20 ms·

Astronomers reveal first image of the black hole at the heart of our galaxy

786 points by sohkamyung 4y ago

jack-bodine 4y ago
This announcement was released simultaneously with 6 papers that use the newly released data. They are linked in the bottom of the press release and are definitely worth checking out.
- wumpus 4y ago
  10 papers total in this batch.
mescaline 4y ago
> Because the black hole is about 27,000 light-years away from Earth, it appears to us to have about the same size in the sky as a donut on the Moon. I'm still sad we can't post donut emojis here. This place sucks.
- deleted 4y ago
  [deleted]
22SAS 4y ago
This is some great work, kudos to the researchers working in the Event Horizon Telescope team.
mabbo 4y ago
> “We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity," And ten thousand physicists sighed disappointingly.
- markus_zhang 4y ago
  Just curious but why?
  - onceiwasthere 4y ago
    They want an exciting disruption to current theory.
    - BurningFrog 4y ago
      Basically they're bored/want mysteries to solve.
      - zeven7 4y ago
        tbf, there is already a mystery to solve. This just means we have no new information to help us solve it.
      - ohgodplsno 4y ago
        We're kind of at a dead end between both leading theories. A counterexample to either of them would mean that we got it wrong somewhere, and might help us figure out where, potentially unlocking more later. You wouldn't be surprised if your door opened just as usual when you put your key in the lock. The day it starts jamming however, you get very interested.
    - GuB-42 4y ago
      Side note: Einstein didn't believe in black holes, at least initially. Black holes are a solution to the general relativity equations, but Einstein thought they were just a mathematical quirk, and that in real life, they wouldn't have been able to form. So ever time someone says "Einstein was right" when talking about black holes, then no. He was right about general relativity, but he was wrong about the existence of black holes.
  - _joel 4y ago
    Many papers/authors postulating something different to what Einstein did?
  - adgjlsfhk1 4y ago
    GR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.
- mhandley 4y ago
  Any evidence supporting general relativity at these scales is presumably also evidence in favour of dark matter actually being matter, as opposed to gravitational theory needing modification. Seems like we can still learn quite a bit from ruling out alternatives, even if it's not the quick answer we might like.
  - nerdponx 4y ago
    Why is that the case?
    - cozzyd 4y ago
      Well maybe it's more evidence against MOND-like theories explaining dark matter, but those already have little buy-in nowadays.
  - monocasa 4y ago
    The Schwarzschild radius of a 4M solar mass black hole like Sagittarius A* is only (lol) about 7M km. Most of the MOND theories I've seen are about fall off curves at very large distances (ie. galatic scales) being more complex than GR suggests, so I'm not sure this is really proof either way. (And I say this as not a MOND adherent).
- ISL 4y ago
  Gravitational physicist here. Every time we look in a new place and see that GR still works, it is pretty amazing. Part of this is the fact that everyone in the field works very hard to find a crack in GR's armor, and so far it has resisted everyone. The other part is that GR has a romantic beauty to it, both in structure and in predictions. Each time GR matches reality in a new context, the feeling is akin to watching a beautiful sunrise on a summer's morning. You've seen it before, but darn if it isn't pretty.
  - zeven7 4y ago
    It seems the common expectation is that GR is more likely to be the theory that needs to be modified the most - or more or less tossed out and replaced with a quantum theory of gravity. Is it possible that GR is just "right" and QM needs to be modified to fit into it?
    - ISL 4y ago
      Whenever we learn more about the connections between GR and the rest of physics, the early corrections are likely to appear as "GR+new stuff" or "QM+new stuff". Both theories have enough predictive power that we'll hang on to them as effective theories for the rest of humanity's existence. That said, the mathematical fundamentals of GR do not directly incorporate notions of the uncertainty principle. That fact alone, I believe, means that GR is an incomplete description of space/time/physics.
      - raattgift 4y ago
        Just to cause trouble, since we're straying far far from today's presentations (except arguably UCL's Z. Younsi in the ongoing ESO Q&A panel). :-) Can we write down the uncertainty principle in covariant form? Maybe! There is active theoretical work ongoing (e.g.) <https://arxiv.org/abs/2110.15951v2 https://arxiv.org/abs/2110.15951v2> ("... a geometric formalism for the generalised uncertainty principle which is covariant and connects features of the underlying geometry with the deformation of canonical commutator relations ... [and] an elegant interpretation for the standard dispersion relation p^2=−m^2: it describes flat spacetime in the Milne coordinates, with rest mass m giving the measure of geodesic length from origin").
- deleted 4y ago
  [deleted]
api 4y ago
I'm looking forward to JWST shots of stuff like this.
- imglorp 4y ago
  Yes, IR better penetrates the dust cloud hiding Sgr A*, so here's hoping.
  - nuccy 4y ago
    The EHT reveals the black hole shadow of about 50 micro-arcseconds [1], while JWST has resolution of about 0.1 arcsec [2], thus resolution of JWST is more than 2000 worse. It is physically impossible (regardless of the exposure time) for JWST to resolve Sgr A*. 1. https://physicsworld.com/wp-content/uploads/2022/05/First-SGR-A-results.jpg https://physicsworld.com/wp-content/uploads/2022/05/First-SG... 2. https://webb.nasa.gov/content/about/faqs/facts.html https://webb.nasa.gov/content/about/faqs/facts.html
    - imglorp 4y ago
      Interesting, thank you.
- wthomp 4y ago
  Unfortunately JWST won’t come close to being able to resolve Sgr A*. They measured its diameter in micro-arcseconds, whereas JWST’s limiting resolution will be measured in 10s-100s of milli-arcseconds.
  - Cthulhu_ 4y ago
    And would it even be able to see past the dust clouds and stars and stuff in front of it? I mean if they could, they could do another longer term observation like from that clip where you can see stars swishing around it.
    - dotnet00 4y ago
kloch 4y ago
One of the findings they announced at the press conference is that the spin of the black hole is not aligned with the galactic plane but is tilted "towards us" so that it is viewed face on. How unexpected is that?
- deleted 4y ago
  [deleted]
- zeven7 4y ago
  For quasars, don't the beams shoot out of the poles? Let's hope our nearby buddy doesn't become that active.
  - raattgift 4y ago
    There is vanishingly small likelihood of Sgr A* becoming active (in the sense of developing highly luminous structures nearby it). There is little in the central parsec to feed it, and it is low in mass for a central black hole. There is a lot of astronomical hunting to be done to find the weak polar jet from Sgr A*. We only look down on its north pole approximately. Extending the spin axis of Sgr A* could miss our solar system by thousands of light years. A polar jet, moreover, can be slightly unaligned from the extended spin axis, and over a 27 kilolightyear distance, that can be even more significant. Finally, we don't know whether the spin axis of the black hole will keep pointing roughly towards us, or whether it sweeps through (up or down) or around the midplane of the galaxy (or on what time scale such "precession", if any, occurs: for all we know, in a few years we might have an image that evidences an Earth-based view almost perpendicular to the spin axis).
    - quasarj 4y ago
