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The Earth is closest to the sun in early January (perihelion) and farthest in early July (aphelion). It’s a misconception that distance causes the seasons. The primary reason for seasons is the Earth's axial tilt, which causes different hemispheres to receive more direct sunlight at different times of the year. When the sun's rays hit Earth at a more direct angle, the same amount of energy is concentrated over a smaller area, leading to warmer temperatures. In contrast, when the sunlight is more spread out due to a less direct angle, it results in cooler temperatures.
Closest and farthest points
◦ Closest (Perihelion): Early January, when the Northern Hemisphere experiences winter.
◦ Farthest (Aphelion): Early July, when the Northern Hemisphere experiences summer.
Why seasons are caused by Earth's tilt, not distance
◦ Concentrated energy: When a hemisphere is tilted towards the sun, its sunlight hits the surface at a more direct, perpendicular angle. This concentrates the sun's energy over a smaller area, causing it to heat up more and resulting in summer.
◦ Spread-out energy: When a hemisphere is tilted away from the sun, its sunlight hits the surface at a more oblique, spread-out angle. The same amount of solar energy is spread over a larger area, making it less intense and resulting in cooler temperatures and winter.
◦ Distance has a small effect: The difference in distance between perihelion and aphelion is about 3 million miles, which is not enough to cause a significant change in the seasons compared to the effect of the axial tilt.
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