4 ms·

> Midway in mass and size between Earth and giant worlds like Neptune, such worlds may either be mostly gassy worlds offering slim chances for life as we know i

by acqq 8y ago

> Midway in mass and size between Earth and giant worlds like Neptune, such worlds may either be mostly gassy worlds offering slim chances for life as we know it, or instead super-sized versions of our own habitable, rocky world. However: > Astronomers say they may have detected a second planet ... with a minimum mass roughly six times that of our planet’s. If it's a planet 6 times more massive than Earth, it's a gaseous planet, and nothing like Earth: https://www.forbes.com/sites/startswithabang/2016/11/08/is-earth-our-solar-systems-missing-super-earth/ https://www.forbes.com/sites/startswithabang/2016/11/08/is-e... So don't expect that humans will ever land on that, even if they reach it once (for it rotating around the nearest star). Apparently "super-sized versions of our own habitable, rocky world" can be just slightly bigger than Earth.

gassyEarth 8y ago
Doesn't 6 times the mass get ~6 times the gravity, if we're talking about a rocky planet of comparable density? If I weigh 600 Kg on a super-sized version of earth, it doesn't matter what amount of water or atmosphere is present. It's not habitable, even if it's a temperate 30 degrees celsius, with refreshing sun showers and a briney primordial soup.
- acqq 8y ago
  "6 times the mass get ~6 times the gravity, if we're talking about a rocky planet of comparable density?" There's no such thing, apparently, see the link I've already posted. According to the latest research, six times the Earth mass the planet is gaseous (Neptune-like). The limit over which the planet is Neptune-like is just two times Earth mass, which corresponds to just a little bigger radius than Earth's: "a world that's 2.0 Earth masses and rocky will only be about 25% larger in radius than Earth; larger than that and you're probably Neptune-like, with a massive hydrogen/helium envelope." https://www.universetoday.com/22070/surface-of-neptune/ https://www.universetoday.com/22070/surface-of-neptune/ "In short, there is simply no way one could stand on the “surface of Neptune”, let alone walk around on it."

by acqq 8y ago

gassyEarth 8y ago

Doesn't 6 times the mass get ~6 times the gravity, if we're talking about a rocky planet of comparable density? If I weigh 600 Kg on a super-sized version of earth, it doesn't matter what amount of water or atmosphere is present. It's not habitable, even if it's a temperate 30 degrees celsius, with refreshing sun showers and a briney primordial soup.

acqq 8y ago
"6 times the mass get ~6 times the gravity, if we're talking about a rocky planet of comparable density?" There's no such thing, apparently, see the link I've already posted. According to the latest research, six times the Earth mass the planet is gaseous (Neptune-like). The limit over which the planet is Neptune-like is just two times Earth mass, which corresponds to just a little bigger radius than Earth's: "a world that's 2.0 Earth masses and rocky will only be about 25% larger in radius than Earth; larger than that and you're probably Neptune-like, with a massive hydrogen/helium envelope." https://www.universetoday.com/22070/surface-of-neptune/ https://www.universetoday.com/22070/surface-of-neptune/ "In short, there is simply no way one could stand on the “surface of Neptune”, let alone walk around on it."