      So I have a question about that.. I thought it would only have an accretion disk if it was active. So what gives? I guess I'm wrong? What constitutes "active" if not "stuff is falling in"?
      - raattgift 4y ago
jackallis 4y ago
ithought this was old news from couple of years ago, did i miss something?
- pdabbadabba 4y ago
  The previous image was of M87.[1] The new one is of Sagittarius A*, which is the black hole at the center of our own galaxy. [1] https://www.nasa.gov/mission_pages/chandra/news/black-hole-image-makes-history/ https://www.nasa.gov/mission_pages/chandra/news/black-hole-i...
  - Aardwolf 4y ago
    I also remember this were photos of the milky ways black hole several years ago, am mixing two memories or did news articles then also talk about Sagittarius A*?
- deleted 4y ago
  [deleted]
- m-watson 4y ago
  That was a different black hole that is further away. This black hole is much closer in the center of our galaxy. So now we have pictures of 2 black holes to compare!
daniel-thompson 4y ago
Very interesting. The previously-released M87 image had just a single "shadow", but this one (of Sag A*) has multiple bright "lumps". Maybe it's in the linked papers which I haven't gotten to yet, but why the difference? Is it due to the observation method or does it reflect a real difference? Or both?
- deleted 4y ago
  [deleted]
- misja111 4y ago
  Yeah I was wondering the same. From the M87's images I understood that the bright part of the ring was moving towards us, that's why it was brighter. But with this explanation, how can there be 3 bright lumps then on Sag A's ring ..
  - adgjlsfhk1 4y ago
    I think it is just that this is an extremely noisy image.
- fesoliveira 4y ago
  From the announcement presentation, this happened due to this image being an average of many, many different images. Due to it's size, the motion of the accreting material around SgtA* moves much, much faster relative it than the material around M87. While the accreting material around both BHs move at similar speeds, M87 is about 2000x more massive than SgtA. Due to that, the material around M87 takes weeks to orbit it, while the material around SgtA takes hours. Since each data point can be minutes or hours apart, the final image for a single data point can vary greatly between other measurements, and thus the need to average everything. To put things in perspective, we just confirmed through this image that SgtA*'s shadow is about the size of the orbit of Mercury around the Sun. M87's shadow, on the other hand, has a radius larger than the distance of the Voyager probe to the Sun.
  - daniel-thompson 4y ago
murat124 4y ago
This image apparently has not captured as much attention as the image of M87, but anyway, I have a question, maybe someone with the knowledge can answer: Between the images of M87 and Sgr A, one noticeable difference is that the image of M87 appears to have a single cluster of light "below" the blackhole whereas the image of Sgr A has three surrounding the blackhole. Is this because of the mass and spin differences between the two blackholes?
- nuccy 4y ago
  Likely it is not about the mass, but about the arrangement of clumps of matter circling around the super massive black holes in the accretion disk. During the presentation they speak about much shorter time-scales for Sgr A* in comparison with M87, saying that for Sgr A* they were "making the image while it was changing" [1]. Also see other variations of the image (many teams analyzed data independently) here [2]. 1. https://www.youtube.com/watch?v=rIQLA6lo6R0&t=1930s https://www.youtube.com/watch?v=rIQLA6lo6R0&t=1930s 2. https://physicsworld.com/wp-content/uploads/2022/05/First-SGR-A-results.jpg https://physicsworld.com/wp-content/uploads/2022/05/First-SG... from https://iopscience.iop.org/article/10.3847/2041-8213/ac6429 https://iopscience.iop.org/article/10.3847/2041-8213/ac6429
- ehsankia 4y ago
  > This image apparently has not captured as much attention as the image of M87 To be fair, to most non-scientific people the two photos look basically the same, and "orange halo" kinda loses it's appeal quickly
- edgyquant 4y ago
  The first image of a black hole is cool to everyone, an image of a black hole in the center of the Galaxy is cool to a vastly smaller group I’d imagine.
dredmorbius 4y ago
There seem to be numerous submissions of this topic. This thread seems to be the leading one: Astronomers Reveal First Image of the Black Hole at the Heart of Our Galaxy https://public.nrao.edu/news/astronomers-reveal-first-image-of-the-black-hole-at-the-heart-of-our-galaxy/ https://public.nrao.edu/news/astronomers-reveal-first-image-... (https://news.ycombinator.com/item?id=31353677 https://news.ycombinator.com/item?id=31353677) Others, as of submitting this comment: https://www.eso.org/public/news/eso2208-eht-mw/ https://www.eso.org/public/news/eso2208-eht-mw/ (https://news.ycombinator.com/item?id=31353692 https://news.ycombinator.com/item?id=31353692) https://public.nrao.edu/news/astronomers-reveal-first-image-of-the-black-hole-at-the-heart-of-our-galaxy/ https://public.nrao.edu/news/astronomers-reveal-first-image-... (https://news.ycombinator.com/item?id=31353677 https://news.ycombinator.com/item?id=31353677) https://www.youtube.com/watch?v=rIQLA6lo6R0 https://www.youtube.com/watch?v=rIQLA6lo6R0 (https://news.ycombinator.com/item?id=31353643 https://news.ycombinator.com/item?id=31353643) https://www.youtube.com/watch?v=4Ws0iPDSqI4 https://www.youtube.com/watch?v=4Ws0iPDSqI4 (https://news.ycombinator.com/item?id=31353587 https://news.ycombinator.com/item?id=31353587) https://www.nsf.gov/news/news_summ.jsp?cntn_id=305028&org=NSF&from=news https://www.nsf.gov/news/news_summ.jsp?cntn_id=305028&org=NS... (https://news.ycombinator.com/item?id=31353583 https://news.ycombinator.com/item?id=31353583) https://nitter.kavin.rocks/ehtelescope/status/1524717272903741442 https://nitter.kavin.rocks/ehtelescope/status/15247172729037... (https://news.ycombinator.com/item?id=31353547 https://news.ycombinator.com/item?id=31353547) https://www.cnet.com/science/space/watch-live-astronomers-reveal-groundbreaking-result-of-milky-ways-black-hole/ https://www.cnet.com/science/space/watch-live-astronomers-re... (https://news.ycombinator.com/item?id=31353480 https://news.ycombinator.com/item?id=31353480) https://beta.nsf.gov/blackholes https://beta.nsf.gov/blackholes (https://news.ycombinator.com/item?id=31353474 https://news.ycombinator.com/item?id=31353474) https://www.youtube.com/watch?v=rIQLA6lo6R0 https://www.youtube.com/watch?v=rIQLA6lo6R0 (https://news.ycombinator.com/item?id=31353463 https://news.ycombinator.com/item?id=31353463) https://www.nsf.gov/news/news_summ.jsp?cntn_id=305148 https://www.nsf.gov/news/news_summ.jsp?cntn_id=305148 (https://news.ycombinator.com/item?id=31353757 https://news.ycombinator.com/item?id=31353757) https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy https://eventhorizontelescope.org/blog/astronomers-reveal-fi... (https://news.ycombinator.com/item?id=31353786 https://news.ycombinator.com/item?id=31353786) https://www.nytimes.com/2022/05/12/science/black-hole-photo.html https://www.nytimes.com/2022/05/12/science/black-hole-photo.... (https://news.ycombinator.com/item?id=31353823 https://news.ycombinator.com/item?id=31353823) https://www.quantamagazine.org/black-hole-image-reveals-sagittarius-a-20220512/ https://www.quantamagazine.org/black-hole-image-reveals-sagi... (https://news.ycombinator.com/item?id=31353874 https://news.ycombinator.com/item?id=31353874) https://www.bbc.co.uk/news/science-environment-61412463 https://www.bbc.co.uk/news/science-environment-61412463 (https://news.ycombinator.com/item?id=31353939 https://news.ycombinator.com/item?id=31353939) https://news.ycombinator.com/item?id=31353221 https://news.ycombinator.com/item?id=31353221
fasteddie31003 4y ago
