7 ms·

Sky-scanning complete for Gaia

177 points by sohkamyung 2y ago

qwertox 2y ago
You may want to know: the high-res images which are offered for downloading contain the same image which is shown on the page, that is, the infographic. Not worth the download, as I thought that it would contain a huge panorama of the sky.
- robin_reala 2y ago
  The downlinked data is claimed to be 142TB compressed. I suspect that the huge panorama might be a little big for your computer.
- IndrekR 2y ago
  For real data you can use Gaia ESA archive: https://gea.esac.esa.int/archive/ https://gea.esac.esa.int/archive/ I went to study MSc in Space Science and Technology as a hobby few years ago. In one course (2022) we had an assignment to find Supernovae from recent Gaia data (Python code). Then made sure this is observable by University’s robotic telescope (and compliant with local weather forecast). Next requested the observation from the telescope and if successful, received the pictures next day. Had to analyse the results as well. It surprised me how much data there actually is available in quite open format from ESA missions. Controlling remote telescope few thousand kilometres away was also a nice experience.
  - thisguy47 2y ago
    Which university if you don't mind me asking? I'm interested in doing something similar as a hobby.
    - IndrekR 2y ago
      The Open University in UK (living in Estonia myself): https://www.open.ac.uk/postgraduate/qualifications/f77 https://www.open.ac.uk/postgraduate/qualifications/f77 The course was S818.
boxed 2y ago
I wonder if it could keep giving us useful data without the precision rotation? Intuitively it seems like we should be able to figure out where it's pointing by star-matching plus dead reckoning based on the last frame.
- ndileas 2y ago
  It's possible...but the point of this instrument is to measure star locations very precisely. It probably has a star tracker for positioning doing what you're suggesting. If you were to use that type of positioning info you could introduce inaccuracies into the measured data eventually. Also, every mission comes to an end eventually - better to do it in the right way and have the right amount of propellent saved for either a graveyard orbit or de-orbiting. It met the mission timeline and goals.
  - boxed 2y ago
    Yea ok. Still, it seems like it could produce a lot of very useful data if switched to a blind spinning mode.
- gmiller123456 2y ago
  The current coordinate system is based on extremely distant radio sources. Ground based scopes found some bright galactic sources which GAIA aligned to, and is measuring everything relative to those. And now GAIA is the defining source of the ICRS for optical observations.
- jcrawfordor 2y ago
  when you're trying to take relative measurements of the motion of objects within the field of view, which is how you do these fine position measurements, you don't have a lot of choices for objects with a measured location accuracy similar to the measurements you're taking. You're measuring the precise position of something compared to other things you don't know the precise position of. That requires a very stable platform so you can do comparisons internally. There are lots of options for precisely determining where you're pointing but pretty much all of them involve a loss of precision whenever the platform moves, so if you have to slew to a guidestar and back your accuracy is limited to the measurement of the guidestar and then the error induced when you slewed. You also end up using different instruments for alignment measurements vs. the actual observation (for example because the observation requires a long time at a static position), and there's an imprecision involved in comparing the different instruments because they slightly move relative to each other with thermal effects and so on. When you really get into it, using some instruments will reduce the precision of other instruments because they vibrate the platform or create heat. You have to account for all of this with a complex model. In practice these highly precise measurements, at least in the domain I'm familiar with, become sensor fusion problems where you take a lot of sources of position info, weight them based on their accuracy, and integrate them over time. The less stable the platform, the more error is induced by the integrating over time. Nothing in that realm is really all-or-nothing, as we're seeing with Hubble as it racks up more and more failures, but the loss of the rotation will mean more error in combining position references which will mean less accurate final observations. They may no longer be that much more accurate than measurements obtained by other means. I'm not sure if I explained that very coherently, it's a complex field that I used to write software in but, well, I was the person writing the software, not the person figuring out the theory. The general idea is that space-based instruments tend to have a bunch of different factors that go into their final accuracy and that accuracy normally gets worse over time as you run out of fuel and things degrade and ultimately stop functioning. Fortunately since space-based systems cost so much to build and launch, the teams behind them have usually put a lot of thought into how they'll continue to get the best use out of them as they get older. That often means having future plans for different missions that just don't require as much accuracy, which is the case with Gaia---it's ending this "phase" of the mission plan.
NKosmatos 2y ago
Direct link to some very very nice images and animations: https://www.esa.int/Science_Exploration/Space_Science/Gaia https://www.esa.int/Science_Exploration/Space_Science/Gaia Two of my favorites: https://www.esa.int/ESA_Multimedia/Images/2025/The_best_Milky_Way_map_by_Gaia https://www.esa.int/ESA_Multimedia/Images/2025/The_best_Milk... https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_Milky_Way_map_by_Gaia_edge-on https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_M...
- dylan604 2y ago
  I get how Gaia could make the best edge on image, but how could Gaia (or anything man made) get the the "best" face on image?
