Quasars are extremely luminous galactic cores located at great distances from Earth. Here are the key facts about quasars:

1. The nature of quasars. Quasars are active galactic nuclei - supermassive black holes at the centers of distant galaxies that accrete surrounding matter and emit enormous amounts of energy.

2. Quasar radiation. Quasars emit vast amounts of energy, surpassing the total luminosity of normal galaxies. Their power can reach trillions of times that of the Sun. This is due to the high accretion of matter around the black holes.

3. Distances and age. Quasars have been detected at distances up to 13 billion light-years, meaning we observe them as they were in the very early universe, billions of years before the formation of our Solar System.