I am very skeptical of the Event Horizon Telescope (EHT) images because they are not following a scientific method that results in a true representative image of their target. In my opinion astronomy is jumping the shark with these images by making this a big PR stunt. I've looked at their methods for their earlier images and they seem to be hunting for a circle that looks like a black hole in their data. The EHT's full imaging stack has never been calibrated by looking at a known celestial body to compare images to validate their algorithms. They have calibrated their signals from results of other instruments, but their imaging algorithms change to fit their wanted results. This is my biggest problem with their approach. Anyone can modify algorithms of any arbitrary data to get an image of a glowing circle. A better method that shows a more true image would be to calibrate their imaging algorithms against a known celestial body to make sure their techniques produced comparable results from other instruments. Then they should have taken their calibrated imaging algorithms and gave it data from their target. I'd have more confidence in the EHT if they would not change their imaging algorithms across images and give a side-by-side comparison of a known celestial body that other radio telescopes have imaged to verify their whole imaging stack. To me this a just a big PR stunt and I'm very skeptical of their image.
- wumpus 4y ago
  Didn’t I already reply to you weeks ago about a similar comment? Now you can read the actual papers which explain in detail why your comment is incorrect.
  - fasteddie31003 4y ago
    I did read them and I'm not satisfied with their methods.
    - wumpus 4y ago
      You read the 10 just published papers? Impressive.
    - Mehringotio 4y ago
      Either you are an expert in this field than it should be you who writes a clear argument and present it or you are not an expert. Aren't they are peer reviewed? What is your expertise in astrophysics?
jrgd 4y ago
I find the whole thing amazing and captivating - yet the image is … huh … slightly underwhelming. It looks like some gaussian blurred random image. I wish it could be the kind of crisp image JWST ‘sent’. It’s difficult to force oneself to not romanticise these un-visible things based on artists visualisation we got accustomed to.
- kloch 4y ago
  It's actually one of the sharpest images ever made - in terms of angular resolution. The Sag.A* ring is about 51 microarcseconds in diameter. The EHT has a theoretical resolution of ~25 micro arcseconds. For comparison NirCam on Webb has a pixel resolution of 70 miliarcseconds (about 2800 times worse resolution than EHT). The reason it looks blurry is that the black hole features are close to the resolution of EHT so it's only a dozen or so pixels worth of information enlarged to typical image size. EHT is essentially a radio telescope with a dish the size of the Earth. The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth.
  - mabbo 4y ago
    > The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth. Would it be possible to use the same trick in space? IE: get a baseline the diameter of Earth's orbit (roughly)?
    - kloch 4y ago
      For Interferometry to work the data from different baselines has to be collected at the same time so waiting 6 months does not help. Spacecraft could theoretically be used to extend the baselines but the volume of data to be transferred is prohibitive with current spacecraft comm tech. Even on Earth they resort to shipping cases of hard drives instead of transferring over the Internet. One technique where simply waiting 6 months works very well is in measuring parallax. The Gaia spacecraft takes advantage of this.
yawz 4y ago
> EHT team members talk about a sharpness of vision akin to being able to see a bagel on the surface of the Moon. This is truly amazing!
- emerged 4y ago
- solarist 4y ago
  Math actually checks out: https://www.wolframalpha.com/input?i=diameter+of+moon+%2F+0.52+degrees+*+51+microarcseconds https://www.wolframalpha.com/input?i=diameter+of+moon+%2F+0.... ~= 9 cm object on the moon Google says donuts are 12-14 cm in length on average…
- nojonestownpls 4y ago
  Scientists discover a bagel on the surface of the Moon! Search for black hole ends with a bagel hole?! [Become a paid subscriber to read the full story.]
  - tomjakubowski 4y ago
    Your second headline is straight out of a recent movie (rot13: "rirelguvat")
uwagar 4y ago
tbh the image isnt inspiring. kinda like a low res computer simulation.
- tjpnz 4y ago
  It's an object 26k light years from Earth and emits no light. That they were able to capture an image at all is both a scientific and technological triumph.
  - uwagar 4y ago
    i remember the gravitational wave detection. billions of dollars spent for some bleep-bloops.
_joel 4y ago
Anton Petrov is doing a good rundown on youtube now
neals 4y ago
So, what kept us from pointing a camera in that direction and snapping this picture up until now?
- the8472 4y ago
  We have done so many times over the years. But their resolution is only good enough to show the stars in the vicinity, not the details of the accretion disc. https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Sgr...
anothernewdude 4y ago
Yeah, we know. We've already seen this image.
- evanb 4y ago
  You might be thinking of the image of M87 from a few years ago. M87 is in a different galaxy. This image is of Sag A*, the black hole at the center of the Milky Way.
wthomp 4y ago
For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel from Hubble’s wide field camera 3: https://twitter.com/alex_parker/status/1116070667068170240?s=21&t=5NM9DEiOYb8U3LVWFI6otw https://twitter.com/alex_parker/status/1116070667068170240?s... JWST will have smaller “pixels” but is in the same ballpark.
- hammock 4y ago
  How sharp do we expect an infinite-res picture to be?
  - fsh 4y ago
    The resolution of these telescopes is limited by diffraction, not by the number of pixels on the sensors. The achievable angular resolution is roughly the wavelength divided by the aperture diameter [1]. JWST works in the few µm wavelength range and has a 6.5 m aperture, such that the angular resolution is ~0.1 arcsec. The EHT works with 1.3 mm wavelength and has an effective aperture of roughly the earth diameter (~13000 km). This leads to an angular resolution of a few ten µarcsec which is more than 1000 times higher than that of JWST. [1] https://en.wikipedia.org/wiki/Angular_resolution https://en.wikipedia.org/wiki/Angular_resolution
    - amelius 4y ago
      Can we invert the diffraction process numerically?
      - adgjlsfhk1 4y ago
        no
      - fsh 4y ago
        No, this is fundamentally impossible. There are infinitely many possible objects that would produce the same blurry image.
NelsonMinar 4y ago
I love this quote, it's great popular science communication. "the brightness and pattern of the gas around Sgr A* was changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail."
Sporktacular 4y ago
I recall the EHT imaging 2 objects back in 2019 - M87 and another black hole. Does anyone remember what that was, or am I mistaken? I thought it was Sagittarius A* back then.
- kloch 4y ago
  They collected data on both back in 2017. It took until now to develop the image processing techniques to account for the rapid changes in the accretion disk around Sag.A*.
  - Sporktacular 4y ago
    Ah, so they didn't release an image of it back then? Or was it just a less precise image? Thought I saw one but can't find it now among all these newly release images. Thanks BTW
    - DiogenesKynikos 4y ago
      They only released the image of M87 back then.
smm11 4y ago
So earth will be sucked down this black hole and shredded how many days from now?
awsrocks 4y ago
aaroninsf 4y ago
Q: why are galaxies like ours so good at golf? A: there's usually a splendid hole in one.