  - iAmAPencilYo 2y ago
    All of these are "Artist's Impressions". My best guess is they run a simulation based on the data from the spacecraft and then can pan the camera around as they see fit
    - BizarroLand 2y ago
      From the page: [Image Description: A model image of what our home galaxy, the Milky Way, might look like edge-on, against a pitch-black backdrop. The Milky Way’s disc appears in the centre of the image, as a thin, dark-brown line spanning from left to right, with the hint of a wave in it. The line appears to be etched into a thin glowing layer of silver sand, that makes it look as if it was drawn with a coloured pencil on coarse paper. The bulge of the galaxy sits like a glowing, see-through pearl in the shape of a sphere in the centre of this brown line.]
      - hahajk 2y ago
        That's an AI produced accessibility description so I thought it seemed wrong. But more directly from the article text: This is a new artist’s impression of our galaxy, the Milky Way, based on data from ESA’s Gaia space telescope.
tokai 2y ago
And now to use the data to make the most realistic scifi game. With correct stellar motion during relativistic travel.
- flohofwoe 2y ago
  Elite Dangerous already has more known star systems (160k) in the Milky Way than you can realistically visit - and the rest (400 billion) filled in with plausibly simulated systems: https://elite-dangerous.fandom.com/wiki/Galaxy#Milky_Way https://elite-dangerous.fandom.com/wiki/Galaxy#Milky_Way - it even kind-of predicted a star system that was only discovered after the game was released: https://elite-dangerous.fandom.com/wiki/Trappist-1#Impact_of_Discovery_on_Elite_Dangerous https://elite-dangerous.fandom.com/wiki/Trappist-1#Impact_of...
  - buildbot 2y ago
    I didn’t realize a game actually used an approach like this, really cool. Reminds me of the simulated MMORG world in Neal Stephenson’s README, where they tried to simulate the formation of the planet to get realistic mineral deposits and topology.
    - vimax 2y ago
      REAMDE
      - buildbot 2y ago
        Oops, thanks!
      - NetOpWibby 2y ago
        I just looked this up, sounds like a fantastic read. I'll add it to my backlog.
    - Cthulhu_ 2y ago
      Thing is, they can make a predictive model based on known observations, then on this scale they will get it right or right enough plenty of times. I'm here for it. I hope long term (VERY long term) humanity will go to these stars predicted by Elite and name planets after the players that first discovered them, lol.
PittleyDunkin 2y ago
I really wish they would have identified Gaia as some kind of satellite. Gaia is also a name for Earth itself.
marcodiego 2y ago
IIRC Gaia had a performance degradation because of stray light, probably ice on the border of it's aperture[1]. How has that affected this result? [1] https://blogs.esa.int/gaia/2014/06/16/preliminary-analysis-of-stray-light-impact-and-strategies/ https://blogs.esa.int/gaia/2014/06/16/preliminary-analysis-o...
- sega_sai 2y ago
  It was not ice, but fibers from the sun shield. The ice issue was resolved by heating the satellite. The stray light issue affected spectra measurements, but not the astrometric side of the mission
ndileas1 2y ago
Now that most stars are mapped, next step: map all the planets.
mrbluecoat 2y ago
Farewell, friend. Hello, LSST.
lysace 2y ago
Gaia has a 1.0 × 0.5 m focal plane array on which light from both telescopes is projected. This in turn consists of 106 CCDs of 4500 × 1966 pixels each, for a total of 937.8 megapixels. Neat.
- perihelions 2y ago
  The really neat part is the instrument precision. It's terrifyingly good and I have no idea how it (really) works. - "Gaia measures their positions to an accuracy of 24 microarcseconds, comparable to measuring the diameter of a human hair at a distance of 1000 km" https://www.esa.int/Science_Exploration/Space_Science/Gaia/Cosmic_distances https://www.esa.int/Science_Exploration/Space_Science/Gaia/C...
  - colechristensen 2y ago
    Isn't that just the distance between pixels and the image projected onto them?
    - perihelions 2y ago
      No: it's far weirder and I'm not knowledgeable enough to explain it.
    - echoangle 2y ago
      Probably not. The accuracy with which you know the pointing of the telescope probably also plays into it (unless the FOV is large enough to have other stars as a reference?), and you can do subpixel positioning of objects to get more accuracy than full pixel steps.
  - yshklarov 2y ago
    To nitpick with the grammar in the quote: It's capable of measuring to the accuracy of 120 μm at 1000 km. So it cannot accurately measure the diameter of a human hair (which ranges from around 20 to 200 μm) at that distance, but only to the accuracy of a human hair.
Qem 2y ago
Hope they have captured an image of Planet Nine somewhere there, and eventually are able to pinpoint it.
- spartanatreyu 2y ago
  I don't think it would have a detection. Gaia is a a satellite for mapping star positions and any possible planets past Neptune would be very faint. It's also not a telescope in the traditional sense, it's more like a bar scanner in a supermarket but it's spinning around.
- Cthulhu_ 2y ago
  I'm really curious whether it exists and / or if they will ever be able to find it, it's wild to consider they can map the galaxy but can't spot something that's relatively close to us. But, detection relies on reflected sunlight or blotting out stars etc behind it, and given the supposed distance that would be minimal. That said, if it does exist I'm sure they'll find it eventually.
guenthert 2y ago
Uh-huh, just in time it seems. "Gaia’s fuel tank is now approaching empty" Well, congrats to all involved to such a supremely successful and important mission. When I went to school, it was said that astronomers were happy if they get the order of a measurement right. No such excuses anymore (at least for some 2 billion "nearby" objects)!
laacz 2y ago
Has anyone created a 3D map, available via web and with ability to fly through, jump to stellar objects by name, look around, etc?

