Every place on Earth receives the same annual amount of heat, but not the same number of hours of sunlight. Both the annual amount of sunlight and the amount of heat received vary over the surface of Earth. Because Earth is a sphere, not all part of the Earth receives the same amount of solar radiation. More solar radiation is received and absorbed near the equator than at the poles. Near the equator, the Sun's rays strike the Earth most directly, while at the poles the rays strike at a steep angle.People who live in the multitudes enjoy maximum daylight on the summer solstice and put up with maximum darkness on the winter solstice. Between the two extremes, sunlight increases or decreases each day, but the rate of change is not steady.

Different parts of Earth receive different amounts of sunlight because of the Earth's rotation. As Earth orbits around the Sun, it also rotates on its axis, which the central line is running through Earth and it turns a complete circle one time per day. The Sun appears higher in the sky during the northern hemisphere summer, moving lower as we move into winter. The larger loop shows how the Sun's position changes rapidly between measurements. At that time of year the Earth is closer to the Sun and therefore travels faster around it. The pattern shows that the number of hours of daylight per day is higher in the summer and lower in the winter. This pattern is caused by the tilt of Earth's axis. At some points in Earth's orbit around the Sun, the tilt causes one hemisphere to lean toward the Sun while the other one is tilted away. People who live in the middle attitudes enjoy maximum daylight on the summer solstice and put up with maximum darkness on the winter solstice. Between the two extremes, sunlight increases or decreases each day, but the rate of change is not steady. Equator receives almost the same amount of sunlight throughout the year and has days and nights of equal duration. This is because the Earth's imaginary axis isn't straight up and down, it is tilted 23.5 degrees. The Earth's movement around this axis causes the change between day and night. During summer in the Northern Hemisphere, daylight hours increase the farther north you go. The Arctic gets very little darkness at night. No matter where in the world you live, do you get the same number of daylight hours over the course of a year? No. The equator actually gets fewer hours of daylight than most other latitudes.

Earth's axis always points in the same direction. Because of this, the part of Earth that receives the most direct rays from the Sun changes as the Earth travels around the Sun. At the equinox, the Sun's rays shine most directly on the equator, and the Northern and Southern Hemispheres get the same amount of Sunlight. No matter where in the world you live, do you get the same number of daylight hours over the course of a year? No. The equator actually gets fewer hours of daylight than most other latitudes. The Equator, at 0° latitude, receives a maximum intensity of the sun's rays all year. As a result, areas near Earth's Equator experience relatively constant sunlight and little solstice variation. The “fixed” tilt means that, during our orbit around our Sun each year, different parts of Earth receive sunlight for different lengths of time. It also means that the angle at which sunlight strikes different parts of Earth's surface changes through the year.Because the Earth is a sphere, the surface gets much more intense sunlight (heat) at the equator than at the poles. During the equinox (the time of year when the amount of daylight and nighttime are approximately equal), the Sun passes directly overhead at noon on the equator.