6 ms·

I'd be curious to know what it would take in terms of telescope size to directly image a nearby exoplanet.

tombh 4y ago
I actually came across this video on HN a while back: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI It explains the extraordinary idea of using the sun as a gravitational lens.
spartanatreyu 4y ago
You might be interested in this video which talks about using the Earth's gravity to create a telescope with a lens roughly the size of the Earth (a terrascope): https://www.youtube.com/watch?v=jgOTZe07eHA https://www.youtube.com/watch?v=jgOTZe07eHA They also have a follow up video about using Jupiter to create a jovoscope and there's also more about creating a telescope using the sun (although since the sensor would need to be so far away from the Sun, we would essentially need to launch a different spaceship for each target that we tried to image).
- meindnoch 4y ago
  >Earth's gravity *Earth’s atmosphere
  - mbrubeck 4y ago
    This got downvoted but it is correct. The "terrascope" concept depends on atmospheric rather than gravitational lensing. The deflection through the Earth's atmosphere is about 1 degree, which is orders of magnitude more than you get from the Earth's gravity. Using Earth as a gravitational lens would give you a focal point about 15000 AU (a quarter of a light year) away, far outside the solar system. But with atmospheric diffraction, you can get a focal point within the Earth–Moon system.
    - gateroid 4y ago
      I’m assuming the lazy downvoters had watched the recent PBS SpaceTime episode that talked about the gravitational lens approach in the context of exoplanet imaging, and just assumed that anything involving earth for lensing was gravity based.
- Etheryte 4y ago
  Cool topic, but completely unacceptable to rant 20 minutes on tangentially related topics before getting to the actual issue at hand. I understand that Youtube prefers longer videos for monetization, but this is absurd.
  - lupire 4y ago
    This is the most entitled comment I've seen all week. The video has a clickable chapter list and a time scrubber, and the other chapters are closely related.
    - gizmodo59 4y ago
      That still doesn’t disprove the point though. I like videos that get straight to the topic of the title rather than blabbering. It’s very frustrating to see deceiving titles and the actual content related to the title is 2% of the entire video..
      - aylmao 4y ago
        IMHO, the title is not deceiving. As of right now it's "Turning Earth Into a Telescope", and he talks about just this from a historic standpoint. If you were hoping for the technicalities of it, then I can see how it's not what you want. I know what I think is enough about the history of telescopes, so I skipped that part, but I thought the history behind how he came up with the idea fits squarely into the title.
        kortilla 4y ago
        “Guide to replacing a toilet float valve” doesn’t need to include the history of plumbing.
        aylmao 4y ago
        I sure look forward to watching "Guide to turn Earth Into a Telescope". I'd expect it to be be a different video.
- thaumasiotes 4y ago
  > They also have a follow up video about using Jupiter to create a jovoscope Just for fun, if you wanted to form the word from Greek roots instead of mixing Latin into it, it'd be "dioscope". If you stick with the Latin, it's ambiguous whether the combining vowel should be -i-, agreeing with the Latin root ("joviscope") or -o-, agreeing with the Greek root ("jovoscope"). (And for completeness, if you wanted to do it entirely in Latin, the word would probably be "jovivide", but it is generally Not Done to form verbal compounds like that in Latin, unless the verb you're using is either ferre or gerere [both meaning "carry"].)
