A pulsar is a rapidly spinning neutron star that emits radiation in narrow beams focused by the star’s magnetic field. Because the pulsar’s magnetic poles do not align with the poles of its rotational axis, the beams sweep around like the beacon of a lighthouse and are thus observed on Earth as short, regular pulses. Some scientists initially suggested that extraterrestrial civilizations were the source of the strange signals and thus dubbed the first pulsar LGM-1, which is an acronym for what? Discuss