Please all of this before u answer plz?

Question

if the size of the sun can change the sweet spot there life can evolve and the size or the planet why is it we only go by the information here on earth. why can't we think of live even human life of a larger scale

Answer 1

You seem to assume that scientists are only looking for life as we know it on Earth.  But that is not exactly true.

There are a number of groups working on what life would look like in different environments (very hot or very cold worlds, worlds with no oxygen, worlds with no water).

But right now, the only kind of life we know is what is on Earth, so that is the kind of life we have to start looking for.  We will know it when we find it, and we know what to look for.

Answer 2

what is your point?

somewhere, you have a question, and I don't think you asked it.

the more we know about planets outside our Solar system, the more likely we will be able to understand how different life could evolve.

as it is, can you blame us if we seem a little self-centered?

Answer 3

Indeed, Venus has shown that a strong green house can make a planet warmer than it would be for a given distance.  A Venus style green house on Mars would make it toasty warm.  So the "habitable zone" could easily be considerably farther from the Sun.

The same is true for extrasolar planets.

Check out Frank Drake's audio show at the link below.  That's fairly representative in current SETI thinking on where to look.

Answer 4

Every star has a "habitable zone," where the conditions for what we call life are capable of existing.  Too hot or too cold, and there is no liquid water available.  Liquid water is essential for life (as we currently define it).

This habitable zone will vary from one star to another, due to varying heat outputs.  Still, if a planet's orbit doesn't occupy that zone, life is impossible.

Although, perhaps our definition of life is indeed flawed.  Maybe there is a way for life elsewhere to not develop a need for water, it could evolve to metabolize different nutrients, and keep it's cell structure hydrated with some other liquid.  This is highly speculative though.

All life on earth is carbon based, but, some have speculated that silicon based life forms could function very similar, and no one has ruled that possibility out.  

Answer 5

It is thought unlikely that life can exist with different basic chemistry to our own (nitrogen based molecules, etc). Therefore the planets that are thought of as possible to have life are those that have temperatures that are within a certain range where certain important metabolic reactions take place. It is also thought that life needs liquid water to exist, which will occur within a relatively small temperature range. Planets where life is thought to be possible can be a lot larger than Earth (one planet discovered last year was such a case) so long as the temparature is relatively similar to Earth (as well as stable).