They often find it difficult to comprehend distances in the order of their own country and consequently larger distances like those involved with the solar system are often unimaginable for them.
In addition, students observe motion from their own point of reference. In order to understand the motion of the sun and Earth they must imagine a different point of reference.
This can make ideas in this area very challenging for students to grasp. The views held by students about the shape of the Earth are varied and often unique to the individual. Even though students can often articulate that the Earth is a sphere, upon further investigation they often believe in fact that the Earth is how they perceive it, flat. Some children view the Earth as round or circular as opposed to spherical see diagram 1 below.
Another common view is of the Earth as flat and that it and the air form a sphere see diagram 2 below. Students can often represent the Earth as a sphere or circle on the plane of the paper but they still perceive the person on the top of the sphere as the upright person see diagram 3 below.
These views are also evident in and related to the focus idea Forces without contact. However, viewed from the southern polar region, it appears to be rotating clockwise. The Earth rotates once in about 24 hours with respect to the Sun and once every 23 hours 56 minutes and 4 seconds with respect to the stars.
Instead, at any given time of the year, one hemisphere is pointed slightly more towards the Sun, leaving the other pointed away. During this time, one hemisphere will be experiencing warmer temperatures and longer days while the other will experience colder temperatures and longer nights. Of course, since the Earth is rotating around the Sun and not just on its axis, this process is reversed during the course of a year.
Every six months, the Earth undergoes a half orbit and changes positions to the other side of the Sun, allowing the other hemisphere to experience longer days and warmer temperatures.
Consequently, in extreme places like the North and South pole, daylight or nighttime can last for days. Those times of the year when the northern and southern hemispheres experience their longest days and nights are called solstices, which occur twice a year for the northern and southern hemispheres. Why does Earth's day length change during the year?
Every location on Earth experiences an average of 12 hours of light per day but the actual number of hours of daylight on any particular day of the year varies from place to place. Locations around Earth's equator only receive about 12 hours of light each day.
In contrast, the north pole receives 24 hours of daylight for a few months in the summer and total darkness for months in the winter. These two annual times of light and dark are separated by a long sunrise and a long sunset. Earth rotates on its axis; this causes us to experience day and night.
But Earth's axis is tilted As Earth orbits our Sun, the axis points toward the same location in space — almost directly toward Polaris, the North Star. This means that during Earth's movement around our Sun each year, our polar regions spend loooooooong periods pointed toward our Sun in the summer for example, July in the northern hemisphere, or December in the southern hemisphere and long periods pointed away from our Sun during the winter.
At latitudes greater than Because of this tilt and Earth's movement around our Sun, there is a time when Earth's north pole is tilting This is the summer solstice, the first day of the northern hemisphere summer and the longest day of the year in the northern hemisphere. On December 21 or 22, Earth's north pole is tilting The side facing the sun is bathed in light and heat—we call this daytime.
The side facing away is cooler and darker, and experiences night. Because the Earth is constantly spinning, the line between day and night is always moving around the planet.
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