mc4ndr3 4y ago
NHQ 4y ago
This image came out several years ago or I have seen the future.
- bowsamic 4y ago
  What? This is totally new
- sailingparrot 4y ago
  third, slightly more plausible, option: What you have seen a few years ago was the image released of the blackhole at the center of the galaxy M87 [1]. Today's announcement is about the blackhole at the center of our own galaxy. [1]: https://www.nationalgeographic.com/science/article/first-picture-black-hole-revealed-m87-event-horizon-telescope-astrophysics https://www.nationalgeographic.com/science/article/first-pic...
- slimginz 4y ago
  That was the M87 black hole image that came out back in 2019 https://solarsystem.nasa.gov/resources/2319/first-image-of-a-black-hole/ https://solarsystem.nasa.gov/resources/2319/first-image-of-a...
- josu 4y ago
  Yeah, this image is quite old, around 27k years or so.
belter 4y ago
Announcement press conference: "Press conference on Milky Way galaxy discovery from the Event Horizon Telescope collaboration" https://youtu.be/KgvPA9RmEnk https://youtu.be/KgvPA9RmEnk
ramigb 4y ago
Can the smart people in here confirm if we are getting sucked into this someday or not?
- hathym 4y ago
  don't worry, we will destroy the planet before that.
- jepler 4y ago
  On the timescale from now until the sun goes nova, confident "no". Roughly speaking, the sun orbits the galactic center at a velocity of 220km/s. To fall into, or to be sucked into, the central black hole would require the loss of all this velocity, which means applying acceleration to the sun opposite the direction of its orbit. Lots of acceleration. That has to come from somewhere. I suppose there's some extremely tiny amount of drag that occurs due to the sun moving in the interstellar medium, but aside from that there's not a lot that applies acceleration to the sun opposite the direction of its orbit. Really the only other thing that comes to mind are the gravitational waves that are radiated by co-rotating objects. This is the effect that causes close by black holes to eventually come close enough that they merge. But in objects traveling at slower speeds in larger orbits, this effect is also negligible on the scale of billions of years. (These are the gravitational waves observed by LIGO). https://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity#Gravitational_radiation https://en.wikipedia.org/wiki/Two-body_problem_in_general_re...
  - perardi 4y ago
    [pushes up glasses] The Sun is nowhere near massive enough to become supernova. https://en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaustion https://en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaus... It will become a red giant, and then eventually end up a white dwarf.
    - jepler 4y ago
      Thanks for the correction. You're right, current scientific thinking is that the sun is not capable of going "supernova".
coryfklein 4y ago
I'm sorry, I am really confused. Didn't we get "the first picture of the black hole at the center of our galaxy" like 2-3 years ago? I definitely remember seeing a nearly identical photo, and lots of press coverage about a particularly young woman who was closely involved in the project. What that something different?
- black_puppydog 4y ago
  as crazy as it sounds: that black hole was actually in a different galaxy :)
  - infogulch 4y ago
    Funnily enough, M87* is bigger than Sgr A* by about the same factor than it is farther away (~2000x ?), and these effects mostly cancel out so the effective resolution of each is about the same. They chose to image M87* first because there is less dust/gas obstructing the view through intergalactic space to M87 than through the bulk of the milky way disk.
- sgregnt 4y ago
  The image from a few years ago, was taken of a blackhole in a different galaxy.
- ritwikgupta 4y ago
  That image was also captured by the EHT of the supermassive black hole (M87*) at the center of the M87 galaxy. The woman you're thinking of is Dr. Katie Bouman, now faculty at Caltech. She is also listed as an author on this work of imaging Sgr A*.
- dseGH3FETWJJy 4y ago
  Nope, that was a black hole in another galaxy- Messier 87
- deleted 4y ago
  [deleted]
- 4y ago
bholevid34 4y ago
Extremely cool video, "Meet Sgr A*: Zooming into the black hole at the centre of our galaxy": https://www.youtube.com/watch?v=Zml0dZCjaFw https://www.youtube.com/watch?v=Zml0dZCjaFw
muxneo 4y ago
Size of rings prove Einstein's Theory of relativity. This is an amazing work
Maursault 4y ago
Didn't we see this image last April? What is new here? tia
Apocryphon 4y ago
Funnily enough, Arcade Fire released a new album this week, which just happens to have a song entitled Sagittarius A* https://www.youtube.com/watch?v=rAUpD4FchZI https://www.youtube.com/watch?v=rAUpD4FchZI https://genius.com/25770411 https://genius.com/25770411
denton-scratch 4y ago
I am impressed. I have a few ignorant questions: 1. There are three bright blobs on the image; I assume they are the same object, behind the BH. What are they/is it? They said the image was averaged; so presumably whatever the blobs are wasn't moving? 2. Is it correct that the rest of the ring, ignoring the three blobs, is the far side of the accretion disk? Why can't I see this side of the accretion disk? 3. According to the article, at least one submillimeter telescope was important. But submillimeter is infrared, isn't it? I thought infrared was blocked by dust, and if there's one thing there's a lot of at the centre of the galaxy, it's dust? [Edit] Questions 1 and two were prompted by this remark in the article: "The new view captures light bent by the powerful gravity of the black hole" The only "light" I can see is a ring with blobs in it; that's why I suppose the ring in the image is not the accretion disk, at least, not as viewed from the pole. Most other commenters here assume (or know) that it is the accretion disk, and we are looking at a pole. But if that is indeed the accretion disk, then that isn't light that's been bent by the gravity of the black hole. Perhaps the explanation is that many other commenters haven't actually read the article, possibly because they already know the story.
- kryptn 4y ago
  > 3. According to the article, at least one submillimeter telescope was important. But submillimeter is infrared, isn't it? I thought infrared was blocked by dust, and if there's one thing there's a lot of at the centre of the galaxy, it's dust? It's the opposite actually! Infrared light is able to go through dust. > Another reason [to look at the universe in the infrared] is because stars and planets form in clouds of gas and dust, and this dust obscures our view. Infrared light penetrates these clouds and allows us to see inside. https://www.nasa.gov/content/goddard/webb-conversations-its-all-about-infrared-why-build-the-james-webb-space-telescope https://www.nasa.gov/content/goddard/webb-conversations-its-...
  - denton-scratch 4y ago
    OK, that explains that; thanks.
- whitesilhouette 4y ago
nyc111 4y ago
Matt Strassler: «The details of the reconstructed image depend on exactly what assumptions are made.» https://profmattstrassler.com/2022/05/12/in-our-galaxys-center-a-tiny-monster/ https://profmattstrassler.com/2022/05/12/in-our-galaxys-cent... What does this mean? If they assembled an image to fit their assumptions, that would be circular reasoning. I don't understand.
storedsun 4y ago
iliketrains 4y ago
This is incredible! Veritasium has a nice video explaining how those images were obtained and what they mean: https://www.youtube.com/watch?v=Q1bSDnuIPbo https://www.youtube.com/watch?v=Q1bSDnuIPbo
sidcool 4y ago
I still can't wrap my head around the fact that black holes are real things. And GR predicts them so accurately.
leommoore 4y ago
There is something cool about being able to see something so powerful in the far reaches of space as it looked 27,000 years ago.

