Gravity and Orbiting Objects — Practice problem

Did you know that the average temperature in January in Moscow is similar to the northern United States? Did you know that all of Moscow's seasons are similar to the United States because Earth's axis is tilted $23.5$ degrees?

There is a common misconception that the change in seasons results because the tilt of the Earth makes the North closer to the Sun in the summer and farther in the winter. In actuality, the seasons are caused by the directness of the sun's rays hitting the tilted Earth.

To see that distance can't be the culprit, pretend that the Earth's orbit is a perfect circle of radius $1.5\times10^{11}$ meters, the Earth itself is perfect sphere of radius $6.4\times10^6$ meters, and you are standing in Moscow (at $55.8^{\circ} \text{ N}$ latitude). Assume that the energy from the Sun is inversely proportional to the square of the distance from the Sun.

Based on distance alone, what is the percent difference in solar power received at a point in Moscow, between when the sun is at the highest point in the sky on the summer solstice and winter solstice?