Planetary Resources may upgrade crowdfunded satellite into alien-finder The Kickstarter campaign to build a satellite for public use is going better than expected, according to asteroid mining company Planetary Resources, and so it has extended its revenue target to help fund hardware upgrades to enable the orbital platform to search for exoplanets. The campaign, which seeks to partially fund an …
Not sure gravitational lensing is sufficiently powerful to make a visible deflection around a 1AU or so sphere with 'only' the mass of the sun; that's not a very dense thing at all and I think you'd need something a lot denser.
On the other hand, a Dyson sphere *must* emit the entire energy of the star as infra-red (since the point of the sphere is that the civilisation that built it needed all the energy from the sun, and it can only leave as waste heat), so if you find a star-sized IR source with no visible light associated, you've probably got one.
Would it not be much, much larger than star-sized? The useful surface of such a structure would probably have to be built at a distance equivalent to the orbital path of a planet in the "goldilocks" zone.
It wouldn't be worth visiting any stars for a vast distance around such a structure as any resource bearing planets would probably have been stripped bare to supply the incredible demand for buildng materials.
I don't know if I'm a fan of the Dyson sphere/shell idea. It seems to me that if a civilisation can build such a thing, then they probably have energy requirements beyond the ability of a single captured star to repay.
If they did require such a thing, then they probably have radiation manipulating capabilities to reduce the observable footprint of the structure and so stop it advertising itself as a target. Or perhaps it doesn't matter as anything of that size made out of a substance which can support its own mass would surely be largely invulnerable to harm.
Not sure gravitational lensing is sufficiently powerful to make a visible deflection around a 1AU or so sphere with 'only' the mass of the sun; that's not a very dense thing at all and I think you'd need something a lot denser.
Yes, it is. In fact, one way that planets are inferred to exist is that they alter the lensing effects of the star around which they orbit. In other words, Star A bends light coming to us from Star B. Star A has a planet orbiting it which bends the light from Star B even more when it is in the correct position in its orbit, allowing astronomers to estimate its mass based on this effect, which in turn allows them to estimate its distance from the star based on its orbital period.
Might not Star B be the one with the planet? How can you tell?
Notice that I mentioned "astronomers" and "they" rather than attributing this to my personal experience. I would imagine that it has to do with the way gravitational lensing works: you are bending light from one object around another. In such cases, you may end up with multiple images of the same source. If one of the sources produced by gravitational lensing changes in such a way as to suggest a planet while the other source (or sources) does not, I guess that would indicate the star bending the light has an associated planet rather than the star producing the light. There might be another tip off that an actual boffin might be able to explain.
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