Is the Earth closer to the sun in the summer than in the winter?

The closer you are to a heat source, the warmer you are. Earth is a lot hotter in the summer than the winter. The Earth follows an elliptical path so its distance to the sun is not constant. This very logical-sounding line of reasoning leads to a completely wrong conclusion: the Earth is warmer in the summer months because it is closer to the sun.

It is easy to forget that when it is summer in the United States, for example, it is winter in Australia. The Northern and Southern Hemispheres experience their warmest and coldest periods of the year at completely different times. This is the first hint that the conclusion above can’t possibly be right.

The elliptical orbit of the Earth causes a small difference in temperature but the real cause of the seasons is the Earth’s tilt. If you drew an imaginary line between the north and south poles, it would be tilted away from the plane of the Earth’s orbit at a constant 23.5 degrees. During June, July and August, the Northern Hemisphere is tilted toward the sun, resulting in more direct heating and also longer days. In December, January and February, the Northern Hemisphere is tilted away from the sun – sunlight hits the Earth at a more indirect angle and the days are shorter as the sun doesn’t get very high in the sky. In the Southern Hemisphere, the process is obviously just the reverse.