Final answer:
The question requires knowledge of the inverse square law of light intensity and distance in astronomy to understand how distances affect the light received by planets. A planet that is twice as far from its star receives 1/4 of the light, while three times the distance reduces the light received to 1/9 due to the inverse square law.
Step-by-step explanation:
The question relates to the inverse square law of light intensity and distance in astronomy, which tells us that the brightness of an object (or the light received from a star) decreases with the square of the distance from the source. Using this principle and the provided example of Star A and Star B having different apparent brightnesses but identical luminosities, we can deduce how much fainter or brighter one star appears compared to the other based on their distances from Earth.
In the case of the planets around a distant star, if we have a planet that is twice as far from its star as another planet, it would receive only 1/4 (or 25%) of the light that the closer planet receives due to the inverse square law. Similarly, if a planet is three times farther, it receives 1/9 (or 11.1%) of the light. For the moons of Jupiter and Saturn, which orbit at 5.2 and 9.5 times farther from the Sun compared to Earth, they would receive approximately 1/(5.2)² and 1/(9.5)² of the light Earth receives, respectively.