Timeline for 5km artificial planet, with same gravity as on Earth
Current License: CC BY-SA 4.0
16 events
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| Jun 24, 2020 at 7:00 | comment | added | 4.12.22.4.18.0. | Have you tried thinking about the density expected of the planet? I mean, is there any element dense enough or would you have an atomic bomb at your feet? Radius of 5km & 7,35*10^17 kg of mass to have 9.81 m/s^2 on the surface. That's 1404,477 g/cc. That's denser than osmium. It may be neutron soup from a neutron star. However, I doubt that there is any type of canister able to contain that. Unless applied phlebotinum. | |
| Sep 4, 2018 at 17:24 | history | edited | user | CC BY-SA 4.0 |
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| Jul 6, 2018 at 2:09 | history | edited | Gryphon | CC BY-SA 4.0 |
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| Jul 5, 2018 at 15:59 | comment | added | Cort Ammon | @CJDennis Thanks for that catch. Edited. Even while writing it, I got an inkling that I was skipping something, but I couldn't remember what (1 2, skip a few, 99, ... singularity?) | |
| Jul 5, 2018 at 15:59 | history | edited | Cort Ammon | CC BY-SA 4.0 |
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| Jul 5, 2018 at 15:58 | comment | added | Cort Ammon | @Geliormth You're right. I did sidestep the fact that smaller radii means more less mass for the same accelerations. However, that doens't change the answer. In fact, it makes it more extreme. What we see from these equations is that the radius goes up as mass goes down. It does so quickly that, even by the Earth mass point, you are talking about normal matter rather than degenerate matter. This means you no longer have "white dwarf matter" in the core, you have garden variety matter.. .you basically have a non-exotic asteroid. Might as well have left the rocks in. | |
| Jul 5, 2018 at 15:28 | comment | added | P.Lord | And i was saying yes you are correct however changing it to fit the question just makes it even less viable | |
| Jul 5, 2018 at 15:27 | comment | added | user26494 | @P.Lord, I'm not saying that it's viable, just that the question was not about putting 1 earth mass into a 5km orb, but putting high enough density mass, but much less than 1 earth mass, into a 5km orb so it would have earth gravity at it's surface. | |
| Jul 5, 2018 at 14:14 | comment | added | P.Lord | @Geliormth you just stated your problem. The whole basis is that much less mass = much less density. All high density matter is because of gravity so remove mass and remove density. There is a reason why you don't see tiny stars with little mass. If you read the question he makes this very clear. | |
| Jul 5, 2018 at 9:13 | comment | added | user26494 | Why are you looking at 1 Earth mass to generate earth like gravity at the surface? The whole idea was Earth like gravity at 2.5km radius from the centre of the planet, not at earth radius from the planet, therefore much less mass (but higher density) is needed. | |
| Jul 5, 2018 at 6:48 | comment | added | vsz | (yes, a problem would be that useful densities will be only at the very bottom of it) | |
| Jul 5, 2018 at 6:42 | comment | added | vsz | Just a note regarding your last sentences: you woudln't need a 100 km atmosphere. If the radiation shielding is done with other means, a few dozen (or few hundreds) meters of atmosphere would be enough for the protagonists. | |
| Jul 5, 2018 at 6:15 | comment | added | CJ Dennis | Minor issue: according the neutron star Wikipedia article, above 1.4 solar masses an expired star becomes a neutron star. It becomes a black hole above 3 solar masses. | |
| Jul 4, 2018 at 20:04 | comment | added | Cort Ammon | @M.A.Golding Escape velocity has the same inverse square of the radius term. The same logic applies. | |
| Jul 4, 2018 at 19:38 | comment | added | M. A. Golding | The question is not the "surface gravity" at the edge of the atmosphere, but the escape velocity at the edge of the atmosphere. the artificial planets need to have one Earth gravity at the surface for the heath and comfort of the inhabitants, but need to have a high escape velocity at the edge of the atmosphere, and that is calculated by a different formula. | |
| Jul 4, 2018 at 19:05 | history | answered | Cort Ammon | CC BY-SA 4.0 |