786 points by sohkamyung 4y ago

This announcement was released simultaneously with 6 papers that use the newly released data. They are linked in the bottom of the press release and are definitely worth checking out.

wumpus 4y ago
10 papers total in this batch.

mescaline 4y ago

> Because the black hole is about 27,000 light-years away from Earth, it appears to us to have about the same size in the sky as a donut on the Moon. I'm still sad we can't post donut emojis here. This place sucks.

deleted 4y ago
[deleted]

22SAS 4y ago

This is some great work, kudos to the researchers working in the Event Horizon Telescope team.

mabbo 4y ago

> “We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity," And ten thousand physicists sighed disappointingly.

markus_zhang 4y ago
Just curious but why?
- onceiwasthere 4y ago
  They want an exciting disruption to current theory.
  - BurningFrog 4y ago
    Basically they're bored/want mysteries to solve.
    - zeven7 4y ago
      tbf, there is already a mystery to solve. This just means we have no new information to help us solve it.
    - ohgodplsno 4y ago
      We're kind of at a dead end between both leading theories. A counterexample to either of them would mean that we got it wrong somewhere, and might help us figure out where, potentially unlocking more later. You wouldn't be surprised if your door opened just as usual when you put your key in the lock. The day it starts jamming however, you get very interested.
  - GuB-42 4y ago
    Side note: Einstein didn't believe in black holes, at least initially. Black holes are a solution to the general relativity equations, but Einstein thought they were just a mathematical quirk, and that in real life, they wouldn't have been able to form. So ever time someone says "Einstein was right" when talking about black holes, then no. He was right about general relativity, but he was wrong about the existence of black holes.
- _joel 4y ago
  Many papers/authors postulating something different to what Einstein did?
- adgjlsfhk1 4y ago
  GR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.
mhandley 4y ago
Any evidence supporting general relativity at these scales is presumably also evidence in favour of dark matter actually being matter, as opposed to gravitational theory needing modification. Seems like we can still learn quite a bit from ruling out alternatives, even if it's not the quick answer we might like.
- nerdponx 4y ago
  Why is that the case?
  - cozzyd 4y ago
    Well maybe it's more evidence against MOND-like theories explaining dark matter, but those already have little buy-in nowadays.
- monocasa 4y ago
  The Schwarzschild radius of a 4M solar mass black hole like Sagittarius A* is only (lol) about 7M km. Most of the MOND theories I've seen are about fall off curves at very large distances (ie. galatic scales) being more complex than GR suggests, so I'm not sure this is really proof either way. (And I say this as not a MOND adherent).
ISL 4y ago
Gravitational physicist here. Every time we look in a new place and see that GR still works, it is pretty amazing. Part of this is the fact that everyone in the field works very hard to find a crack in GR's armor, and so far it has resisted everyone. The other part is that GR has a romantic beauty to it, both in structure and in predictions. Each time GR matches reality in a new context, the feeling is akin to watching a beautiful sunrise on a summer's morning. You've seen it before, but darn if it isn't pretty.
- zeven7 4y ago
  It seems the common expectation is that GR is more likely to be the theory that needs to be modified the most - or more or less tossed out and replaced with a quantum theory of gravity. Is it possible that GR is just "right" and QM needs to be modified to fit into it?
  - ISL 4y ago
    Whenever we learn more about the connections between GR and the rest of physics, the early corrections are likely to appear as "GR+new stuff" or "QM+new stuff". Both theories have enough predictive power that we'll hang on to them as effective theories for the rest of humanity's existence. That said, the mathematical fundamentals of GR do not directly incorporate notions of the uncertainty principle. That fact alone, I believe, means that GR is an incomplete description of space/time/physics.
    - raattgift 4y ago
      Just to cause trouble, since we're straying far far from today's presentations (except arguably UCL's Z. Younsi in the ongoing ESO Q&A panel). :-) Can we write down the uncertainty principle in covariant form? Maybe! There is active theoretical work ongoing (e.g.) <https://arxiv.org/abs/2110.15951v2 https://arxiv.org/abs/2110.15951v2> ("... a geometric formalism for the generalised uncertainty principle which is covariant and connects features of the underlying geometry with the deformation of canonical commutator relations ... [and] an elegant interpretation for the standard dispersion relation p^2=−m^2: it describes flat spacetime in the Milne coordinates, with rest mass m giving the measure of geodesic length from origin").
deleted 4y ago
[deleted]

api 4y ago

I'm looking forward to JWST shots of stuff like this.

imglorp 4y ago
Yes, IR better penetrates the dust cloud hiding Sgr A*, so here's hoping.
- nuccy 4y ago
  The EHT reveals the black hole shadow of about 50 micro-arcseconds [1], while JWST has resolution of about 0.1 arcsec [2], thus resolution of JWST is more than 2000 worse. It is physically impossible (regardless of the exposure time) for JWST to resolve Sgr A*. 1. https://physicsworld.com/wp-content/uploads/2022/05/First-SGR-A-results.jpg https://physicsworld.com/wp-content/uploads/2022/05/First-SG... 2. https://webb.nasa.gov/content/about/faqs/facts.html https://webb.nasa.gov/content/about/faqs/facts.html
  - imglorp 4y ago
    Interesting, thank you.
wthomp 4y ago
Unfortunately JWST won’t come close to being able to resolve Sgr A*. They measured its diameter in micro-arcseconds, whereas JWST’s limiting resolution will be measured in 10s-100s of milli-arcseconds.
- Cthulhu_ 4y ago
  And would it even be able to see past the dust clouds and stars and stuff in front of it? I mean if they could, they could do another longer term observation like from that clip where you can see stars swishing around it.
  - dotnet00 4y ago

kloch 4y ago

One of the findings they announced at the press conference is that the spin of the black hole is not aligned with the galactic plane but is tilted "towards us" so that it is viewed face on. How unexpected is that?

deleted 4y ago
[deleted]
zeven7 4y ago
For quasars, don't the beams shoot out of the poles? Let's hope our nearby buddy doesn't become that active.
- raattgift 4y ago
  There is vanishingly small likelihood of Sgr A* becoming active (in the sense of developing highly luminous structures nearby it). There is little in the central parsec to feed it, and it is low in mass for a central black hole. There is a lot of astronomical hunting to be done to find the weak polar jet from Sgr A*. We only look down on its north pole approximately. Extending the spin axis of Sgr A* could miss our solar system by thousands of light years. A polar jet, moreover, can be slightly unaligned from the extended spin axis, and over a 27 kilolightyear distance, that can be even more significant. Finally, we don't know whether the spin axis of the black hole will keep pointing roughly towards us, or whether it sweeps through (up or down) or around the midplane of the galaxy (or on what time scale such "precession", if any, occurs: for all we know, in a few years we might have an image that evidences an Earth-based view almost perpendicular to the spin axis).
  - quasarj 4y ago
    So I have a question about that.. I thought it would only have an accretion disk if it was active. So what gives? I guess I'm wrong? What constitutes "active" if not "stuff is falling in"?
    - raattgift 4y ago

jackallis 4y ago

ithought this was old news from couple of years ago, did i miss something?

