Final answer:
The higher intensity of the sun during Mars's southern hemisphere summer is because Mars is closer to the sun at this time due to its elliptical orbit and the sunlight strikes the surface more directly due to Mars's axial tilt.
Step-by-step explanation:
The intensity of the sun is higher during the summer in Mars's southern hemisphere compared to its northern hemisphere due to the axial tilt and elliptical orbit of the planet. When the southern hemisphere is tilted toward the sun, Mars is also closer to the sun in its orbit, making the sunlight more intense. This contrasts with Earth, where the distance to the sun does not vary as much across seasons because of its more circular orbit.
Mars's elliptical orbit combined with its axial tilt causes the southern hemisphere to experience more extreme seasonal changes. During the southern summer, Mars is at perihelion, the point in its orbit where it is closest to the sun. As a result, the sun's rays strike the southern hemisphere more directly and intensely, leading to higher temperatures.
The angle at which sunlight strikes a planet's surface plays a significant role in determining the intensity of the heat it receives. Similar to Earth, when Mars's southern hemisphere is tilted toward the sun, the sunlight hits at a more direct angle, effectively increasing the solar heating of the surface, similar to shining a flashlight directly onto a wall rather than at an angle.