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arXiv:1604.06351astro-ph.EP

Mission to the Gravitational Focus of the Sun: A Critical Analysis

Geoffrey A. Landis

Abstract

The gravitational field of the sun will focus light from a distant source to a focal point at a minimal distance of 550 Astronomical Units from the sun. A proposed mission to this gravitational focus could use the sun as a very large lens, allowing (in principle) a large amplification of signal from the target, and a very high magnification. This article discusses some of the difficulties involved in using the sun as such a gravitational telescope for a candidate mission, that of imaging the surface of a previously-detected exoplanet. These difficulties include the pointing and focal length, and associated high magnification; the signal to noise ratio associated with the solar corona, and the focal blur. In addition, a method to calculate the signal gain and magnification is derived using the first-order deflection calculation and classical optics, showing that the gain is finite for an on-axis source of non-zero area.

arXiv comments
15 pages, 9 figures. Corrected typo in distance
Journal reference
DOI
Subjects
astro-ph.EPEarth and Planetary Astrophysics astro-ph.IMInstrumentation and Methods for Astrophysics gr-qcGeneral Relativity and Quantum Cosmology physics.opticsOptics

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Linked by 6 identifiable commenters in 7 comments across 7 threads, from May 2017 to Oct 2024.

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Discussed in comments7 threads

  1. First images from Euclid are in 1 comment

    • Yes, you'd need to get quite far from the Sun to use it as a lens - about 650 AU is where it starts becoming practical. It would also not be re-orientable, so any "telescope" launched to that location would only be able to observe a single target. (But, notably, it is far easier…

      skykoolerView on HNParent context

  2. The Webb Telescope further deepens the Hubble tension controversy in cosmology 1 comment

    • https://www.centauri-dreams.org/2020/12/10/developing-focal-... (and its critical analysis) https://arxiv.org/pdf/1604.06351 I believe that work on such a project would be interesting, even if it isn't ever done. It is something that if you worked on it as a grad student, and…

      shagieView on HNParent context

  3. Building telescopes on the Moon could transform astronomy 1 comment

    • If you're interested in a critical review of FOCAL (which is also rather interesting) - https://arxiv.org/pdf/1604.06351.pdf I am on the "this is a really hard problem - but an interesting one" category. It seems like it will take a number of significant improvements on top of…

      shagieView on HNParent context

  4. Interstellar Probe, a Mission Concept for NASA 1 comment

    • So if this probe is bound to venture into the distance range useful for a solar gravitational lensing telescope, why not use it to deploy one? That would really be a major breakthrough IMHO. https://arxiv.org/abs/1604.06351 "The minimum distance for a solar lensing telescope is…

      aruggirelloView on HNParent context

  5. Direct Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens 1 comment

    • For a more critical look at this concept, I recommend "Mission to the Gravitational Focus of the Sun: A Critical Analysis". https://arxiv.org/abs/1604.06351

      sanxiynView on HNParent context

  6. Four Earth-sized planets detected orbiting the nearest sun-like star 1 comment

    • In principle, I am right with ya. We need ways of beating (or at least coping with), the diffraction limit. It's fun to think of, say, stuff like this: https://arxiv.org/abs/1604.06351 (as far as big lenses go) Using the sun as a gravitational lens would be pretty sweet. I have…

      tobmltView on HNParent context

  7. Interstellar Communication via Gravitational Lens 1 comment

    • Actually the proposal is a bit more complicated than using a 12 meter large antenna, it is sending this antenna at 550 AU (the FOCAL in "FOCAL antenna"). Geoffrey A. Landis wrote: "The gravitational field of the sun will focus light from a distant source to a focal point at a…

      JPLeRouzicView on HNParent context

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