if everything was perfect and we'd find an earth like planet

[sh4d0wl1ne]

there would always be the problem about the gravity...

Even if it would be almost the same exact size (highly unlikely anything like it is near us), still I'm not sure there would be the same gravity.

How is the gravity on Mars?

This is just another of the problems about using another earth like planet.. Even if you go thru everything possible (which at some point could be)

there will always be the gravity problem.. We couldn't live normally on a earth like jupiter sized planet, or on a smaller earth like planet like venus in size..

I don't even know how does gravity really work, I tried reading about it, but rly I don't get it much in the practical ways.. I am sure the size of the planet is one of the biggest gravity influences ?

 

[MeteorWayne]

Mars really isn't very earth like. It's small, and much less massive. It has almost no liquid water (if any) on it's surface. It has almost no atmosphere (compared to earth). It has no magnetosphere to protect it from solar radiation or the solar wind.

The primary factor in gravity is mass, a secondary effect of surface gravity is how big the planet is.

Actually, Venus' surface gravity is very close to earth's, since it's close to the same mass and size. Of course there's that 800 degree sulphuric acid/CO2 atmosphere to deal with....

 

[sh4d0wl1ne]

yeah,

I'm saying, that if we ever found a habitable planet, we probably couldn't really use it to live normally because of the gravity issue.

 

[Invalid]

If you found one the size of Earth you could. Its not impossible to find one that size.

 

[MeteorWayne]

sh4d0wl1ne,

Read what I wrote. It's a matter of mass and size, so there's no reason there can't be planets with earth like gravity (like Venus, as I said). In fact, that would almost be part of a definition for earth-like, don't you think?

 

[ramparts]

Indeed. The definition of Earth-like is same distance to its host star relative to the star's size (i.e., being in the same "habitable zone"), having the same mass, and the same size. We decide how Earth-like a planet is by seeing how closely it fits those criteria. Judging by how frequent planetary systems are out there, I would venture that it's almost certain planets that more or less fit that bill, and in abundance.

Also, as MW said, there is a trade-off between size and mass. A bigger (as in, physically larger) planet than Earth but with a bigger mass would have similar gravity to Earth's, as would a smaller but lighter planet, so long as the proportions of the size as mass are right (for example, Jupiter is obviously bigger and more massive than the Earth, but it's so much more massive compared to how much bigger it is that it has about 2.5 times greater surface gravity).

If you're comfortable with a little math, the surface gravity is proportional to the mass of the planet divided by its radius squared. Alternatively, you can think of it as being proportional to the planet's density multiplied by its radius. So Jupiter is less dense than Earth, but also bigger. It's about 1/4 as dense, and 11 times as large in radius. Multiply 1/4 by 11 and you get roughly 2.5, which is how much more gravity Jupiter has at its surface

 

[ScienceExplorer]

Have we discovered the whole selection of planets beyond this universe?
Let me answer that for you my friends, no, we haven't had we but we've got a great chance that their is another type of life form that may be still alive or buried deep into the crust of the planet.
Still we haven't gotten an answer but the same Gravity level of earth is very limited, like their isn't a habitable planet out there that's a duplicate of earth.
Your chances are very thin to find a duplicate of earth, but their could be another life form out their awaiting for an alien (us) to land onto their earth.
There are many different revolutions that possibly exsist, but their is only one planet out their that used to or currently has living organisms on their or bacteria or a piece of living matter, who knowns but their has to be a way to reach that limit.
Hopefully, we could think of a project that could set us through millions of miles to reach our destination of another habitable planet.
-Thank you!

 

[Fallingstar1971]

Assume everything went right, lets say for the point of discussion, tomorrow a planet is discovered in orbit of Alpha Centauri in the goldilocks zone. Spectral information shows a certain degree of methane in the atmosphere and water vapor has been detected. So life and water are speculated to exist.

Now what?

1. Should we go there and make contact, or should I say, Would it be right to make contact? If not, how could any one nation prevent any other nation from violating this and making contact?

2. If intelligence were detected, chances are they would be experiencing the same problems we are, and if by some chance they are not, they soon will be if we make contact.

