4 ms·
What's the gravity on the surface? It's 2.4 times the size of earth, is the density the same? If so, that amount of gravity may very well make it uninhabitable.
by jjcm 15y ago
What's the gravity on the surface? It's 2.4 times the size of earth, is the density the same? If so, that amount of gravity may very well make it uninhabitable.
- cryptoz 15y agoThey don't know the density yet, but future observations should tell us. Probably next year, I think.
- nickpinkston 15y agoWait - we can't infer this using orbit size and speed plus the volume of body? Is it more about distribution of density throughout the body?
- cryptoz 15y agoI'm not sure what we know about this particular planet so far, but I think the part that's missing is volume. Currently, nobody knows what the composition of the planet is. We don't know if it's liquid or solid, for example. I think.
- cbr 15y agoThe radius is known (2.4x earth), so why wouldn't we have the volume?
- Tossrock 15y agoOrbit size and speed have no relation to planetary density by themselves. If we knew the total kinetic energy of the planet, then they would, but we don't.
- nickpinkston 15y agoSo you're saying that we can't get the weight using it's speed, orbit radius and planet volume? I think I remember this question on my Physics I test! http://en.wikipedia.org/wiki/Centripetal_force#Formula http://en.wikipedia.org/wiki/Centripetal_force#Formula We have: r, v, m-star, f-star - so m-planet follows right?
- Tossrock 15y agoWe don't have "f-star"; the centripedal force (or the force of gravity in this case) is the product of both the mass of the star and the mass of the planet, which we don't have.
- mirkules 15y agoHumans can withstand much more than 2.4Gs although the time is exponentially and inversely proportional (for example, 3Gs is a space shuttle launch for a number of minutes, 10Gs is the maximum force allowed during space capsule landing, but only for a few seconds). Therefore, I wouldn't say "uninhabitable," but probably less friendly (and not immediately lethal) to humans. Also, different animals have different thresholds -- mice, for example, have a much lower tolerance for G-forces than whales. I recommend reading "Packing for Mars" by Mary Roach -- very insightful book that discusses all sorts of things about planet habitability, space travel, space suit design, psychology, and among many other things, G-forces.
- beambot 15y agoThat's curious... I would have thought a land-dwelling mouse would have more G-force tolerance than a whale living in neutral buoyancy oceans. Are you using that as an illustrative example (eg. mice and elephants), or does that still hold for mice and whales?
- mirkules 15y agoYou're right, it was a bad example. I just looked through the book I referenced, this is what it said (p. 126): "...a beached whale will die from an overdose of gravity... The whale's diaphragm and rib muscles aren't strong enough to expand its lungs and raise the now far heavier blubber and bone that press in on them, and the animal suffocates." It goes on: "You can see what a rat's organs look like inside its body at 10 G's and 19 G's [in] the February 1953 issue of Aviation Medicine... Anesthetized rats were immersed in liquid nitrogen while riding a centrifuge... Heavier blood in the heart has pooled at the bottom of the organ and weighed it down, elongating it like a wad of stretched Silly Putty... This is why the astronauts lie down during reentry -- so the blood doesn't pool in their legs and feet" I wish I could say I was using it as an illustrative example... But I just remembered it wrong :)