In the diagram above, note that during the summer months in the northern hemisphere, Earth is tilted toward the sun. Due to that tilt, daylight is longer. When the tilt of Earth’s axis places the sun at it’s highest point above the equator, the summer solstice occurs. It gives us the longest day, or the day with the most amount of daylight. The length of daylight starts gradually decreasing from that point to the winter solstice.

Notice that during the winter months in the northern hemisphere, Earth is tilted away from the sun. Therefore, there is less daylight. When the tilt of Earth places the sun at the lowest point below the equator, the winter solstice occurs. This is the shortest day of the year, and we have the least amount of daylight. The length of daylight starts gradually increasing from that point until the summer solstice occurs.

During the spring and fall at the time of the vernal and autumnal equinoxes, there are two days when the daylight and darkness are of equal length of time. At the vernal equinox, the sun crosses the equator to the north, and at the autumnal equinox, the sun crosses back south over the equator. Living in Alaska, you would find that during the summer months the daylight hours are very long. In fact, it never gets totally dark. The northern hemisphere tilts more towards the sun and receives more direct sunlight. Conversely, in the winter months, the exact opposite occurs. The northern hemisphere tilts away from the sun and receives less direct sunlight.