If aliens visited Earth during WW1 or WW11, or one of the current conflict zones in the present time, I should think he/she/it would leave Earth in a hurry and alert other inhabited planets to steer clear of our planet for the foreseeable future!
I appreciate these are translations, but that phrase is meaningless. You can't say "more less than" (ie: twice as less as hot) and even worse "x times less" unless you're comparing two things against a third.
Perhaps the translator meant "less than half as hot"?
After twenty years of research, astronomers have just discovered a planet which looks remarkably like Earth. And that's not all, because further studies will be needed to determine whether life has developed there.