According to Kepler's second law of planetary motion, the line joining a planet and the Sun sweeps out equal areas in equal intervals of time. This means that during any given period, such as the 31 days of January or the 31 days of July, the area swept out by Earth’s orbit around the Sun is the same regardless of Earth’s distance from the Sun at those times. Even though Earth is slightly closer to the Sun in January (perihelion) than in July (aphelion), it moves faster in its orbit when closer to the Sun and slower when farther away. The increased orbital speed in January compensates for the shorter orbital radius, so the area swept out during the 31 days of January is equal to the area swept out during the 31 days of July

. In summary:

• Earth’s orbit sweeps out equal areas in equal times (Kepler’s second law).
• The area swept out in 31 days of January equals that in 31 days of July.
• Earth moves faster when closer to the Sun in January and slower in July to maintain this equality.

Thus, the area swept out by Earth’s orbit around the Sun during the 31 days of January is the same as the area swept out during the 31 days of July