1. Four Ways Scientist's Detects Planet's Are : 'Radical Velocity', 'Astrometry', 'Transit Method', and 'Optical Detection'.

2. 'Optical Detection' makes the most sense to me. Basically they use the the planets light waves to detect where the planet is. Also they use a cornograph to block everything but the stars corona to expose the planet.

3. Otherwise known as the Habitable Zone, The Goldilock's Zone Is when a planet is just the right distance from the home star and it's surface is just right ; neither too cold or too hot.

4. The Planet Gilese 581c Seems so much similar to Earth That I Think It would be know as the "Earth's Twin". The Appearance may be the only difference ; regarding the plethora of ocean's and gravity. But If It was a livable planet , I would think that would be the only way from Earth if Global Warming struck or any other catastrophe.

5. It's Hard To Answer. Because All My Life I Was Brought Up on Opinion and Not Scientific Fact. Obviously, Most Children are told No , Aliens aren't Real ; Right along With The "Tooth Fairy" and "Santa Claus". But, from every fact I've recently read, They Seem Possibly Exist-able. Now some stuff I don't believe is : Their Nomads that will overrule the Earth and Destroy Human-Kind. I Also Don't Believe That Their Harmful . If I'd have to guess , I'd Go Off Rod Sterling's Twilight Zone. He Makes Aliens Seem Just Like Humans Except A little Weirder. Like They Have Super-Natural Power , but They Look and Seem Just Like Living, Breathing Humans. The Only Difference May Be That , Their Diet Is A little Awkward [ lol ) * .