Final answer:
Neptune has an internal energy source allowing it to radiate some heat into space, whereas Uranus does not have a measurable internal heat source. Despite this, their atmospheric temperatures are nearly the same. The mechanisms behind their heat radiation differences remain a topic of research.
Step-by-step explanation:
When considering whether Uranus and Neptune radiate more energy than they receive from the Sun, it is noted that these planets are quite distinct in this aspect. Neptune has a small internal energy source, which allows it to emit some heat into space. In comparison, Uranus lacks a measurable internal heat source, although the atmospheric temperatures of the two planets are nearly the same, despite Neptune being further away from the Sun. The reasons for the differences in internal heat between Uranus and Neptune are not fully understood, but it illustrates the diversity of celestial bodies in our solar system. The composition and internal processes of these planets contribute to their ability to radiate energy into space.
Jupiter and Saturn, which are much larger, also display significant internal heating. Jupiter, for one, is known to radiate more energy into space than it receives from the Sun due to its major internal heat source. Similarly, Saturn radiates significant energy. The reasons for these variations among the gas giants and ice giants reveal much about their formation and evolution, suggesting that Uranus and Neptune did not form where they currently orbit but were likely scattered outward due to gravitational interactions with larger gas giants like Jupiter.