agonic line
Noun: * An imaginary line on the Earth's surface connecting all points where the magnetic declination (the angle between true north and magnetic north) is zero. At any location on this line, a compass needle points directly to true geographic north.
The term "agonic line" is used in the specialized fields of geography, cartography, and navigation. It describes a specific, measurable geographic phenomenon.
Examples: * Navigators must account for magnetic declination; their calculations are simplest when they are positioned on the agonic line. * The agonic line is not static and shifts position over time due to changes in the Earth's magnetic field. * On this map, the dashed red curve indicates the current path of the agonic line across North America.
- Historical Shift: The agonic line's position changes over decades and centuries. For example, in the 19th century, it ran through the eastern United States, but it has since shifted westward.
- Isogonic Chart: An "agonic line" is a specific type of isogonic line (a line connecting points of equal magnetic declination). It is the isogonic line where the declination value is zero.
- Isogonic Line (noun): A line on a map connecting points of equal magnetic declination. The agonic line is the zero-declination isogonic line.
- Magnetic Declination (noun): The angle on the horizontal plane between magnetic north (the direction a compass needle points) and true north. This is the variable the agonic line defines as zero.
- Agonic (adjective): Of or relating to an agonic line; having no angle. For example, "an agonic point."
- Zero declination line
- There are no common idioms or phrasal verbs associated with this technical term.
- The word "agonic" derives from the Greek , meaning 'without angle'.
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an imaginary line connecting points on the Earth's surface where the magnetic declination is zero
