Bringing the Universe to America's Classrooms
(OBS) Illuminating Earth over a Year

Observed Patterns – Explanation 1

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The data you analyzed show that daytime is longer in summer months than in winter months and that the northern and southern hemispheres experience opposite seasons. Using what you know about the Earth–Sun relationship, explore two possible explanations for those patterns.

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Distance from the Sun 
Look at this diagram of Earth’s orbit. This view of the orbit is as if you were looking down at Earth and the Sun. Notice the shape of the orbit. Click to view a larger version.

Earth’s orbit diagram
Earth’s orbit is shown from an overhead view. The orbital path appears almost circular, with the Sun near the middle of the orbit. At about July 5, Earth is 94.5 million miles away. At about January 4, Earth is 91.4 million miles away.

Take Notes

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Think about Earth’s orbit around the Sun. Some people think that Earth’s distance from the Sun might explain the observed daylight patterns in both hemispheres. Provide evidence to explain why you agree or do not agree with this idea.

Learn More

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Earth’s orbit is close to (but not exactly) a perfect circle, with the Sun directly in the middle. The difference in the distance between Earth and the Sun throughout the year is not enough to affect weather. Around January, Earth is slightly closer to the Sun. Around July, it is slightly farther from the Sun.

Take Notes

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Could Earth’s distance from the Sun really explain the patterns of seasons and why summer and winter happen at the same time in New York and Australia? Provide evidence from the orbit diagram and the text to support your answer.

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