5 ms·

Maybe Hubble could take a snapshot or two?

by wrycoder 5y ago

frosted-flakes 5y ago
With Hubbles's highest resolution optics, the JWST will be about one-tenth the size of a pixel.
- ddingus 5y ago
  Scale. We are just a bit of noise in an impossible to understand large, complex system. It is crazy to think about.
- idealmedtech 5y ago
  How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!
  - dheerendra73 5y ago
    Well galaxies at billions of light years distance are also 100000s light years wide. Rest of the math you can do about resolution now!
  - heavenlyblue 5y ago
    It’s interesting that you are expressing an opinion about something that you could calculate in the same amount of time it took to write down that opinion.
    - weaksauce 5y ago
      It seems like they are going for the "the easiest way to get a right answer is give the wrong answer on the internet" approach.
      - Spare_account 5y ago
        Cunningham's Law https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham's_Law%22 https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
    - Sebb767 5y ago
      To be fair, for someone who is not well-versed in either optics or space physics, calculating the answer is not that straight-forward.
      - kadoban 5y ago
        You can do pretty well just comparing the ratios of the size to the distance, right? Or is it more than that?
        idealmedtech 5y ago
        That's a start, for sure, but to do a super accurate calculation (the kind I feel unqualified to carry out), you need to take into account apparent size, redshift, whether or not there's gravitational lensing, interstellar dust in the way, etc etc. But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.
    - idealmedtech 5y ago
      It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows: 1) how absolutely mindblowingly big space is 2) how bad humans really are at intuiting things at the scale of space
  - Spare_account 5y ago
    >a truck sized craft at a few million light years? JWST is three light seconds from earth
    - idealmedtech 5y ago
      Awful typo on my part! Definitely face palmed when I caught it.
  - frosted-flakes 5y ago
    Here's the math[1]. Seems believable to me. The Web telescope is miniscule conpared to faraway galaxies, and it doesn't emit much light. [1]: https://mobile.twitter.com/gfish/status/1479339620785524736 https://mobile.twitter.com/gfish/status/1479339620785524736
    - idealmedtech 5y ago
      I did a little math of my own, and found that while the ratio of these distances is on the order of 10^15, the ratio of the sizes of these objects is on the order of 10^19. In other words, Webb is only one TEN THOUSANDTH the apparent size of a galaxy that's a _billion light years away_ That's just mind numbing to consider!
  - jibalt 5y ago
    galaxy_width / truck_width = 3 × 10^20
- xvector 5y ago
  That is staggering. Just, wow.
  - nullc 5y ago
    Hubble can't see the Apollo descent stage on the moon either, and that is a LOT closer than L2.
delecti 5y ago
TLDR: Not really. At the distance of the JWST, a single pixel on the hubble's camera is about 700m across, or roughly 30 times the size of the JWST. The L2 point is about 1.5 million km from earth [0]. The smallest size Hubble can resolve is about 1/20 arcsecond [1]. It's in a pretty low orbit, so is effectively "on earth" relative to the distance to the L2 point where JWST is. Calculating the size of an angular measure at a given distance [2], you get about 727m [3]. [0] https://en.wikipedia.org/wiki/Lagrange_point#L2_point https://en.wikipedia.org/wiki/Lagrange_point#L2_point [1] https://illuminateduniverse.org/2019/04/11/angular-resolution-and-what-hubble-cant-see/ https://illuminateduniverse.org/2019/04/11/angular-resolutio... [2] https://astronomy.stackexchange.com/a/20728 https://astronomy.stackexchange.com/a/20728 [3] https://www.wolframalpha.com/input/?i=tan%28%281+arcsec%29%2F20%29+*+1.5+million+km https://www.wolframalpha.com/input/?i=tan%28%281+arcsec%29%2...

Maybe Hubble could take a snapshot or two?

frosted-flakes 5y ago

With Hubbles's highest resolution optics, the JWST will be about one-tenth the size of a pixel.

ddingus 5y ago
Scale. We are just a bit of noise in an impossible to understand large, complex system. It is crazy to think about.
idealmedtech 5y ago
How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!
- dheerendra73 5y ago
  Well galaxies at billions of light years distance are also 100000s light years wide. Rest of the math you can do about resolution now!
- heavenlyblue 5y ago
  It’s interesting that you are expressing an opinion about something that you could calculate in the same amount of time it took to write down that opinion.
  - weaksauce 5y ago
    It seems like they are going for the "the easiest way to get a right answer is give the wrong answer on the internet" approach.
    - Spare_account 5y ago
      Cunningham's Law https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham's_Law%22 https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
  - Sebb767 5y ago
    To be fair, for someone who is not well-versed in either optics or space physics, calculating the answer is not that straight-forward.
    - kadoban 5y ago
      You can do pretty well just comparing the ratios of the size to the distance, right? Or is it more than that?
      - idealmedtech 5y ago
        That's a start, for sure, but to do a super accurate calculation (the kind I feel unqualified to carry out), you need to take into account apparent size, redshift, whether or not there's gravitational lensing, interstellar dust in the way, etc etc. But I want to reiterate that what's meaningful about this discussion is in part how unintuitive things at the far edges of our scales of perception really are. It's a muscle that, left untrained, will lead you to make incorrect characterizations like the one I made.
  - idealmedtech 5y ago
    It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows: 1) how absolutely mindblowingly big space is 2) how bad humans really are at intuiting things at the scale of space
- Spare_account 5y ago
  >a truck sized craft at a few million light years? JWST is three light seconds from earth
  - idealmedtech 5y ago
    Awful typo on my part! Definitely face palmed when I caught it.
- frosted-flakes 5y ago
  Here's the math[1]. Seems believable to me. The Web telescope is miniscule conpared to faraway galaxies, and it doesn't emit much light. [1]: https://mobile.twitter.com/gfish/status/1479339620785524736 https://mobile.twitter.com/gfish/status/1479339620785524736
  - idealmedtech 5y ago
    I did a little math of my own, and found that while the ratio of these distances is on the order of 10^15, the ratio of the sizes of these objects is on the order of 10^19. In other words, Webb is only one TEN THOUSANDTH the apparent size of a galaxy that's a _billion light years away_ That's just mind numbing to consider!
- jibalt 5y ago
  galaxy_width / truck_width = 3 × 10^20
xvector 5y ago
That is staggering. Just, wow.
- nullc 5y ago
  Hubble can't see the Apollo descent stage on the moon either, and that is a LOT closer than L2.

delecti 5y ago

TLDR: Not really. At the distance of the JWST, a single pixel on the hubble's camera is about 700m across, or roughly 30 times the size of the JWST. The L2 point is about 1.5 million km from earth [0]. The smallest size Hubble can resolve is about 1/20 arcsecond [1]. It's in a pretty low orbit, so is effectively "on earth" relative to the distance to the L2 point where JWST is. Calculating the size of an angular measure at a given distance [2], you get about 727m [3]. [0] https://en.wikipedia.org/wiki/Lagrange_point#L2_point https://en.wikipedia.org/wiki/Lagrange_point#L2_point [1] https://illuminateduniverse.org/2019/04/11/angular-resolution-and-what-hubble-cant-see/ https://illuminateduniverse.org/2019/04/11/angular-resolutio... [2] https://astronomy.stackexchange.com/a/20728 https://astronomy.stackexchange.com/a/20728 [3] https://www.wolframalpha.com/input/?i=tan%28%281+arcsec%29%2F20%29+*+1.5+million+km https://www.wolframalpha.com/input/?i=tan%28%281+arcsec%29%2...