177 points by sohkamyung 2y ago

You may want to know: the high-res images which are offered for downloading contain the same image which is shown on the page, that is, the infographic. Not worth the download, as I thought that it would contain a huge panorama of the sky.

robin_reala 2y ago
The downlinked data is claimed to be 142TB compressed. I suspect that the huge panorama might be a little big for your computer.
IndrekR 2y ago
For real data you can use Gaia ESA archive: https://gea.esac.esa.int/archive/ https://gea.esac.esa.int/archive/ I went to study MSc in Space Science and Technology as a hobby few years ago. In one course (2022) we had an assignment to find Supernovae from recent Gaia data (Python code). Then made sure this is observable by University’s robotic telescope (and compliant with local weather forecast). Next requested the observation from the telescope and if successful, received the pictures next day. Had to analyse the results as well. It surprised me how much data there actually is available in quite open format from ESA missions. Controlling remote telescope few thousand kilometres away was also a nice experience.
- thisguy47 2y ago
  Which university if you don't mind me asking? I'm interested in doing something similar as a hobby.
  - IndrekR 2y ago
    The Open University in UK (living in Estonia myself): https://www.open.ac.uk/postgraduate/qualifications/f77 https://www.open.ac.uk/postgraduate/qualifications/f77 The course was S818.

boxed 2y ago

I wonder if it could keep giving us useful data without the precision rotation? Intuitively it seems like we should be able to figure out where it's pointing by star-matching plus dead reckoning based on the last frame.