3. Different planet, different biosphere. We could catch or even infect alien life with viruses and bacteria that neither have antibodies for. We could very well be harbingers of death for any life encountered (and vise versa).

Do we really have the right to trash our house and then go trash someone elses?

Dont get me wrong, I am all for exploration and the furthering of the knowledge of mankind. But lets keep it real. We are not ready. For starters, we need to realize that we are all humans (or Terrans, Earthlings, Whatever) point is, we are ONE people. Not Americans, or Russians, or Iranians, or whatever.....WE ARE HUMANS.

The second thing we need to get over is that philosophy and religion are the same thing. Neither one is worth killing or dying over. If your God requires you to kill or die, then he is not an all loving all forgiving God is He? Once we are over that, and once we can accept each other and act as one, then and ONLY then will we be able to tolerate an entirely different planetary society. If we try before this, we will come off as hypocrites to any being with any intelligence what so ever. How can we convince an Alien that "We come in peace", when all humanity has ever known is war?

So as you can see, there are "heavier" issues than gravity to be dealt with

I started another thread entitled "Are we ready". I think it would be wise to discuss policies, I have already drifted off topic and dont want to ruin your thread.

Star

 

[centsworth_II]

there would always be the problem about the gravity....
We couldn't live normally on a Earth like Jupiter sized planet...

A Jupiter-sized planet is definitely NOT Earth like! Part of what makes a planet Earth like is its size. And any planet that is the same size as Earth and made of the same rocky material would have the same gravity.

True, there could be rocky planets similar to Earth but several times larger. These would have much more gravity than we are used to and humans would have trouble on them. Or there could be planets a little smaller -- like Mars -- with maybe half the gravity. That might actually be kind of nice to live in. Enough gravity to keep our bodies in shape, but moving things around would be a lot easier.

 

[silylene]

If Neptune had a solid surface, its surface gravity would be only 1.19x that of Earth. It is much larger, with more mass, but less dense. So it works out to have a very similar surface gravity.

Similarly, Uranus, which if it had a distinct surface, its surface gravity would be only 0.89x that of Earth.

However both of these 'ice giants' have massive atmospheres of H2, He, H2O, NH3 and a little methane which is so thick and heavy that it is compressed into a supercritical fluid, which then envelops an inner silicate core. Because the amtospheric gas is slowly compressed with depth into a supercritical fluid, the boundry between the gas phase and the fluid phase will be indistinct. As such, there may be no true 'surface'.

Neither Uranus nor Neptune would be amenable to any kind of life as we know it.

 

[kg]

Could sh4d0wl1ne have read an article about serching for exoplanets and gotten confused? There seems to have been a buzz in the press about now being able to discover planets smaller than Jupiter and having rocky surfaces. I've seen these rocky planets described as "super Earths" even though they arn't very Earth like.

 

[aaron38]

I've been thinking on this, and I think to sucessfully colonize a world with a fully functional branch of human civilization, the surface gravity would have to be within the range of 0.5g to 2.0g. A 200lb male would still get enough daily exercize if he weighed 100lb, and there are 400lb men, the frame will support it. Outside of those bounds I think you'd either have problems with pregnancy and normal childhood growth development, or just be too heavy to move. Actually, Mars is probably within the lower bound (at least, I hope it is) so let's call it 0.3g to 2.0g, and just figure that that's the ratio of the planet to Earth in mass as well. Similar densities and all.

 

[1of6Billion]

I've been thinking on this, and I think to sucessfully colonize a world with a fully functional branch of human civilization, the surface gravity would have to be within the range of 0.5g to 2.0g. A 200lb male would still get enough daily exercize if he weighed 100lb, and there are 400lb men, the frame will support it. Outside of those bounds I think you'd either have problems with pregnancy and normal childhood growth development, or just be too heavy to move. Actually, Mars is probably within the lower bound (at least, I hope it is) so let's call it 0.3g to 2.0g, and just figure that that's the ratio of the planet to Earth in mass as well. Similar densities and all.

Well..let Darwin sort THAT out :lol:
You'll get very distinctively different species of mankind :ugeek: