Earth is currently the only known biosphere. More biospheres means that disasters that muck up one are less likely to muck up everything.
Less seriously, people like things that are cool.
EDIT: Seriously? My most-upvoted comment of all time? Really? This is as good as it gets?
Earth is currently the only known biosphere. More biospheres means that disasters that muck up one are less likely to muck up everything.
Less seriously, people like things that are cool.
EDIT: Seriously? My most-upvoted comment of all time? Really? This is as good as it gets?