Hi guys, me again, with two questions. Just saw a documentation about supernova, when supernova happens, a huge amount of gamma ray is emitted since it is vacuum in space, why wouldn't the gamma ray hit us? Even if its far and takes a few thousand years for it to reach us, it would eventually reach us right? About comets, i know it is composed of ice, but what actually propel it? The comets need a force to act on it so that it could move ? Thanks in advance and sorry for my poor english.