ndileas 2y ago
It's possible...but the point of this instrument is to measure star locations very precisely. It probably has a star tracker for positioning doing what you're suggesting. If you were to use that type of positioning info you could introduce inaccuracies into the measured data eventually. Also, every mission comes to an end eventually - better to do it in the right way and have the right amount of propellent saved for either a graveyard orbit or de-orbiting. It met the mission timeline and goals.
- boxed 2y ago
  Yea ok. Still, it seems like it could produce a lot of very useful data if switched to a blind spinning mode.
gmiller123456 2y ago
The current coordinate system is based on extremely distant radio sources. Ground based scopes found some bright galactic sources which GAIA aligned to, and is measuring everything relative to those. And now GAIA is the defining source of the ICRS for optical observations.
jcrawfordor 2y ago
when you're trying to take relative measurements of the motion of objects within the field of view, which is how you do these fine position measurements, you don't have a lot of choices for objects with a measured location accuracy similar to the measurements you're taking. You're measuring the precise position of something compared to other things you don't know the precise position of. That requires a very stable platform so you can do comparisons internally. There are lots of options for precisely determining where you're pointing but pretty much all of them involve a loss of precision whenever the platform moves, so if you have to slew to a guidestar and back your accuracy is limited to the measurement of the guidestar and then the error induced when you slewed. You also end up using different instruments for alignment measurements vs. the actual observation (for example because the observation requires a long time at a static position), and there's an imprecision involved in comparing the different instruments because they slightly move relative to each other with thermal effects and so on. When you really get into it, using some instruments will reduce the precision of other instruments because they vibrate the platform or create heat. You have to account for all of this with a complex model. In practice these highly precise measurements, at least in the domain I'm familiar with, become sensor fusion problems where you take a lot of sources of position info, weight them based on their accuracy, and integrate them over time. The less stable the platform, the more error is induced by the integrating over time. Nothing in that realm is really all-or-nothing, as we're seeing with Hubble as it racks up more and more failures, but the loss of the rotation will mean more error in combining position references which will mean less accurate final observations. They may no longer be that much more accurate than measurements obtained by other means. I'm not sure if I explained that very coherently, it's a complex field that I used to write software in but, well, I was the person writing the software, not the person figuring out the theory. The general idea is that space-based instruments tend to have a bunch of different factors that go into their final accuracy and that accuracy normally gets worse over time as you run out of fuel and things degrade and ultimately stop functioning. Fortunately since space-based systems cost so much to build and launch, the teams behind them have usually put a lot of thought into how they'll continue to get the best use out of them as they get older. That often means having future plans for different missions that just don't require as much accuracy, which is the case with Gaia---it's ending this "phase" of the mission plan.

NKosmatos 2y ago

Direct link to some very very nice images and animations: https://www.esa.int/Science_Exploration/Space_Science/Gaia https://www.esa.int/Science_Exploration/Space_Science/Gaia Two of my favorites: https://www.esa.int/ESA_Multimedia/Images/2025/The_best_Milky_Way_map_by_Gaia https://www.esa.int/ESA_Multimedia/Images/2025/The_best_Milk... https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_Milky_Way_map_by_Gaia_edge-on https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_M...

dylan604 2y ago
I get how Gaia could make the best edge on image, but how could Gaia (or anything man made) get the the "best" face on image?
- iAmAPencilYo 2y ago
  All of these are "Artist's Impressions". My best guess is they run a simulation based on the data from the spacecraft and then can pan the camera around as they see fit
  - BizarroLand 2y ago
    From the page: [Image Description: A model image of what our home galaxy, the Milky Way, might look like edge-on, against a pitch-black backdrop. The Milky Way’s disc appears in the centre of the image, as a thin, dark-brown line spanning from left to right, with the hint of a wave in it. The line appears to be etched into a thin glowing layer of silver sand, that makes it look as if it was drawn with a coloured pencil on coarse paper. The bulge of the galaxy sits like a glowing, see-through pearl in the shape of a sphere in the centre of this brown line.]
    - hahajk 2y ago
      That's an AI produced accessibility description so I thought it seemed wrong. But more directly from the article text: This is a new artist’s impression of our galaxy, the Milky Way, based on data from ESA’s Gaia space telescope.

tokai 2y ago

And now to use the data to make the most realistic scifi game. With correct stellar motion during relativistic travel.

