Circle of illumination: An imaginary line that divides the illuminated and unpublished part of the Earth.
▬ The direction of the Earth’s rotation is from west to east. The orbit in which the Earth revolves around the Sun is elliptical. Therefore, on January 3, the distance between the Sun and the Earth decreases relatively, which is called the position of the Perihelion. This distance is 9.15 million miles. In contrast, in the state of Uttarayan, on July 4, the earth moves away from the Sun, it is called Aphelion. This distance is 945 million miles.
▬ Apside Line: The imaginary line joining subauric and subauric passes through the center of the Sun. This is called apside line.
▬ Latitude: This is an imaginary line drawn from west to east on the globe. Which is displayed in degrees. In fact, latitude is the angle that forms at the center of the path between the equator and any other place. The equinoctial line is assumed to be in the state of zero degree. The angular distance moving north from here is called northern latitude and the distance increasing in south is called south latitude. It has poles at its maximum range, which are called 90 ° northern or southern latitudes. All latitude lines are parallel. The distance (area) between two latitudes is known as zone. The distance between two latitudes is 111 km.
▬ The latitude 23 ½ ° north of the equator is considered as the Tropic of Cancer, while the latitude 23 ½ ° to the south is considered the Tropic of Capricorn.
▬ Longitude: It is an imaginary line drawn from north to south on the globe. These lines are not parallel. These lines converge at a point on the north and south pole. The distance between longitudes increases from the poles to the equator and the distance between them at the equator is maximum (111.32) km. The line passing through the Greenwich Observatory is considered a 0 ° longitude. The lines on its left are called the western longitude and the right side lines are the eastern longitudes.
▬ The time of a place is determined on the basis of longitude. The distance between two longitudinal lines is known as Gore.
▬ Zero degree latitude and zero degree longitude cut across the Atlantic Ocean.
▬ Solstice: The boundary of Uttarayan and Dakshinayan of Sun is called Sankranti.
▬ Cancer Solstice: On June 21, the Sun is perpendicular to the Tropic of Cancer (23 ½ °), it is called Cancer Solstice. This day is the largest day in the Northern Hemisphere.
▬ Makar Sankranti: On December 22, the sun is perpendicular to the Capricorn line. It is called Makar Sankranti. This day is the largest day in the Southern Hemisphere.
▬ Equinox: This is the state of the earth, when the rays of the sun are perpendicular to the equator and everywhere are equal day and night.
▬ On 22 September and 21 March, day and night are equal on the whole earth. It is called Autumnal Equinox and Vernal Equinox respectively.
▬ Solar Eclipse: Whenever the moon is not visible due to the moon due to the arrival of the moon between the sun and the earth during the day time, this situation is called solar eclipse. When a part of the sun is hidden, it is called a partial solar eclipse and when the whole sun is hidden for a few moments, it is called a full solar eclipse. The complete solar eclipse always occurs on the New Moon.
▬ Lunar Eclipse: When the Earth comes between the Sun and the Moon, the entire light of the Sun does not fall on the Moon. This is called lunar eclipse. The lunar eclipse always occurs on the night of the full moon. Each full moon does not have a lunar eclipse because there is a difference of 5 ° between the moon and the orbit path of the earth, due to which the moon sometimes passes from the top or bottom of the earth. The lunar eclipse occurs only when the moon passes through the suburbs of the earth maximum three times in a year. Like a solar eclipse, a lunar eclipse can be partial or complete.
▬ Determination of time: When there is a longitude difference, there is a difference of 4 minutes in time. As the earth rotates from west to east. As a result, the time increases on each longitude by 4 minutes on going east and on going west the time decreases by four minutes on each longitude.
▬ International Date Line: The longitude 180 ° is called the International Date Line. In the International Meridian Conference held in Washington in 1884, the International Date Line has been determined on the 180th meridian. This was done so that passengers from different countries would not have trouble due to a difference of 1 day in some places. The international date line passes through the Arctic Sea, the Chuki Sea, the Bering Strait and the Pacific Ocean. Calculating from Greenwich Meridian, areas east of this line (180th metropolis) will be one day ahead or in other words 12 hours ahead of areas west of this line. When a vessel crosses the date line traveling in the western direction, it loses 1 day because the time in this area is running back 12 hours (eg Monday after Sunday). But if the vessel crosses the date line traveling east, then there is a benefit of one day, as if it starts the journey on Monday, on crossing the date line, it will get Wednesday in the new area.
Note: The Wering Strait is located parallel to the International Tidal Line.
▬ Time Zone and Standard Time: The world is divided into 24 time zones. These time zones are divided into Greenwich Mean Time and Standard Time based on an interval of one hour i.e. each zone is equal to 15 °. Greenwich is in the north-west longitude of 0 °, passing through Greenland and the Norwegian Sea and Britain, Spain, Algeria, France, Malé, Burkinafaso, Ghana and the South Atlantic Sea. The standard time of each country is determined by a multiplier of half an hour from Greenwich Mean Time. Standard time is the local time of a voluntarily selected meridian that sets the standard time for a specific region or country. The time of 82.5 degree east longitude in India which passes through Mirzapur near Allahabad is considered as standard time. This time is one hour ahead of Greenwich Mean Time. So when it is 12 noon in Greenwich, it will be 5 pm in India.
▬ Equator: It is the latitude line that passes through the middle surface of the Earth at an equal distance from the North and South Pole. This is the latitude line of zero degree. The northern part of the equator is called the northern hemisphere and the southern part is called the southern hemisphere.
▬ Zone: Each hemisphere is divided into several parts depending on the temperature. These parts are called Kativanya. These are
1. Tropical Zone: 30 ° north and 30 ° south of equator. Here the sun shines on the top twice a year. The weather of this part is always hot.
2. Sub Tropical Zone: An area between 30 and 45 ° northern and southern latitudes, where some months the temperature is high and some months the temperature is low.
3. Temperate Zone: The area between 45 ° to 66 ° northern and southern latitudes. Here the sun never shines above the head, but its rays are tirathi. So the temperature is always low here.
4. Polar Zone: The area between 66 ° to 90 ° where the temperature is very low, due to which there is always snow.