The scientists determined that the planet, which they have called Gliese 581g, has a mass three to four times that of Earth and an orbital period of just under 37 days.
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If Gliese 581g has a rocky composition similar to Earth’s, its diameter would be about 1.2 to 1.4 times that of the Earth, the researchers said.
The surface gravity would be about the same or slightly higher than Earth’s, so that a person could easily walk upright on the planet, Vogt said.
If it’s mass is three times that of Earth and its diameter 1.4 times that of Earth, gravity would be 1.5 Earth gravities. A lighter mass would mean a smaller diameter, so a more realistic minimum would be 2 Earth gravities, which is what you get from assuming 3 times Earth mass and 1.2 Earth diameters. Thus, it seems a bit strange to say that the surface gravity could be about the same. True, a person could walk upright in that gravity, but it would not be comfortable.
If almost all bodies have gravities >10g, or <0.1g, then saying 2g is about the same as 1g is perfectly reasonable. Of course, by that standard all the inner planets in our solar system have about the same gravity.
If it’s mass is three times that of Earth and its diameter 1.4 times that of Earth, gravity would be 1.5 Earth gravities. A lighter mass would mean a smaller diameter, so a more realistic minimum would be 2 Earth gravities, which is what you get from assuming 3 times Earth mass and 1.2 Earth diameters. Thus, it seems a bit strange to say that the surface gravity could be about the same. True, a person could walk upright in that gravity, but it would not be comfortable.
“about the same” is a relative term.
If almost all bodies have gravities >10g, or <0.1g, then saying 2g is about the same as 1g is perfectly reasonable. Of course, by that standard all the inner planets in our solar system have about the same gravity.