In astronomy it is called the axial tilt (also called obliquity) and sometimes just called the imaginary axis.
axis - An imaginary line that passes through earths center and its north and south poles.
The imaginary line that passes through the Earth's center and the North and South Poles is called the Earth's axis. It is an important reference point for understanding the Earth's rotation and tilt.
Tropic of Capricorn
a latitude line
The Tropic of Capricorn passes through Botswana.
An imaginary line which passes through the poles of the planet.
the tropic of Capricorn
A lunar eclipse occurs when the full moon passes through the Earth's shadow.
Tropic of Cancer
Tropic of cancer.
The imaginary line about which an object spins is called the axis of rotation. It is an imaginary line that passes through the center of mass of the object around which it rotates. The object rotates around this axis resulting in circular motion.
The imaginary line at zero degrees longitude is called the Prime Meridian. It is the starting point for measuring east and west and passes through Greenwich, London.