  - adrian_b 4y ago
    Entirely in Latin, "videre" would not be the right corespondent verb for "scope" (from Greek "skopos"), but "spectare" (source of English "spectator"), so one could say in Latin "jovispectum" in the neuter gender (something that looks at Jupiter) or "jovispectus" in the masculine gender, though the latter would be more appropriate for the human who uses the instrument, not for the instrument. An example of a real Latin word formed in the same way is "circumspectus" (someone who looks around) => English "circumspect", so one could say in English "jovispect". Word compounds from a noun stem with the last vowel changed to "i" + a verbal stem + the thematic vowel, in either the masculine or the feminine gender, are numerous in Latin and formed from many verbs, not only from "ferre" and "gerere". For example there are many animal names, e.g. sanguisuga (blood-sucker = leech), caprimulgus (goat-milker = nightjar), ossifraga (bone-breaker = bearded vulture), vipera (alive-baby-birth-giver = viper) and others. There are also some insulting names formed in this way in Latin, but those are NSFW, so you may try to guess them, as they also correspond in English to the pattern *-*er, like "blood-sucker".
    - thaumasiotes 4y ago
      > vipera (alive-baby-birth-giver = viper) This one seems like a stretch? I'm also curious why you interpret the formation as "noun stem with final vowel changed to i", as opposed to "noun stem followed by epenthetic i".
      - 4y ago
- devoutsalsa 4y ago
  That’s a rookie telescope. Let’s use the sun! https://youtu.be/4d0EGIt1SPc https://youtu.be/4d0EGIt1SPc
krono 4y ago
There are actual (conceptual :D) plans by NASA to use our own sun as a gravitational lens to achieve just that. The concept is by Slava Turyshev and titled "Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravitational Lens Mission". I'm only a casualstronomer and don't consider myself qualified to provide further details. Should be easy enough to find though!
- andyjohnson0 4y ago
  Link: https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_I_Phase_II/Direct_Multipixel_Imaging_and_Spectroscopy_of_an_Exoplanet/ https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
comboy 4y ago
Sun size. https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc
- contravariant 4y ago
  As in one solar mass of telescope or just a telescope as wide as the sun's radius? The latter seems achievable, if tricky.
  - lasc4r 4y ago
    It uses the sun's gravity as a gravitational lens. You fly a normal sized telescope to the focal point. The theoretical resolution is pretty mindblowing, we'd be able to make out oceans and continents on exoplanets.
    - andyjohnson0 4y ago
      The main problem seems to be getting to the focal point, which is 500+ AUs from the Earth.
colechristensen 4y ago
JWST follow up in planning stages named for Carl Sagan is considerably bigger, optical, and being designed to be able to directly image exoplanets. https://youtu.be/BIgQpXObjFI https://youtu.be/BIgQpXObjFI
dakr 4y ago
Well, you can do it with an 8m-diameter primary mirror, because it's been done at Gemini Observatory. Keck and the VLT have directly imaged exoplanets as well. See this list: https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...
- eesmith 4y ago
  I suspect greesil means resolved beyond a point source. We've so far only managed that for stars: https://en.wikipedia.org/wiki/List_of_stars_with_resolved_images https://en.wikipedia.org/wiki/List_of_stars_with_resolved_im... .
prox 4y ago
Already done! https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...

