladder" in great detail:
| https://www.youtube.com/watch?v=zrpdwJNNskk This wikipedia
| article also lays out the distance ladder:
| https://en.wikipedia.org/wiki/Cosmic_distance_ladder so if
| our hypothetical "intelligent species on a planet orbiting an
| orphan star" were more than 30,000 light years away from the
| nearest star, they wouldn't be able to measure that distance
| with accuracy using the technology we have now. That might
| not apply to ranging whole galaxies? And they could get
| better with time? In any case, my idea that they might take
| off for a "nearby" star "only" ~100 light years away because
| they don't know better is foolish.
| belter wrote:
| Impressive photos from the ESA site:
| https://www.esa.int/Science_Exploration/Space_Science/Euclid...
| IncreasePosts wrote:
| My God, it's full of stars.
| belter wrote:
| Just remember...Attempt no landing in Europa.
| Tepix wrote:
| That's a lot of stars indeed. The human mind cannot even
| comprehend this number. Not to mention all those planets and
| moons around those stars
| NKosmatos wrote:
| My favorite reply in similar comments is the reference to the
| total perspective vortex by The Hitchhiker's Guide to the
| Galaxy:
|
| https://hitchhikers.fandom.com/wiki/Total_Perspective_Vortex
| darkwater wrote:
| I really find hard to believe how people can say "well, maybe
| it's not that easy to have other forms of life in the Universe".
| I mean, we have a cluster with thousands of galaxies, which make
| it for millions of stars, 240 _MILLION_ light years away. Which
| means that there is a 240 million years window in which we are
| basically blind. Any communication from there will never reach
| the human race, most probably. Philosophically we can say there
| is no life there as we are concerned, because we will never be
| able to see any proof of it, but that doesn 't mean that there
| was anyway, or there currently is, and maybe in more than one
| planet.
| throwaway765123 wrote:
| "I'll tell you one thing about the universe, though. The
| universe is a pretty big place. It's bigger than anything
| anyone has ever dreamed of before. So if it's just us... seems
| like an awful waste of space. Right?"
|
| -- Contact (1997)
| irrational wrote:
| Waste of space seems like a poor phrase. It seems to imply it
| should be used by intelligent life, and if it isn't, then
| it's a waste.
| GuB-42 wrote:
| If the universe is infinite like we think it is, then there is
| life somewhere, in fact, there is an infinite number of copies
| the earth exactly like or own, with a copy of you and me on it.
| We are just "blinded" by the limits of the observable universe.
|
| So, we are almost 100% sure that there is extraterrestrial life
| somewhere in the universe, but if there is no possible causal
| relationship between us, what's the point? It is also the same
| reason why "the universe" is often shorthand for "the
| observable universe". There is probably something beyond it,
| but we have no way to know what it is, so it might as well not
| exist.
| shkkmo wrote:
| I am not aware of any models of the universe that posit an
| infinite mass.
|
| Edit: Also, "observable universe" is a frequently
| misunderstood concept. Just because something is now outside
| the observable universe (the distance between them and us is
| big enough so that the rate of expansion of the universe
| between us and them is higher than the speed of light)
| doesn't mean that we aren't, today, receiving light from a
| long time ago when the object was closer. If you go far
| enough back in time you can "see" the entire universe . As
| time passes, more and more mass moves outside of the
| observable universe since the size of the sphere is constant
| relative to the rate of expansion.
| kstrauser wrote:
| That would imply there's an edge to be closer to, which
| doesn't align with my understanding of it.
| dragonwriter wrote:
| > If the universe is infinite like we think it is, then there
| is life somewhere, in fact, there is an infinite number of
| copies the earth exactly like or own, with a copy of you and
| me on it.
|
| This requires more assumptions than just infinite scale.
| grantpitt wrote:
| Right, like in math, not all infinite sequences contain
| every finite subsequence. For example, a non-repeating
| sequence of 2's and 7's contains no sequence "4". The
| further condition is that the number be normal[1].