pdabbadabba 4y ago
The previous image was of M87.[1] The new one is of Sagittarius A*, which is the black hole at the center of our own galaxy. [1] https://www.nasa.gov/mission_pages/chandra/news/black-hole-image-makes-history/ https://www.nasa.gov/mission_pages/chandra/news/black-hole-i...
- Aardwolf 4y ago
  I also remember this were photos of the milky ways black hole several years ago, am mixing two memories or did news articles then also talk about Sagittarius A*?
deleted 4y ago
[deleted]
m-watson 4y ago
That was a different black hole that is further away. This black hole is much closer in the center of our galaxy. So now we have pictures of 2 black holes to compare!

daniel-thompson 4y ago

Very interesting. The previously-released M87 image had just a single "shadow", but this one (of Sag A*) has multiple bright "lumps". Maybe it's in the linked papers which I haven't gotten to yet, but why the difference? Is it due to the observation method or does it reflect a real difference? Or both?

deleted 4y ago
[deleted]
misja111 4y ago
Yeah I was wondering the same. From the M87's images I understood that the bright part of the ring was moving towards us, that's why it was brighter. But with this explanation, how can there be 3 bright lumps then on Sag A's ring ..
- adgjlsfhk1 4y ago
  I think it is just that this is an extremely noisy image.
fesoliveira 4y ago
From the announcement presentation, this happened due to this image being an average of many, many different images. Due to it's size, the motion of the accreting material around SgtA* moves much, much faster relative it than the material around M87. While the accreting material around both BHs move at similar speeds, M87 is about 2000x more massive than SgtA. Due to that, the material around M87 takes weeks to orbit it, while the material around SgtA takes hours. Since each data point can be minutes or hours apart, the final image for a single data point can vary greatly between other measurements, and thus the need to average everything. To put things in perspective, we just confirmed through this image that SgtA*'s shadow is about the size of the orbit of Mercury around the Sun. M87's shadow, on the other hand, has a radius larger than the distance of the Voyager probe to the Sun.
- daniel-thompson 4y ago

murat124 4y ago

This image apparently has not captured as much attention as the image of M87, but anyway, I have a question, maybe someone with the knowledge can answer: Between the images of M87 and Sgr A, one noticeable difference is that the image of M87 appears to have a single cluster of light "below" the blackhole whereas the image of Sgr A has three surrounding the blackhole. Is this because of the mass and spin differences between the two blackholes?

nuccy 4y ago
Likely it is not about the mass, but about the arrangement of clumps of matter circling around the super massive black holes in the accretion disk. During the presentation they speak about much shorter time-scales for Sgr A* in comparison with M87, saying that for Sgr A* they were "making the image while it was changing" [1]. Also see other variations of the image (many teams analyzed data independently) here [2]. 1. https://www.youtube.com/watch?v=rIQLA6lo6R0&t=1930s https://www.youtube.com/watch?v=rIQLA6lo6R0&t=1930s 2. https://physicsworld.com/wp-content/uploads/2022/05/First-SGR-A-results.jpg https://physicsworld.com/wp-content/uploads/2022/05/First-SG... from https://iopscience.iop.org/article/10.3847/2041-8213/ac6429 https://iopscience.iop.org/article/10.3847/2041-8213/ac6429
ehsankia 4y ago
> This image apparently has not captured as much attention as the image of M87 To be fair, to most non-scientific people the two photos look basically the same, and "orange halo" kinda loses it's appeal quickly
edgyquant 4y ago
The first image of a black hole is cool to everyone, an image of a black hole in the center of the Galaxy is cool to a vastly smaller group I’d imagine.

dredmorbius 4y ago

There seem to be numerous submissions of this topic. This thread seems to be the leading one: Astronomers Reveal First Image of the Black Hole at the Heart of Our Galaxy https://public.nrao.edu/news/astronomers-reveal-first-image-of-the-black-hole-at-the-heart-of-our-galaxy/ https://public.nrao.edu/news/astronomers-reveal-first-image-... (https://news.ycombinator.com/item?id=31353677 https://news.ycombinator.com/item?id=31353677) Others, as of submitting this comment: https://www.eso.org/public/news/eso2208-eht-mw/ https://www.eso.org/public/news/eso2208-eht-mw/ (https://news.ycombinator.com/item?id=31353692 https://news.ycombinator.com/item?id=31353692) https://public.nrao.edu/news/astronomers-reveal-first-image-of-the-black-hole-at-the-heart-of-our-galaxy/ https://public.nrao.edu/news/astronomers-reveal-first-image-... (https://news.ycombinator.com/item?id=31353677 https://news.ycombinator.com/item?id=31353677) https://www.youtube.com/watch?v=rIQLA6lo6R0 https://www.youtube.com/watch?v=rIQLA6lo6R0 (https://news.ycombinator.com/item?id=31353643 https://news.ycombinator.com/item?id=31353643) https://www.youtube.com/watch?v=4Ws0iPDSqI4 https://www.youtube.com/watch?v=4Ws0iPDSqI4 (https://news.ycombinator.com/item?id=31353587 https://news.ycombinator.com/item?id=31353587) https://www.nsf.gov/news/news_summ.jsp?cntn_id=305028&org=NSF&from=news https://www.nsf.gov/news/news_summ.jsp?cntn_id=305028&org=NS... (https://news.ycombinator.com/item?id=31353583 https://news.ycombinator.com/item?id=31353583) https://nitter.kavin.rocks/ehtelescope/status/1524717272903741442 https://nitter.kavin.rocks/ehtelescope/status/15247172729037... (https://news.ycombinator.com/item?id=31353547 https://news.ycombinator.com/item?id=31353547) https://www.cnet.com/science/space/watch-live-astronomers-reveal-groundbreaking-result-of-milky-ways-black-hole/ https://www.cnet.com/science/space/watch-live-astronomers-re... (https://news.ycombinator.com/item?id=31353480 https://news.ycombinator.com/item?id=31353480) https://beta.nsf.gov/blackholes https://beta.nsf.gov/blackholes (https://news.ycombinator.com/item?id=31353474 https://news.ycombinator.com/item?id=31353474) https://www.youtube.com/watch?v=rIQLA6lo6R0 https://www.youtube.com/watch?v=rIQLA6lo6R0 (https://news.ycombinator.com/item?id=31353463 https://news.ycombinator.com/item?id=31353463) https://www.nsf.gov/news/news_summ.jsp?cntn_id=305148 https://www.nsf.gov/news/news_summ.jsp?cntn_id=305148 (https://news.ycombinator.com/item?id=31353757 https://news.ycombinator.com/item?id=31353757) https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy https://eventhorizontelescope.org/blog/astronomers-reveal-fi... (https://news.ycombinator.com/item?id=31353786 https://news.ycombinator.com/item?id=31353786) https://www.nytimes.com/2022/05/12/science/black-hole-photo.html https://www.nytimes.com/2022/05/12/science/black-hole-photo.... (https://news.ycombinator.com/item?id=31353823 https://news.ycombinator.com/item?id=31353823) https://www.quantamagazine.org/black-hole-image-reveals-sagittarius-a-20220512/ https://www.quantamagazine.org/black-hole-image-reveals-sagi... (https://news.ycombinator.com/item?id=31353874 https://news.ycombinator.com/item?id=31353874) https://www.bbc.co.uk/news/science-environment-61412463 https://www.bbc.co.uk/news/science-environment-61412463 (https://news.ycombinator.com/item?id=31353939 https://news.ycombinator.com/item?id=31353939) https://news.ycombinator.com/item?id=31353221 https://news.ycombinator.com/item?id=31353221

