The rotation of the Earth on its axis causes the variation between day and night. The durations of days and nights vary depending on where you are on Earth and the season. In addition, the tilt of the Earth's axis and its route around the sun influence daylight hours. The result is that there are two different lengths of night in any given month.
Day and night lengths vary little from place to place on the surface of the planet. Day is always longer than night, and their difference varies little from region to region or even within small regions. For example, a person living near a large city such as New York City will experience almost exactly 12 hours of daylight and 12 hours of darkness each day, regardless of the time of year. By contrast, someone living in a rural area far from any town will have considerably longer nights in winter and shorter days in summer.
Daylight hours are increasing in most parts of the world due to an increase in the amount of sunlight at high latitudes and altitudes. At these locations, daylight hours used to be short in the spring and fall but have been getting longer over the past few decades.
However, at low latitudes and lower elevations daytime temperatures are rising more quickly than expected, which means that people are staying out later in the evening than before. This leads to less time spent sleeping and more time spent working or playing activities that require light.
The day/night cycle would be considerably different, if not non-existent, if the Earth did not revolve as it does. The axial tilt results in part of the surface of the earth being constantly illuminated while another part is perpetually dark.
As the Earth rotates, so too do all the planets, including our own. But because the planet's orbit is more or less circular, each point on a planet orbits the central star once every 24 hours, whether that point is north or south of the equator. The angle between one point and the next varies only slightly, which is why all points on Earth experience both sunrise and sunset every day.
Our own moon also affects how many days and nights there are, but that's another story...
Day and night come into existence when the sun goes down and doesn't rise again at the same time the next day. The interval of time during which this occurs is called an "hour". At some times of the year, such as in summer, hours last for a long time, at other times, such as in winter, they seem to pass very quickly. That's because the length of an hour depends on where you are on Earth.
The rotation of the earth causes the difference between day and night. And the changing of the seasons is driven by the earth's orbit around the sun. In the spring and autumn, the day and night share the same time period (12 hours each season), however in the summer, the day is longer than the night. In the winter, the day is shorter than the night.
These are just some of the many things you should know about Earth! As you can see, it is a very interesting planet that we call home. It has been known to surprise us with its behavior, but it always turns out better than expected. I hope you have enjoyed this video about why Earth matters. If you want to learn more about our planet, check out these links:
The tilt of the Earth's rotation axis in respect to its orbit around the Sun causes the change from day to night. If the axis was perfectly perpendicular to the plane of the Earth's orbit, we would have 24 hours of daylight and 12 hours of darkness at the equator (where the axis is pointing). But because the Earth spins on its axis, the northern hemisphere experiences a swing from day to night and vice versa. The period of this swing is called a day. At the poles it is 24 days, but at the equator it only amounts to 23 or 22 depending on which side of the equator you are on.
At the moment of solar noon, the north pole is facing towards the sun, while the south pole is looking away. This means that at mid-day at the poles there is no shadow at all, while at the equator you get half of one degree. Because the axis of rotation of the Earth is not exactly parallel with its orbital path, but is tilted by about 23.5 degrees, at any given time there are areas on our planet that are illuminated by sunlight and others that are in darkness. These regions rotate along with the Earth, so if they were flat plates they would appear to move across the sky as the Earth rotates.
What is the origin of day and night? The rotation of the Earth on its axis causes day and night. On the side of the Earth that faces the sun, it is day. On the side of the Earth that faces away from the sun, it is darkness. The moon also has an influence on how long each day is by changing when the Earth's shadow falls across it. When the moon is full, it blocks out all of the Earth's shadow, so there is no eclipse.
Where does the Earth go during a lunar eclipse? During a total lunar eclipse, the Earth is completely covered by the moon's shadow. So everywhere on Earth's surface, the sun is blocked out by the moon - including right over the center of Earth. Only around half of the moon is in darkness - the other half is still exposed to sunlight! Because of this, only the far side of the Earth is visible from places such as Australia where it is daytime all the time. People living there see the moon during a total lunar eclipse.
People who live near the equator see all parts of the moon during a total lunar eclipse. It's just like seeing the whole moon all the time anywhere else on Earth. A total lunar eclipse can be seen from pretty much everywhere on Earth apart from North America.
Why don't we ever see a lunar eclipse? As the moon orbits the Earth, it passes through the atmosphere every few days.
The number and pace of changes in daylight hours vary depending on a location's latitude. The most dramatic and fast shifts occur farthest from the equator (at the poles). The tilt of the Earth's axis as it spins and circles the sun generates these seasonal fluctuations in daylight hours. As we move toward the equator, day length remains fairly constant throughout the year.
At the two poles, night lasts for nearly half the year. At the equator, however, where day and night are equal in length, there is no such thing as full or partial darkness. The only difference between midday and midnight is that at mid-summer, when the days are longest, the sun is lower in the sky then at either winter solstice or summer solstice, so there is less direct sunlight. At mid-winter, when the days are shortest, the sun is directly above the horizon all day long.
As you travel south of the equator, day length decreases and night falls earlier in the year. By the time you reach the tropics, day length has decreased by about half and night falls around noon every day. At the equator, daytime temperatures can reach 120 degrees F; at the poles, nighttime temperatures plummet to -180 degrees F.
During a solar eclipse, the moon blocks out part of the sun, causing twilight to fall quickly.