# If an exoplanet like Kepler 442b, the most likely to be habitable exoplanet, has a mass 2.34x that of earth, would the gravity of the planet be 2.34x that of earth as well? Also, how would this affect humans if they were to travel there?

376 views

If an exoplanet like Kepler 442b, the most likely to be habitable exoplanet, has a mass 2.34x that of earth, would the gravity of the planet be 2.34x that of earth as well? Also, how would this affect humans if they were to travel there?

In: Physics Depends on the size of the planet. Gravity increases proportionately with mass but inversely proportionately with the square of the distance.

Consider the Moon. The mass is 0.0123x Earth, but its (equatorial) radius is 0.2725x Earth. Combining these gives us:

(0.0123/0.2725^(2)) = 0.1656… which is around 1/6th the gravity of Earth, which is what we observe.

So, if Kepler 442b was simply 2.34 the mass of Earth but also the same size then, yes, it would be 2.34x the gravity of Earth. But it’s radius is 1.34x Earth which gives us:

(2.34/1.34^(2)) = 1.3032… so it is about 30% more gravity than Earth. The gravity of Kepler 442b is about 30% stronger than Earth (assuming it has about the same kind of environment as ours). It would certainly feel heavy, and it would cause some major wear-and-tear on our bodies that didn’t evolve with that kind of pressure in mind. It could be a lot colder than Earth, too, which could cause some other issues, and the axial tilt is probably much smaller as well, so it wouldn’t have anything like Earth’s seasons. Gravity is proportional to distance and mass. The earth is the densest large object in our solar system, so it has unusually high gravity relative to its mass. In fact, our core is so dense, that as you go below the surface, acceleration due to gravity actually goes up for awhile as you get closer to the core.

What all that means is a planet 2.34x earth’s mass would likely have higher surface gravity, but definitely not 2.34x. Could a real life “Superman” exist if a child would be born on Kepler and travel back to earth when he is all grown up. So all of his childhood would be with a gravity greater than the one on earth?