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The habitable zone around a star is based on water and the proteins that make up our body. If we were based on liquid methane like what is found on Titan, we would find the -290 degrees fahrenheit weather nice and balmy. It would be better to say that liquid is essential to life. Though all life we know of on earth uses our abundant liquid water.
If you look at the elements that make us up, all of them except trace elements are abundant in the Universe, and all of them are highly chemically reactive and can make complex molecules. Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Carbon is reactive and can make more different molecules than all other elements combined. Water facilitates chemical reactions. All of those elements except calcium make up DNA which is needed to replicate. Oxygen in the air gives a fast metabolism. Many organic compounds can be naturally made in space. These components are so ideal, you'd have a hard time making life out of anything else.
One thing i wonder: They say life could have traveled to Earth from Mars on the ejected material from asteroid impacts. I wonder if there could be life on Europa that came from earth billions of years ago.
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I try to be helpful. I'm not an expert.
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