Key Idea: As the earth moves around the sun over the course of a year, the orientation of earth’s axis with respect to the sun changes. This shift causes the length of daytime and nighttime at a place to change and the amount of energy the place receives from the sun to change over the course of a year.

Students are expected to know that:

  1. As the earth moves around the sun between late December and late June and the angle between the center of the sun, center of the earth, and the north pole gradually becomes smaller, places in the northern hemisphere gradually spend more time each day in sunlight, and places in the southern hemisphere gradually spend less time in sunlight. Between late June and late December as the angle between the center of the sun, center of the earth, and the north pole gradually becomes larger, places in the northern hemisphere gradually spend less time each day in sunlight, and places in the southern hemisphere gradually spend more time in sunlight.
  2. The farther a place is north or south of the equator, the more the length of daytime changes over the course of a year such that places near the north and south poles can experience as much as 24 hours of daytime and and as little as 0 hrs of daytime at different times of the year. At the equator, however, the length of daytime does not change over the course of a year because the equator is a circumference of the earth, so half of it is illuminated at any given time.
  3. The longer sunlight of a given intensity reaches a place on the surface of the earth, the more energy is transferred to that place.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

CLM090

No two places on the surface of the earth ever receive the same number of hours of daylight on the same day (AAAS Project 2061, n.d.).

37%

42%

CLM086

The number of hours of daylight a place receives changes over the course of the year because of changes in the how far the earth is from the sun (AAAS Project 2061, n.d.).

28%

37%

CLM088

There is one day each year when every place in the northern hemisphere receives 12 hours of daylight and 12 hours of darkness, and there is another day each year when every place in the southern hemisphere receives 12 hours of daylight and 12 hours of darkness (AAAS Project 2061, n.d.).

31%

29%

CLM087

There is never a day when every place on earth receives 12 hours of daylight and 12 hours of darkness (AAAS Project 2061, n.d.).

26%

27%

CLM085

The number of hours of daylight a place receives changes over the course of a year because of changes in how fast the earth turns on its axis (AAAS Project 2061, n.d.).

27%

22%

CLM074

Places at the same latitude receive different amounts of daylight (AAAS project 2061, n.d.).

20%

19%

CLM089

There is never a time when places near the south pole receive a greater number of hours of daylight than anywhere else on earth (AAAS Project 2061, n.d.).

20%

16%

CLM084

There is never a time when the south pole receives a greater number of hours of daylight than anywhere else on earth (AAAS Project 2061, n.d.).

19%

16%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.