fasteddie31003 4y ago

I am very skeptical of the Event Horizon Telescope (EHT) images because they are not following a scientific method that results in a true representative image of their target. In my opinion astronomy is jumping the shark with these images by making this a big PR stunt. I've looked at their methods for their earlier images and they seem to be hunting for a circle that looks like a black hole in their data. The EHT's full imaging stack has never been calibrated by looking at a known celestial body to compare images to validate their algorithms. They have calibrated their signals from results of other instruments, but their imaging algorithms change to fit their wanted results. This is my biggest problem with their approach. Anyone can modify algorithms of any arbitrary data to get an image of a glowing circle. A better method that shows a more true image would be to calibrate their imaging algorithms against a known celestial body to make sure their techniques produced comparable results from other instruments. Then they should have taken their calibrated imaging algorithms and gave it data from their target. I'd have more confidence in the EHT if they would not change their imaging algorithms across images and give a side-by-side comparison of a known celestial body that other radio telescopes have imaged to verify their whole imaging stack. To me this a just a big PR stunt and I'm very skeptical of their image.

wumpus 4y ago
Didn’t I already reply to you weeks ago about a similar comment? Now you can read the actual papers which explain in detail why your comment is incorrect.
- fasteddie31003 4y ago
  I did read them and I'm not satisfied with their methods.
  - wumpus 4y ago
    You read the 10 just published papers? Impressive.
  - Mehringotio 4y ago
    Either you are an expert in this field than it should be you who writes a clear argument and present it or you are not an expert. Aren't they are peer reviewed? What is your expertise in astrophysics?

jrgd 4y ago

I find the whole thing amazing and captivating - yet the image is … huh … slightly underwhelming. It looks like some gaussian blurred random image. I wish it could be the kind of crisp image JWST ‘sent’. It’s difficult to force oneself to not romanticise these un-visible things based on artists visualisation we got accustomed to.

kloch 4y ago
It's actually one of the sharpest images ever made - in terms of angular resolution. The Sag.A* ring is about 51 microarcseconds in diameter. The EHT has a theoretical resolution of ~25 micro arcseconds. For comparison NirCam on Webb has a pixel resolution of 70 miliarcseconds (about 2800 times worse resolution than EHT). The reason it looks blurry is that the black hole features are close to the resolution of EHT so it's only a dozen or so pixels worth of information enlarged to typical image size. EHT is essentially a radio telescope with a dish the size of the Earth. The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth.
- mabbo 4y ago
  > The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth. Would it be possible to use the same trick in space? IE: get a baseline the diameter of Earth's orbit (roughly)?
  - kloch 4y ago
    For Interferometry to work the data from different baselines has to be collected at the same time so waiting 6 months does not help. Spacecraft could theoretically be used to extend the baselines but the volume of data to be transferred is prohibitive with current spacecraft comm tech. Even on Earth they resort to shipping cases of hard drives instead of transferring over the Internet. One technique where simply waiting 6 months works very well is in measuring parallax. The Gaia spacecraft takes advantage of this.

yawz 4y ago

> EHT team members talk about a sharpness of vision akin to being able to see a bagel on the surface of the Moon. This is truly amazing!

emerged 4y ago
solarist 4y ago
Math actually checks out: https://www.wolframalpha.com/input?i=diameter+of+moon+%2F+0.52+degrees+*+51+microarcseconds https://www.wolframalpha.com/input?i=diameter+of+moon+%2F+0.... ~= 9 cm object on the moon Google says donuts are 12-14 cm in length on average…
nojonestownpls 4y ago
Scientists discover a bagel on the surface of the Moon! Search for black hole ends with a bagel hole?! [Become a paid subscriber to read the full story.]
- tomjakubowski 4y ago
  Your second headline is straight out of a recent movie (rot13: "rirelguvat")

uwagar 4y ago

tbh the image isnt inspiring. kinda like a low res computer simulation.

tjpnz 4y ago
It's an object 26k light years from Earth and emits no light. That they were able to capture an image at all is both a scientific and technological triumph.
- uwagar 4y ago
  i remember the gravitational wave detection. billions of dollars spent for some bleep-bloops.

_joel 4y ago

Anton Petrov is doing a good rundown on youtube now

neals 4y ago

So, what kept us from pointing a camera in that direction and snapping this picture up until now?

the8472 4y ago
We have done so many times over the years. But their resolution is only good enough to show the stars in the vicinity, not the details of the accretion disc. https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:SgrA2021.gif https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Sgr...

anothernewdude 4y ago

Yeah, we know. We've already seen this image.

evanb 4y ago
You might be thinking of the image of M87 from a few years ago. M87 is in a different galaxy. This image is of Sag A*, the black hole at the center of the Milky Way.

wthomp 4y ago

For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel from Hubble’s wide field camera 3: https://twitter.com/alex_parker/status/1116070667068170240?s=21&t=5NM9DEiOYb8U3LVWFI6otw https://twitter.com/alex_parker/status/1116070667068170240?s... JWST will have smaller “pixels” but is in the same ballpark.

hammock 4y ago
How sharp do we expect an infinite-res picture to be?
- fsh 4y ago
  The resolution of these telescopes is limited by diffraction, not by the number of pixels on the sensors. The achievable angular resolution is roughly the wavelength divided by the aperture diameter [1]. JWST works in the few µm wavelength range and has a 6.5 m aperture, such that the angular resolution is ~0.1 arcsec. The EHT works with 1.3 mm wavelength and has an effective aperture of roughly the earth diameter (~13000 km). This leads to an angular resolution of a few ten µarcsec which is more than 1000 times higher than that of JWST. [1] https://en.wikipedia.org/wiki/Angular_resolution https://en.wikipedia.org/wiki/Angular_resolution
  - amelius 4y ago
    Can we invert the diffraction process numerically?
    - adgjlsfhk1 4y ago
      no
    - fsh 4y ago
      No, this is fundamentally impossible. There are infinitely many possible objects that would produce the same blurry image.

NelsonMinar 4y ago

I love this quote, it's great popular science communication. "the brightness and pattern of the gas around Sgr A* was changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail."