|
| Also, TIL we don't know whether p is normal thus the
| popular claim that "every string of numbers eventually
| occurs in p" is not known to be true
|
| [1] https://en.wikipedia.org/wiki/Normal_number
| drlemonpepper wrote:
| this is such a commonly-repeated fallacy. just because
| something is infinite, doesn't mean everything is possible.
| the sequence 1,3,5,7,9,... is infinite, and yet it contains
| no even numbers. there are many such cases.
| jokellum wrote:
| In this case, the existence of earth is an even number, so
| I don't see how this is a fallacy.
| layer8 wrote:
| Take the sequence of prime numbers, with Earth = 2. ;)
| renegade-otter wrote:
| People underestimate how dead and hostile the space is to life
| in general. First of all, you can just swipe most of the
| available galaxy space off the table because of radiation - the
| center of the Milky Way, close to our "core" black hole, is
| just pure hell. This is why we inhabit a remote neighborhood of
| the galaxy. You can extrapolate that most spiral galaxies are
| like that and only a small sliver of them are "in play".
|
| Earth won multiple jackpot lotteries in a row, and that's only
| the variables we are aware of:
|
| * Right-sized star
|
| * Right-sized planet
|
| * Not too far and not to close to the star
|
| * Not too little and not too much water
|
| * Oxygen
|
| * Iron core (magnetic field protects from radiation)
|
| * Right-sized moon (keeps rotation stable, tides)
|
| * Gas giants absorbing a lot of debris coming our away
|
| * A single-star system, with nearly circular, stable planetary
| orbits (very rare)* ... and so on
|
| Yes, I know there are permutations that might also work, but in
| general it does not look good for spontaneous life.I like a
| theory that states that the Universe is just the right size
| where one single Earth has only a single probability to spring
| up randomly. The Maker covered their tracks well, if you
| believe in higher intelligence.
| jhedwards wrote:
| This doesn't seem like the right calculation to me. Doing
| some quick lookups, I find that the number of galaxies in the
| universe is estimated to be between 200 billion and 2
| trillion. As for stars in a galaxy, there are around 100
| billion stars in the milky way galaxy, so lets go with that.
|
| If we guess that only about a quarter of any given galaxy is
| potentially habitable, that leaves 25 billion possibilities
| per galaxy. If we go with that and a middling estimate for
| the number of galaxies then we have maybe (25 billion * 1
| trillion) stars, which is a number so big I don't even know
| how to say or comprehend it.
|
| Even if we take an extremely conservative view that each
| galaxy only has at most 25 stars with potentially habitable
| planets (cutting the 1/4 galaxy estimate down by a factor of
| one BILLION) then we are still left with 25 trillion
| possibilities, which seems like a pretty good chance to me.
| lowbloodsugar wrote:
| Space... is big. Really big. You just won't believe how
| vastly hugely mindbogglingly big it is...
| fragmede wrote:
| Aka Drake's equation, with sufficiently large numbers,
| gives a decent chance of habitability. We just don't know
| what the numbers really are. Those big enough numbers with
| small enough other names make for a low enough number that
| it might as well be zero since we can't observe or interact
| with them.
| czzr wrote:
| Oxygen doesn't belong on that list, I think - the earth's
| oxygen was made by the first living things.
| bongodongobob wrote:
| The didn't make the oxygen, they unlocked it from various
| molecules and minerals etc. It had to be here first.
| greiskul wrote:
| But I don't think there is anything special on there
| being oxygen in the cloud of gas that formed the solar
| system. The distribution of elements following a
| supernova probably follows some law, and oxygen is low
| enough on the periodic table that probably quite a bit of
| it is expected.
| czzr wrote:
| True - oxygen is very abundant, though, so its presence
| is not surprising.
