The Earth is closer to the sun and circles around it in approximately 365 days. In 365 days, 5 hours, 59 minutes, and 16 seconds, the Earth rotates around the sun. The time it takes a planet to circle around the sun defines a year. Years come in three different lengths: 365 days, 366 days, and 24 years. When a year is longer than another, more than one copy of that year will have passed before any single moment on Earth. For example, when a year is divided into 12 months, each month gets half of its year-circle completed. So after two years have passed, six months are done going around the sun; the other six are still to come.
There are several words that are used to describe how long the year is. A solar year is exactly equal to the mean distance between the Earth and the Sun during its orbit around them. This average distance varies over time because the Earth's axis is not fixed in space, but instead wobbles like a spinning top. As a result, the amount of time that we experience as the year changes from season to season, depending on where we are on Earth at the time. Winters and summers last about the same length everywhere on Earth, but fall and spring vary in duration depending on where you are located on Earth. The seasons work together with other factors to influence the rate of evolution on Earth, such as the growth of plants and animals.
The rotation of the Earth around the Sun is referred to as its revolution. One rotation around the Sun takes the Earth 365 days and 6 hours.
A year on Earth is 365.2422 days long, or about 365.25 days. We maintain our calendar in line with the seasons by making most years 365 days long but only around a quarter of all years 366 days long.
The Earth's orbit around the Sun takes 365.24 days. A "day" is defined as the Earth spinning once on its axis. The Earth takes approximately 365.25 days to go around the sun, yet our calendar year is 365 days. To fix this, we add extra days in some years, called leap years.
Years before 1582 did not have any fixed number of days. Instead, they had an average length of 365.25 days.
Years from 1582 until now have been called "normal years". If you calculate the average length of these years, it comes out to 365.25 days. So, every year except 1908 and 1900 was a normal year.
Years from 1900 until 1960 were called "leap years". If you add up the total number of days between 1800-01-01 and 1900-12-31, you get 3,568,000. This means that there were exactly 368 days missing from the year. Since February 29th was a Sunday, they added another day and called it March 1st.
Years since 1961 are called "non-leap years". They too have an average length of 365.25 days, but one more day is added in February because of the leap year rule.
The Earth, like the other planets in the solar system, revolves around the Sun. A year is defined as one complete orbit of the Sun, and it takes Earth 365 days, 5 hours, 48 minutes, and 46 seconds to complete one orbit. The shifting seasons are produced by the tilt of the Earth...
Earth's axis leans with respect to its orbital plane. When the axis points toward the Sun, we experience summer in the northern hemisphere and winter in the southern hemisphere during one annual cycle. When the axis points away from the Sun, we experience summer in the southern hemisphere and winter in the northern hemisphere during the next annual cycle. This motion of the axis relative to the orbital plane is called "precession". Precession is important for long-term changes to the climate, but for daily variations in temperature and other aspects of global warming it is not responsible for all of them.
Precession is caused by the gravitational pull of the Moon and the Sun. As the Earth orbits the Sun, so does the axis of its rotation. The angle between the axis and the orbit varies depending on where on Earth you are at any given time. If you were standing on the North Pole, the axis would be straight up in the sky. If you were standing near the South Pole, the axis would be nearly perpendicular to the ground. The closer the axis is to being vertical, the more upright it is relative to its position around the Earth, and vice versa.