The Sun's entering rays are perpendicular to the Tropic of Capricorn at 23.5 degrees south latitude during the northern hemisphere winter solstice. The sun's journey above the horizon is lowest north of the equator, and these areas get the shortest day of the year. South of the equator, the sun rises higher, and those regions experience longer days.
The northern hemisphere summer solstice occurs when the Earth is at its farthest distance from the Sun in its orbit, which is also called "perihelion." At this time, the sun is highest in the sky at around 66 degrees north latitude. The southern hemisphere winter solstice happens when the Earth is closest to the Sun, which is called "aphelion." At this time, the sun is furthest from the horizon at around 44 degrees south latitude.
The length of the day varies throughout the year because the Moon causes various tides to rise and fall. The average day is 12 hours long, but it can be as short as 10 hours or as long as 14 hours.
During a lunar eclipse, the Earth's shadow falls on the moon. Because the shadow is dark, we see the moon tonight as if it were completely covered by earthshine—the light from the planet reflected back toward earth by the surface of the moon. Only certain parts of the moon are illuminated during a total lunar eclipse; the rest remains in darkness.
The sun's vertical rays are directly over the Tropic of Capricorn, which is located at 23.5 degrees South latitude. The angle between the horizon and the vertical position of the sun is 90 degrees at the equator and gets smaller as you go north or south of the equator.
At the tropics, the maximum height that the sun reaches above the horizon is 90 degrees all around the clock, no matter what part of the year it is. At other latitudes, the sun will set sometime during the night while you're still awake and then rise again in the morning.
The sun's rays are always angled upward at a horizontal distance from the horizon called the altitude. At the equator, the altitude of the sun is 90 degrees all day every day, but it decreases toward zero at both the north and south poles.
At the North Pole, where the earth's rotation is fastest, the sun makes one complete rotation in 24 hours, even though it doesn't move. At this rate, the sun would drop below the horizon for three minutes before rising again.
At the South Pole, where the earth's rotation is slowest, the sun takes four months to make one full rotation.
The sun's rays fall vertically at the Tropic of Capricorn (23 degrees S), illuminating a bigger region of the Southern Hemisphere. As a result, summer has arrived in the Southern Hemisphere, with longer days and shorter nights. In the Northern Hemisphere, the opposite is true. The Winter Solstice refers to the earth's location at this time of year. At the winter solstice, the north pole is closest to the sun while the south pole is furthest from it.
The day after the winter solstice is the first day of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.
During the night of the winter solstice, the axis of the Earth becomes momentarily aligned such that the northern hemisphere is exposed to the light of the sun and the southern hemisphere is in darkness. This occurs because the tropics are located in the middle of each hemisphere, causing the rotation of the Earth to cause the northern and southern hemispheres to experience daylight and nighttime simultaneously at the equator. Since the path that the sun takes across the sky changes during different seasons, the winter solstice marks the beginning of both the longest and shortest days of the year. At the same time, the polar regions are subjected to coldest temperatures of the year.
In addition to marking the start of spring in the Northern Hemisphere and autumn in the Southern Hemisphere, the winter solstice also influences religion and culture throughout the world.