*the grid formed by lines of latitude/longitude is known as a “graticule”
*a ‘graticule’ on the Earth as a ‘sphere’ or an ‘ellipsoid’*
The lines from pole to pole are lines of constant longitude, or meridians.
The circles parallel to the Equator are circles of constant latitude, or parallels.
The graticule shows the latitude and longitude of points on the surface
.
In this example, meridians are spaced at 6° intervals and parallels at 4° intervals
.
-as of [30 MARCH 2024]–
.
.
.
.
/ˈlɒndʒᵻtjuːd/
OR
/ˈlɒndʒᵻtuːd/
.
australian + british —>
/ˈlɒŋɡᵻtjuːd/
.
-“longitude” is a ‘geographic coordinate’ that specifies the ‘east-west’ position of a ‘point’ on the earth’s ‘surface’-
.
(it is an angular measurement, usually expressed in degrees and denoted by the greek letter ‘lambda’ (λ))
(‘meridians’ (lines running from the ‘north pole’ to the ‘south pole’) connect points with the same longitude)
(by convention, one of these, the “prime meridian”, which passes through the ‘royal observatory’, ‘Greenwich’, ‘England’, was allocated the position of zero degrees longitude)
(the longitude of other places is measured as the angle east or west from the ‘Prime Meridian’, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward)
(specifically, it is the angle between a plane containing the ‘prime meridian’ and a plane containing the ‘north pole’, ‘south pole’, and the location in question)
(this forms a right-handed coordinate system with the z axis (‘right hand thumb’) pointing from the earth’s center toward the ‘north pole’ and the x axis (right hand index finger) extending from earth’s center through the equator at the ‘prime meridian’)
(a location’s north–south position along a meridian is given by its latitude, which is approximately the angle between the local vertical and the plane of the ‘equator’)
(if the earth were perfectly spherical and homogeneous, then the longitude at a point would be equal to the angle between a ‘vertical north–south plane’ through that point and the ‘plane’ of the ‘greenwich meridian’)
(everywhere on earth the ‘vertical north–south plane’ would contain the earth’s axis)
(but the earth is not homogeneous, and has mountains—which have gravity and so can shift the vertical plane away from the earth’s axis)
(the vertical north–south plane still intersects the plane of the ‘greenwich meridian’ at some angle; that angle is the astronomical longitude, calculated from star observations)
.
(the ‘longitude’ shown on [‘maps’ / ‘GPS devices’] is the angle between the ‘greenwich plane’ + a “(not-quite)-vertical plane” through the ‘point’*
.
(the “(not-quite)-vertical plane” is perpendicular to the ‘surface’ of the ‘spheroid’ chosen to approximate the earth’s ‘sea-level surface’, rather than perpendicular to the ‘sea-level surface’ itself)
.
.
*👨🔬🕵️♀️🙇♀️*SKETCHES*🙇♂️👩🔬🕵️♂️*
.
.
.
.
.
💕💝💖💓🖤💙🖤💙🖤💙🖤❤️💚💛🧡❣️💞💔💘❣️🧡💛💚❤️🖤💜🖤💙🖤💙🖤💗💖💝💘
.
.
*🌈✨ *TABLE OF CONTENTS* ✨🌷*
.
.
🔥🔥🔥🔥🔥🔥*we won the war* 🔥🔥🔥🔥🔥🔥