| White_Wolf wrote:
| You are making a few (?wrong) assumptions here:
|
| - that we are first
|
| - oxygen is needed for all life forms
|
| - the habitable zone that is ideal for us the only one that
| can give birth to intelligent life
|
| - magnetic field is needed for life to exist/radiation kills
| off all life
| layer8 wrote:
| It's a game of numbers. There may be 10^ _n_ opportunities for
| life potentially forming, with the average likelihood for life
| actually forming being 10^- _m_ for each. The question is, is
| _n_ (much) larger than _m_ , or vice versa? We really have no
| idea, in particular with regard to _m_. It doesn't help if _n_
| is 100 when _m_ may be 1000. And the human brain is really bad
| at estimating such likelihoods.
| floatrock wrote:
| So an orphan star is one that's been ejected from its galaxy.
|
| If one of those stars had a planet with something capable of
| "gazing up at the night sky", does that mean their sky would be
| empty compared to our own?
| NKosmatos wrote:
| No, their night sky would be more or less like our own. There
| would be other stars and galaxies visible, it's just that this
| planet (along with the other planets of this orphan star) would
| be outside of a galaxy and they would be travelling the
| universe in the "void" between galaxies.
|
| Being outside a galaxy doesn't mean that you have a black night
| sky, it just means that you're a little bit further away from
| other stars and you're moving in the interstellar medium.
| klyrs wrote:
| We can see the Milky Way in clear conditions; with light
| pollution we can only see the brightest stars. Perhaps an
| orphan star would have a darker sky, without a clear view of
| a galactic superstructure without using a telescope?
| floatrock wrote:
| So my understanding is most of the stars that fill our sky
| are stars inside our milky way and nearby. "The Milky Way"
| smudge we can see in a dark sky is the collective effort of
| all the far-off milky way stars.
|
| I assume some of the 'stars' we can see with the naked eye
| are actually galaxies, but I assume that's a small
| percentage.
|
| Our closest galaxy, Andromeda, appears barely as a smudge to
| the naked eye.
|
| I guess my question is more about how far away from their
| home galaxies are these orphan stars, expressed as a
| percentage of a hypothetical planet's sky-cover.
|
| eg we see the milky way as a band because we're inside the
| galactic plane... would these orphan planets see their home
| galaxy as a fainter band because they've been ejected still
| in the galactic plane? Would they see part of the sky covered
| and part of the sky blank because they're outside their home
| galactic plane? Are they still close enough to their home
| galaxy that they're still surrounded by enough stars to fill
| the sky, or would the star density in their skies be
| seasonal?
|
| I think it would be fun to speculate on different
| hypothetical cultural evolutions of different kinds of night
| sky configurations, like "winter is when our planet's night
| sees our home galaxy, so winter is when the gods send their
| nightlumination down on us" etc.
| dwaltrip wrote:
| I don't think this is correct. Most of the stars we see in
| the night sky are close by in our neighborhood of the Milky
| Way. Being in the void between galaxies, there wouldn't be
| many neighboring stars close to the orphan stars. This would
| make their night sky much emptier to the human eye.
| NKosmatos wrote:
| For sure their sky would be a lot lot emptier, but I don't
| think it would be pitch black.
| NKosmatos wrote:
| High resolution view:
| https://sky.esa.int/esasky/?target=49.6809329688%2041.614370...
| ourmandave wrote:
| Euclid is bringing together 14+ countries and damn near every
| related field.
|
| Warms my little nerd heart.
|
| _Euclid Consortium
|
| To date 14 European countries contribute to EC activities
| (Austria, Belgium, Denmark, Finland, France, Germany, Italy, the
| Netherlands, Norway, Portugal, Romania, Spain, Switzerland and
| United Kingdom).
|
| Canada and USA through NASA and few US laboratories as well as
| few Japanese laboratories are also contributing and members of
| the Euclid Consortium.
|
| In total, more than 2600 members were or are registered in the EC
| (status early 2023), of which more than 1000 are researchers in
| astrophysics, cosmology, theoretical physics, and particle
| physics.
|
| More than 200 laboratories covering all fields in astrophysics,
| cosmology, theoretical physics, high energy, particle physics and
| space science that are relevant for the Euclid missions are
| contributing to Euclid._
|
| https://www.euclid-ec.org/consortium/about-ec/
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