Sporktacular 4y ago

I recall the EHT imaging 2 objects back in 2019 - M87 and another black hole. Does anyone remember what that was, or am I mistaken? I thought it was Sagittarius A* back then.

kloch 4y ago
They collected data on both back in 2017. It took until now to develop the image processing techniques to account for the rapid changes in the accretion disk around Sag.A*.
- Sporktacular 4y ago
  Ah, so they didn't release an image of it back then? Or was it just a less precise image? Thought I saw one but can't find it now among all these newly release images. Thanks BTW
  - DiogenesKynikos 4y ago
    They only released the image of M87 back then.

smm11 4y ago

So earth will be sucked down this black hole and shredded how many days from now?

awsrocks 4y ago

aaroninsf 4y ago

Q: why are galaxies like ours so good at golf? A: there's usually a splendid hole in one.

mc4ndr3 4y ago

NHQ 4y ago

This image came out several years ago or I have seen the future.

bowsamic 4y ago
What? This is totally new
sailingparrot 4y ago
third, slightly more plausible, option: What you have seen a few years ago was the image released of the blackhole at the center of the galaxy M87 [1]. Today's announcement is about the blackhole at the center of our own galaxy. [1]: https://www.nationalgeographic.com/science/article/first-picture-black-hole-revealed-m87-event-horizon-telescope-astrophysics https://www.nationalgeographic.com/science/article/first-pic...
slimginz 4y ago
That was the M87 black hole image that came out back in 2019 https://solarsystem.nasa.gov/resources/2319/first-image-of-a-black-hole/ https://solarsystem.nasa.gov/resources/2319/first-image-of-a...
josu 4y ago
Yeah, this image is quite old, around 27k years or so.

belter 4y ago

Announcement press conference: "Press conference on Milky Way galaxy discovery from the Event Horizon Telescope collaboration" https://youtu.be/KgvPA9RmEnk https://youtu.be/KgvPA9RmEnk

ramigb 4y ago

Can the smart people in here confirm if we are getting sucked into this someday or not?

hathym 4y ago
don't worry, we will destroy the planet before that.
jepler 4y ago
On the timescale from now until the sun goes nova, confident "no". Roughly speaking, the sun orbits the galactic center at a velocity of 220km/s. To fall into, or to be sucked into, the central black hole would require the loss of all this velocity, which means applying acceleration to the sun opposite the direction of its orbit. Lots of acceleration. That has to come from somewhere. I suppose there's some extremely tiny amount of drag that occurs due to the sun moving in the interstellar medium, but aside from that there's not a lot that applies acceleration to the sun opposite the direction of its orbit. Really the only other thing that comes to mind are the gravitational waves that are radiated by co-rotating objects. This is the effect that causes close by black holes to eventually come close enough that they merge. But in objects traveling at slower speeds in larger orbits, this effect is also negligible on the scale of billions of years. (These are the gravitational waves observed by LIGO). https://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity#Gravitational_radiation https://en.wikipedia.org/wiki/Two-body_problem_in_general_re...
- perardi 4y ago
  [pushes up glasses] The Sun is nowhere near massive enough to become supernova. https://en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaustion https://en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaus... It will become a red giant, and then eventually end up a white dwarf.
  - jepler 4y ago
    Thanks for the correction. You're right, current scientific thinking is that the sun is not capable of going "supernova".

coryfklein 4y ago

I'm sorry, I am really confused. Didn't we get "the first picture of the black hole at the center of our galaxy" like 2-3 years ago? I definitely remember seeing a nearly identical photo, and lots of press coverage about a particularly young woman who was closely involved in the project. What that something different?

black_puppydog 4y ago
as crazy as it sounds: that black hole was actually in a different galaxy :)
- infogulch 4y ago
  Funnily enough, M87* is bigger than Sgr A* by about the same factor than it is farther away (~2000x ?), and these effects mostly cancel out so the effective resolution of each is about the same. They chose to image M87* first because there is less dust/gas obstructing the view through intergalactic space to M87 than through the bulk of the milky way disk.
sgregnt 4y ago
The image from a few years ago, was taken of a blackhole in a different galaxy.
ritwikgupta 4y ago
That image was also captured by the EHT of the supermassive black hole (M87*) at the center of the M87 galaxy. The woman you're thinking of is Dr. Katie Bouman, now faculty at Caltech. She is also listed as an author on this work of imaging Sgr A*.
dseGH3FETWJJy 4y ago
Nope, that was a black hole in another galaxy- Messier 87
deleted 4y ago
[deleted]
4y ago

bholevid34 4y ago

Extremely cool video, "Meet Sgr A*: Zooming into the black hole at the centre of our galaxy": https://www.youtube.com/watch?v=Zml0dZCjaFw https://www.youtube.com/watch?v=Zml0dZCjaFw

muxneo 4y ago

Size of rings prove Einstein's Theory of relativity. This is an amazing work

Maursault 4y ago

Didn't we see this image last April? What is new here? tia

Apocryphon 4y ago

Funnily enough, Arcade Fire released a new album this week, which just happens to have a song entitled Sagittarius A* https://www.youtube.com/watch?v=rAUpD4FchZI https://www.youtube.com/watch?v=rAUpD4FchZI https://genius.com/25770411 https://genius.com/25770411

denton-scratch 4y ago

I am impressed. I have a few ignorant questions: 1. There are three bright blobs on the image; I assume they are the same object, behind the BH. What are they/is it? They said the image was averaged; so presumably whatever the blobs are wasn't moving? 2. Is it correct that the rest of the ring, ignoring the three blobs, is the far side of the accretion disk? Why can't I see this side of the accretion disk? 3. According to the article, at least one submillimeter telescope was important. But submillimeter is infrared, isn't it? I thought infrared was blocked by dust, and if there's one thing there's a lot of at the centre of the galaxy, it's dust? [Edit] Questions 1 and two were prompted by this remark in the article: "The new view captures light bent by the powerful gravity of the black hole" The only "light" I can see is a ring with blobs in it; that's why I suppose the ring in the image is not the accretion disk, at least, not as viewed from the pole. Most other commenters here assume (or know) that it is the accretion disk, and we are looking at a pole. But if that is indeed the accretion disk, then that isn't light that's been bent by the gravity of the black hole. Perhaps the explanation is that many other commenters haven't actually read the article, possibly because they already know the story.

kryptn 4y ago
> 3. According to the article, at least one submillimeter telescope was important. But submillimeter is infrared, isn't it? I thought infrared was blocked by dust, and if there's one thing there's a lot of at the centre of the galaxy, it's dust? It's the opposite actually! Infrared light is able to go through dust. > Another reason [to look at the universe in the infrared] is because stars and planets form in clouds of gas and dust, and this dust obscures our view. Infrared light penetrates these clouds and allows us to see inside. https://www.nasa.gov/content/goddard/webb-conversations-its-all-about-infrared-why-build-the-james-webb-space-telescope https://www.nasa.gov/content/goddard/webb-conversations-its-...
- denton-scratch 4y ago
  OK, that explains that; thanks.
whitesilhouette 4y ago

nyc111 4y ago

Matt Strassler: «The details of the reconstructed image depend on exactly what assumptions are made.» https://profmattstrassler.com/2022/05/12/in-our-galaxys-center-a-tiny-monster/ https://profmattstrassler.com/2022/05/12/in-our-galaxys-cent... What does this mean? If they assembled an image to fit their assumptions, that would be circular reasoning. I don't understand.

storedsun 4y ago

iliketrains 4y ago

This is incredible! Veritasium has a nice video explaining how those images were obtained and what they mean: https://www.youtube.com/watch?v=Q1bSDnuIPbo https://www.youtube.com/watch?v=Q1bSDnuIPbo

sidcool 4y ago

I still can't wrap my head around the fact that black holes are real things. And GR predicts them so accurately.

leommoore 4y ago

There is something cool about being able to see something so powerful in the far reaches of space as it looked 27,000 years ago.