According to modern concepts, a pulsar is a rapidly rotating neutron star with radio emission. The radio beam emanates from the polar regions of the star, therefore it forms a kind of “searchlight”. The Earth periodically falls under this radiation, so there is a feeling that the star is pulsating. Hence the name.
Quasars are active nuclei of distant galaxies with luminosities trillions of times that of the Sun.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.