Sunrise, Sunset…Or Not? (810L)

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StepReadTM: Sunrise, Sunset…or Not? (810L)

Sunrise, Sunset…or Not?

The sun is a star. It shines light onto the earth and gives the earth heat. It makes life possible by providing energy and power to living things on Earth.

In most of the world, the sun seems to do the same thing every day. It seems to come up in the east at the beginning of the day and go down in the west at the end of the day. But the sun isn’t really moving. It only seems to move because the earth is turning. Because the earth turns toward the east, the sun seems to come up in the east.

The earth takes 24 hours to turn all the way around. That is the length of one day and night. But at some times of the year there is more daylight than at other times. Summer days may be longer than winter days, for example.

In some places the summer days are a lot longer! The sun stays up in the sky for months without ever going below the horizon. One of those places is Alaska. It is in an area at the top of the earth known as the Arctic Circle. The Arctic Circle is part of Earth’s Northern Hemisphere. For part of the spring and summer, this hemisphere tilts toward the sun, and the north part of Alaska gets tilted so much that the sun doesn’t set there for three months. In those months the sun is known as the midnight sun because it is still in the sky at midnight.

Something very different happens during the fall and winter. At this time the Northern Hemisphere tilts away from the sun. As a result, the sun doesn’t go above the horizon in the north part of Alaska for a little over two months. This period of time is known as polar night. Even though the sun can’t be seen at this time, there is still some light in the sky. People can see well enough to walk around outdoors without using flashlights. 1

StepReadTM: Sunrise, Sunset…or Not? (810L)

Getting through the months of polar night and midnight sun may not be easy for people, but plants and animals have adapted to these months. During the winter in the Arctic Circle, some animals go to sleep for months at a time. Others travel south to where there is more sunlight. And what do animals do during the midnight sun? The 24‐hour sunlight makes things warmer, so mosquitos lay their eggs at this time. They lay their eggs on pools of water that come from melted ice. As a result, the birds that eat these insects have a lot of food. Also, animals that mainly eat plants are able to easily find food at this time of year.

Most people are used to getting some sunlight and some darkness every 24 hours. So are most animals. But living things in places where the sun stays above or below the horizon for months at a time have had to adapt.