The need to accurately determine the location on the earth's surface of one's own and surrounding objects has become especially relevant for a person with the beginning of active exploration of the planet.
Geographic coordinates - latitude and longitude - are determined by the intersection point of two imaginary lines - the parallel and the meridian. The longest parallel from which the latitude starts is the equator.
Origin of the name
An imaginary line, which is formed on the surface of the globe by points located at the same distance from both poles, divides the planet into two hemispheres, two hemispheres. The word for the name of such a border has ancient roots. The Latin aequator, equalizer, is derived from the verb aequō, to equalize. The "equator" entered the international practice from the German language, from Äquator.
This word has a more general meaning. In geometry, a three-dimensional body, which has both an axis and a plane of symmetry mutually perpendicular, has its own equator, its longest parallel - the intersection of the surface of the given body with the plane of symmetry. In astronomy, the celestial equator, magneticequator of a planet or star.
Earth is a geoid
The belief that the Earth has the shape of a flat disk was questioned only by ancient Greek scientists. By the end of the 19th century, it became clear that the shape of our planet is not just an ideal ball, but a special body of revolution - the geoid, the surface of which is influenced by many factors - from gravity to the "cosmic wind". Two points of the geoid are determined by its axis of rotation - these are the North and South Poles. At an equal distance from them is the longest parallel on Earth, the earth's "waist" - the equator.
But the geoid does not accurately, but only approximately describes the shape of the planet. Such it would be in the absence of mountains and depressions, if there were only a calm, undisturbed surface of the oceans. This level plays an important role in navigation and geodesy - it is used to report vertical marks for various technical and engineering objects.
Equator length
It is also possible to understand which parallel is the longest by the specific values of the geometric measurements of the geoid. The radius of the equator, as a circle "drawn" on the surface of the Earth, is equal to the radius of the planet. Precise measurements show that this parameter differs in different parts of the planet - the polar radius is 21.3 km less than the equatorial one. Average value - 6371 km
According to the circumference formula - 2πR - you can calculate the length of the equator. Different geophysical standards define figures with a difference of about 3 m, on average - 40075 km. Circumference along the meridian - 40007 km, which proves the special geometric qualities of the geoid.
Zero latitude
The coordinate grid that covers the globe - a visual model of the globe - is formed by 360 meridians connecting two poles, and 180 lines parallel to the equator, distributed 90 pieces to the poles, on both sides of it. Since 1884, the meridian drawn through the Greenwich Observatory, located in the southeast of the English capital, is considered to be the beginning of the longitude count since 1884. The longest parallel dividing the globe into the northern and southern hemispheres is the origin of latitude.
Coordinates are angular values, measured in degrees. Longitude is the angle between the plane passing through the zero - Greenwich - meridian and the one indicated by the line connecting the earth's poles and drawn through this point. To the east of Greenwich to 180° longitude is called east and is considered positive, to the west it has negative values and is called west.
Points equidistant from the poles form the equatorial plane. The radius drawn from the center of the globe through a given point on its surface forms an angle with this plane, the magnitude of which is the latitude. The longest parallel has zero latitude. To the north of the equator, this angle is considered positive - from 0° to 90°, to the south - negative.
Signs and rituals
The equator is just an illusory border between the two hemispheres, but it has always stirred the human imagination. It is customary for sailors from different countries to observe special rituals when crossingzero latitude, especially for those who do it for the first time. Where the equator passes inhabited places, special signs and structures are invariably erected to make the conditional line real. A rare tourist will miss the opportunity to stand with one foot in the Southern and the other in the Northern Hemisphere. After that, it is impossible to forget what the longest parallel of the globe is called.
But the equatorial zones of the Earth have other unique characteristics that give them a special value. The gravitational pull here is slightly less than at other latitudes, and the rotational momentum of the globe is greater. This makes it possible to significantly save rocket fuel for launching spacecraft into orbit. It is no coincidence that it is in equatorial French Guiana, on the South American coast, that the most effective launch space complex, the Kourou cosmodrome, is located.
