5 ms·

With current technology it would take nearly 40,000 years to travel a single lightyear… I hope you’re patient. For perspective, Voyager 1 has been hurtling thr

by Fezzik 4y ago

With current technology it would take nearly 40,000 years to travel a single lightyear… I hope you’re patient. For perspective, Voyager 1 has been hurtling through space since 1977 and has travelled a measly .002324439 lightyears. The Universe is mind bogglingly big.

whalesalad 4y ago
Thanks for the perspective, I was curious about this.
Tepix 4y ago
You could use the sun as the lens of a telescope to resolve city-size details on exoplanets. Might be easier to go 500 AU than several light years.
- SturgeonsLaw 4y ago
  That's incredible. How are the photons from the planet not entirely drowned out by those emanating from the sun?
  - deleted 4y ago
    [deleted]
  - robbiep 4y ago
    I don’t know anything specific about what the parent is proposing, but I imagine it is using the mass of the sun as a gravitational lens. Because of the solar radiation there isn’t really much sunlight (read:any) that is directly reflected to an observer peering on the edge of the sun.. light travels in straight lines. Basically, the way scientists used a solar eclipse to confirm the theory of relativity and gravitational lensing of stars ‘behind’ the sun to in front of it. Or like the way certain objects were lensed in the massive JWST shot that came out a couple months ago. But beyond that I know nothing
    - avian 4y ago
      Here's the paper discussing this idea: https://arxiv.org/pdf/2002.11871.pdf https://arxiv.org/pdf/2002.11871.pdf
  - wruza 4y ago
    They take pictures at night when there’s no sunlight.
  - Tepix 4y ago
    When you are using the sun as a gravitational lens you block out the sun and look at the area of the sky around the sun. There's a wikipedia page for the concept at https://en.wikipedia.org/wiki/Solar_gravitational_lens https://en.wikipedia.org/wiki/Solar_gravitational_lens
    - dmix 4y ago
      This is the space project that most excites me and the one I most hope we solve in my lifetime. Much more interesting than Mars (not that you can't do both). This video on gravitational lensing blew my mind https://youtu.be/NQFqDKRAROI https://youtu.be/NQFqDKRAROI What do you think the odds are of if it being done IRL?
- moffkalast 4y ago
  You mean the sun as the Sun or as their local star? Not sure how you'd use ours as a lens.
  - Tepix 4y ago
    I mean using our sun as a gravitational lens. There's a schematic at https://www.planetary.org/space-images/solar-gravity-lens-telescope https://www.planetary.org/space-images/solar-gravity-lens-te... One big problem (besides getting out there - hehe) is that you are looking in one very particular direction and need to move big distances (at a distance of ~500 au from the sun) to look elsewhere. I guess you could wait until the planet you are aiming at does another orbit around its star and flies through your point of focus again. PS Voyager launched in 1971 and is now at 158 au! These distances are truly vast. 1 light year is 63241 au.
holoduke 4y ago
Or are mindbogglingly slow. If we can reach 90% of lightspeed we would have a good Lorentz number to travel the whole milkeyway in a few weeks. We would see a very different earth though when we come back.
- eesmith 4y ago
  Time dilation at 0.9 c is only 2.3x (where 1x is no dilation). Lorentz factor γ = 1 / sqrt(1 - (v/c)²) = 1/sqrt(1 - 0.9²) = 2.29 To travel 87,400 light years at near light speed, in a subjective time of a month requires a dilation of 87400 years * 12 months / year = 1048800, with a speed of: (1-(1/1048800)²) c = 0.9999999999990908 c which is about 0.27 mm/s slower than the speed of light. For comparison, the protons at CERN only hit 0.999999991 c (https://public-archive.web.cern.ch/en/LHC/Facts-en.html https://public-archive.web.cern.ch/en/LHC/Facts-en.html) and the electrons at SLAC only hit 0.99999999995 c (https://www.slac.stanford.edu/pubs/slacpubs/5500/slac-pub-5628.pdf https://www.slac.stanford.edu/pubs/slacpubs/5500/slac-pub-56...).

by Fezzik 4y ago

whalesalad 4y ago

Thanks for the perspective, I was curious about this.

Tepix 4y ago

You could use the sun as the lens of a telescope to resolve city-size details on exoplanets. Might be easier to go 500 AU than several light years.

SturgeonsLaw 4y ago
That's incredible. How are the photons from the planet not entirely drowned out by those emanating from the sun?
- deleted 4y ago
  [deleted]
- robbiep 4y ago
  I don’t know anything specific about what the parent is proposing, but I imagine it is using the mass of the sun as a gravitational lens. Because of the solar radiation there isn’t really much sunlight (read:any) that is directly reflected to an observer peering on the edge of the sun.. light travels in straight lines. Basically, the way scientists used a solar eclipse to confirm the theory of relativity and gravitational lensing of stars ‘behind’ the sun to in front of it. Or like the way certain objects were lensed in the massive JWST shot that came out a couple months ago. But beyond that I know nothing
  - avian 4y ago
    Here's the paper discussing this idea: https://arxiv.org/pdf/2002.11871.pdf https://arxiv.org/pdf/2002.11871.pdf
- wruza 4y ago
  They take pictures at night when there’s no sunlight.
- Tepix 4y ago
  When you are using the sun as a gravitational lens you block out the sun and look at the area of the sky around the sun. There's a wikipedia page for the concept at https://en.wikipedia.org/wiki/Solar_gravitational_lens https://en.wikipedia.org/wiki/Solar_gravitational_lens
  - dmix 4y ago
    This is the space project that most excites me and the one I most hope we solve in my lifetime. Much more interesting than Mars (not that you can't do both). This video on gravitational lensing blew my mind https://youtu.be/NQFqDKRAROI https://youtu.be/NQFqDKRAROI What do you think the odds are of if it being done IRL?
moffkalast 4y ago
You mean the sun as the Sun or as their local star? Not sure how you'd use ours as a lens.
- Tepix 4y ago
  I mean using our sun as a gravitational lens. There's a schematic at https://www.planetary.org/space-images/solar-gravity-lens-telescope https://www.planetary.org/space-images/solar-gravity-lens-te... One big problem (besides getting out there - hehe) is that you are looking in one very particular direction and need to move big distances (at a distance of ~500 au from the sun) to look elsewhere. I guess you could wait until the planet you are aiming at does another orbit around its star and flies through your point of focus again. PS Voyager launched in 1971 and is now at 158 au! These distances are truly vast. 1 light year is 63241 au.

holoduke 4y ago

Or are mindbogglingly slow. If we can reach 90% of lightspeed we would have a good Lorentz number to travel the whole milkeyway in a few weeks. We would see a very different earth though when we come back.

eesmith 4y ago
Time dilation at 0.9 c is only 2.3x (where 1x is no dilation). Lorentz factor γ = 1 / sqrt(1 - (v/c)²) = 1/sqrt(1 - 0.9²) = 2.29 To travel 87,400 light years at near light speed, in a subjective time of a month requires a dilation of 87400 years * 12 months / year = 1048800, with a speed of: (1-(1/1048800)²) c = 0.9999999999990908 c which is about 0.27 mm/s slower than the speed of light. For comparison, the protons at CERN only hit 0.999999991 c (https://public-archive.web.cern.ch/en/LHC/Facts-en.html https://public-archive.web.cern.ch/en/LHC/Facts-en.html) and the electrons at SLAC only hit 0.99999999995 c (https://www.slac.stanford.edu/pubs/slacpubs/5500/slac-pub-5628.pdf https://www.slac.stanford.edu/pubs/slacpubs/5500/slac-pub-56...).