flohofwoe 2y ago
Elite Dangerous already has more known star systems (160k) in the Milky Way than you can realistically visit - and the rest (400 billion) filled in with plausibly simulated systems: https://elite-dangerous.fandom.com/wiki/Galaxy#Milky_Way https://elite-dangerous.fandom.com/wiki/Galaxy#Milky_Way - it even kind-of predicted a star system that was only discovered after the game was released: https://elite-dangerous.fandom.com/wiki/Trappist-1#Impact_of_Discovery_on_Elite_Dangerous https://elite-dangerous.fandom.com/wiki/Trappist-1#Impact_of...
- buildbot 2y ago
  I didn’t realize a game actually used an approach like this, really cool. Reminds me of the simulated MMORG world in Neal Stephenson’s README, where they tried to simulate the formation of the planet to get realistic mineral deposits and topology.
  - vimax 2y ago
    REAMDE
    - buildbot 2y ago
      Oops, thanks!
    - NetOpWibby 2y ago
      I just looked this up, sounds like a fantastic read. I'll add it to my backlog.
  - Cthulhu_ 2y ago
    Thing is, they can make a predictive model based on known observations, then on this scale they will get it right or right enough plenty of times. I'm here for it. I hope long term (VERY long term) humanity will go to these stars predicted by Elite and name planets after the players that first discovered them, lol.

PittleyDunkin 2y ago

I really wish they would have identified Gaia as some kind of satellite. Gaia is also a name for Earth itself.

marcodiego 2y ago

IIRC Gaia had a performance degradation because of stray light, probably ice on the border of it's aperture[1]. How has that affected this result? [1] https://blogs.esa.int/gaia/2014/06/16/preliminary-analysis-of-stray-light-impact-and-strategies/ https://blogs.esa.int/gaia/2014/06/16/preliminary-analysis-o...

sega_sai 2y ago
It was not ice, but fibers from the sun shield. The ice issue was resolved by heating the satellite. The stray light issue affected spectra measurements, but not the astrometric side of the mission

ndileas1 2y ago

Now that most stars are mapped, next step: map all the planets.

mrbluecoat 2y ago

Farewell, friend. Hello, LSST.

lysace 2y ago

Gaia has a 1.0 × 0.5 m focal plane array on which light from both telescopes is projected. This in turn consists of 106 CCDs of 4500 × 1966 pixels each, for a total of 937.8 megapixels. Neat.

perihelions 2y ago
The really neat part is the instrument precision. It's terrifyingly good and I have no idea how it (really) works. - "Gaia measures their positions to an accuracy of 24 microarcseconds, comparable to measuring the diameter of a human hair at a distance of 1000 km" https://www.esa.int/Science_Exploration/Space_Science/Gaia/Cosmic_distances https://www.esa.int/Science_Exploration/Space_Science/Gaia/C...
- colechristensen 2y ago
  Isn't that just the distance between pixels and the image projected onto them?
  - perihelions 2y ago
    No: it's far weirder and I'm not knowledgeable enough to explain it.
  - echoangle 2y ago
    Probably not. The accuracy with which you know the pointing of the telescope probably also plays into it (unless the FOV is large enough to have other stars as a reference?), and you can do subpixel positioning of objects to get more accuracy than full pixel steps.
- yshklarov 2y ago
  To nitpick with the grammar in the quote: It's capable of measuring to the accuracy of 120 μm at 1000 km. So it cannot accurately measure the diameter of a human hair (which ranges from around 20 to 200 μm) at that distance, but only to the accuracy of a human hair.

Qem 2y ago

Hope they have captured an image of Planet Nine somewhere there, and eventually are able to pinpoint it.

spartanatreyu 2y ago
I don't think it would have a detection. Gaia is a a satellite for mapping star positions and any possible planets past Neptune would be very faint. It's also not a telescope in the traditional sense, it's more like a bar scanner in a supermarket but it's spinning around.
Cthulhu_ 2y ago
I'm really curious whether it exists and / or if they will ever be able to find it, it's wild to consider they can map the galaxy but can't spot something that's relatively close to us. But, detection relies on reflected sunlight or blotting out stars etc behind it, and given the supposed distance that would be minimal. That said, if it does exist I'm sure they'll find it eventually.

guenthert 2y ago

Uh-huh, just in time it seems. "Gaia’s fuel tank is now approaching empty" Well, congrats to all involved to such a supremely successful and important mission. When I went to school, it was said that astronomers were happy if they get the order of a measurement right. No such excuses anymore (at least for some 2 billion "nearby" objects)!

laacz 2y ago

Has anyone created a 3D map, available via web and with ability to fly through, jump to stellar objects by name, look around, etc?