Timeline for How can Ganymede have an Earth-like gravity without us having realized it?
Current License: CC BY-SA 4.0
7 events
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| Sep 24, 2018 at 6:09 | comment | added | Oscar Bravo | I think you were right the first time... To get the same gravitational acceleration (at the surface) as Earth (9.81$m/s^2$), but keep the same radius, Ganymede (1.5$m/s^2$) needs only to get about 7 times heavier ($a \propto m$), therefore 7 times more dense. Its current density is about 2$g/cm^3$ so that takes us to about 15$g/cm^3$. Which is easily attainable with normal matter. | |
| Sep 21, 2018 at 14:52 | history | edited | Ruadhan | CC BY-SA 4.0 |
Went away and did the research.
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| Sep 21, 2018 at 14:34 | comment | added | Ruadhan | Osmium is 22590kg/m^3, still not viable for this, and Hassium (the densest material ever made in a lab) is a little denser at 22610kg/m^3. | |
| Sep 21, 2018 at 14:28 | comment | added | Ruadhan | Just went and did some figuring. Iron is 7850kg/m^3, while Tungsten is 19600kg/m^3. So technically speaking it's somewhere between 2 and 3 times as dense. You'd need something 5 times more dense than tungsten to achieve earthlike mass with Ganymede. Uranium is less dense than Tungsten at 18900kg/m^3. So yes. you'd probably need an artificial super-dense element. Good luck manufacturing one that isn't a ridiculously short-lived radioactive element. | |
| Sep 21, 2018 at 14:23 | comment | added | Ruadhan | Disclaimer. I have no idea whether a core of tungsten and uranium deposits would be sufficient to produce an earth-like mass! But checking vs Iron by molar weight would probably be a useful comparison. | |
| Sep 21, 2018 at 12:38 | comment | added | Oscar Bravo | I was out by 10 in my density calculation and thought that you'd need an artificial super-dense element... Bit disappointed you only need tungsten. | |
| Sep 19, 2018 at 15:25 | history | answered | Ruadhan | CC BY-SA 4.0 |