I actually came across this video on HN a while back: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI It explains the extraordinary idea of using the sun as a gravitational lens.

spartanatreyu 4y ago

You might be interested in this video which talks about using the Earth's gravity to create a telescope with a lens roughly the size of the Earth (a terrascope): https://www.youtube.com/watch?v=jgOTZe07eHA https://www.youtube.com/watch?v=jgOTZe07eHA They also have a follow up video about using Jupiter to create a jovoscope and there's also more about creating a telescope using the sun (although since the sensor would need to be so far away from the Sun, we would essentially need to launch a different spaceship for each target that we tried to image).

meindnoch 4y ago
>Earth's gravity *Earth’s atmosphere
- mbrubeck 4y ago
  This got downvoted but it is correct. The "terrascope" concept depends on atmospheric rather than gravitational lensing. The deflection through the Earth's atmosphere is about 1 degree, which is orders of magnitude more than you get from the Earth's gravity. Using Earth as a gravitational lens would give you a focal point about 15000 AU (a quarter of a light year) away, far outside the solar system. But with atmospheric diffraction, you can get a focal point within the Earth–Moon system.
  - gateroid 4y ago
    I’m assuming the lazy downvoters had watched the recent PBS SpaceTime episode that talked about the gravitational lens approach in the context of exoplanet imaging, and just assumed that anything involving earth for lensing was gravity based.
Etheryte 4y ago
Cool topic, but completely unacceptable to rant 20 minutes on tangentially related topics before getting to the actual issue at hand. I understand that Youtube prefers longer videos for monetization, but this is absurd.
- lupire 4y ago
  This is the most entitled comment I've seen all week. The video has a clickable chapter list and a time scrubber, and the other chapters are closely related.
  - gizmodo59 4y ago
    That still doesn’t disprove the point though. I like videos that get straight to the topic of the title rather than blabbering. It’s very frustrating to see deceiving titles and the actual content related to the title is 2% of the entire video..
    - aylmao 4y ago
      IMHO, the title is not deceiving. As of right now it's "Turning Earth Into a Telescope", and he talks about just this from a historic standpoint. If you were hoping for the technicalities of it, then I can see how it's not what you want. I know what I think is enough about the history of telescopes, so I skipped that part, but I thought the history behind how he came up with the idea fits squarely into the title.
      - kortilla 4y ago
        “Guide to replacing a toilet float valve” doesn’t need to include the history of plumbing.
        aylmao 4y ago
        I sure look forward to watching "Guide to turn Earth Into a Telescope". I'd expect it to be be a different video.
thaumasiotes 4y ago
> They also have a follow up video about using Jupiter to create a jovoscope Just for fun, if you wanted to form the word from Greek roots instead of mixing Latin into it, it'd be "dioscope". If you stick with the Latin, it's ambiguous whether the combining vowel should be -i-, agreeing with the Latin root ("joviscope") or -o-, agreeing with the Greek root ("jovoscope"). (And for completeness, if you wanted to do it entirely in Latin, the word would probably be "jovivide", but it is generally Not Done to form verbal compounds like that in Latin, unless the verb you're using is either ferre or gerere [both meaning "carry"].)
- adrian_b 4y ago
  Entirely in Latin, "videre" would not be the right corespondent verb for "scope" (from Greek "skopos"), but "spectare" (source of English "spectator"), so one could say in Latin "jovispectum" in the neuter gender (something that looks at Jupiter) or "jovispectus" in the masculine gender, though the latter would be more appropriate for the human who uses the instrument, not for the instrument. An example of a real Latin word formed in the same way is "circumspectus" (someone who looks around) => English "circumspect", so one could say in English "jovispect". Word compounds from a noun stem with the last vowel changed to "i" + a verbal stem + the thematic vowel, in either the masculine or the feminine gender, are numerous in Latin and formed from many verbs, not only from "ferre" and "gerere". For example there are many animal names, e.g. sanguisuga (blood-sucker = leech), caprimulgus (goat-milker = nightjar), ossifraga (bone-breaker = bearded vulture), vipera (alive-baby-birth-giver = viper) and others. There are also some insulting names formed in this way in Latin, but those are NSFW, so you may try to guess them, as they also correspond in English to the pattern *-*er, like "blood-sucker".
  - thaumasiotes 4y ago
    > vipera (alive-baby-birth-giver = viper) This one seems like a stretch? I'm also curious why you interpret the formation as "noun stem with final vowel changed to i", as opposed to "noun stem followed by epenthetic i".
    - 4y ago
devoutsalsa 4y ago
That’s a rookie telescope. Let’s use the sun! https://youtu.be/4d0EGIt1SPc https://youtu.be/4d0EGIt1SPc

krono 4y ago

There are actual (conceptual :D) plans by NASA to use our own sun as a gravitational lens to achieve just that. The concept is by Slava Turyshev and titled "Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravitational Lens Mission". I'm only a casualstronomer and don't consider myself qualified to provide further details. Should be easy enough to find though!

andyjohnson0 4y ago
Link: https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_I_Phase_II/Direct_Multipixel_Imaging_and_Spectroscopy_of_an_Exoplanet/ https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...

comboy 4y ago

Sun size. https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc

contravariant 4y ago
As in one solar mass of telescope or just a telescope as wide as the sun's radius? The latter seems achievable, if tricky.
- lasc4r 4y ago
  It uses the sun's gravity as a gravitational lens. You fly a normal sized telescope to the focal point. The theoretical resolution is pretty mindblowing, we'd be able to make out oceans and continents on exoplanets.
  - andyjohnson0 4y ago
    The main problem seems to be getting to the focal point, which is 500+ AUs from the Earth.

colechristensen 4y ago

JWST follow up in planning stages named for Carl Sagan is considerably bigger, optical, and being designed to be able to directly image exoplanets. https://youtu.be/BIgQpXObjFI https://youtu.be/BIgQpXObjFI

dakr 4y ago

Well, you can do it with an 8m-diameter primary mirror, because it's been done at Gemini Observatory. Keck and the VLT have directly imaged exoplanets as well. See this list: https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...

eesmith 4y ago
I suspect greesil means resolved beyond a point source. We've so far only managed that for stars: https://en.wikipedia.org/wiki/List_of_stars_with_resolved_images https://en.wikipedia.org/wiki/List_of_stars_with_resolved_im... .

prox 4y ago

Already done! https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...