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The average distance from the Earth to the Sun is 150 million km. Keep in mind that this is just an average. In reality, the Earth’s orbit around the Sun is elliptical. This means that it follows the path of an ellipse around the Sun, and not a perfect circle.
When the Earth is at its closest point to the Sun, which astronomers call perihelion, it’s only 147 million km.
And when the Earth is at its furthest point from the Sun, astronomers call this aphelion. At this point, Earth is 152 million km from the Sun.
The Earth, and the Moon orbiting around it, are inclined 5 degrees to the Sun’s axis of rotation. Imagine a disk that slightly rises above the Sun’s plane on one side, and dips down on the other side. It’s for this reason that we don’t get eclipses every two weeks. If the Sun, Earth and Moon were all lined up perfectly on the same plane, there would be many more eclipses. You’d see a solar eclipse one day, and then a lunar eclipse two weeks later.
Since the Earth varies in distance by 5 million km between perihelion and aphelion, what impact does this have on temperature? Not much, actually. Perihelion happens on January 3, and aphelion on July 4. So when the Earth is closest, the northern hemisphere is in Winter, and the southern hemisphere is having Summer.
So, the southern hemisphere does get more Sun – about 6.9% – but its has more oceans, so it can absorb that energy. In the end, it actually all balances out.
The real temperature changes come from the Earth’s axial tilt, which causes the seasons.