Who makes the legally enforceable promises in a unilateral insurance policy?

Unilateral Contract — a contract in which only one party makes an enforceable promise. Most insurance policies are unilateral contracts in that only the insurer makes a legally enforceable promise to pay covered claims.

i do not get the question.

it would take 95 years for that supernova to be visible on earth, so the year would be about 2113. i hope i did my calculation right.