Stradric
Amazing stuff. And we've really only just begun searching for these exoplanets. Already we've found a few rocky planets in the habitable zones of their stars.
TJG
"The most interesting of the new planets is the one most distant from the star, HD 40307 g. It has a mass at least seven times that of the Earth and..."
"This is a large planet, but if it has the same average density as does the Earth, it would be about 1.9 times larger in diameter than the Earth. The surface gravity would also be about 1.9 g..."
Gravity is proportional to mass. Wouldn't it be at least 7 g?
Kim Armstead
Why is there an emphasis on discovering habitable planets "close" to Earth? Are people planning to leave? Are we looking for new friends? What's up? Curious...
Thanks. ka
Dave Hargraves
lol only 42 light years away, so if we could travel at the speed of light a newborn sent there, at point of arrival would be 42 years old. our space crafts of today, you would have to live for many thousands of years to make it there alive. its funny that they would say only 42 light years away lol have a nice day regards, Freelance Eng.
TJG
wait... I forgot about the radius...
g=M/r^2
HD's mass = 7xEm HD's radius = 1.9xEr
HD's g = 7xEm/(1.9xEr)^2 = (7/1.9^2)x(Em/Er^2) = (7/1.9^2)xEg =~ 1.94x9.8 m/s^2
...Nevermind.
D.O.R.A.
@kim
Half of the first one and all of the second.
Also travel would be easier going to a more nearby colonized planet.
warren52nz
@TJG 7 times the mass means 7 times the volume. V=4/3 X Pi X Radius cubed If you work it out, this makes the radius 1.9 times that of Earth (as stated above) Gravitational force is proportional to Mass/Radius². If the mass is 7 times Earth's then 7 / 1.9² = 1.9 I think the appearance of 1.9 twice in this is a coincidence but my brain's already hurting. :-)
Gregory Gannotti
Mining! It's all about cold hard cash!
TJG
@warren52nz Right! Thanks. All this assumes a density very similar to Earth's. Guess we'll have to wait and see if that's right.