Animation
Speed
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X rotation angle
Y rotation angle
Z rotation angle
Reference planes
Julian date JD UTC
Date & time UTC
Date & time at Giza
Sidereal day length
True anomaly
Axial tilt
Ecliptic-Sun equator
Ecliptic-Invariable plane
Longitude of ascending node
Argument of periapsis
Perihelion
Aphelion
Layers
Layer Manager

Astronomy primer

The following astronomy primer is designed to introduce the most basic concepts of orbital mechanics to the reader, so as to provide the names that are applied by astronomers to various orbital elements that are used during the main sections of this work.

The following illustration shows the elliptical orbit of the Earth around the Sun. It is not drawn to scale and is a simplified illustration.

Perihelion is the name that has been given to the point in the orbit where the Earth is at it closest to the Sun at which its angular velocity is at its maximum.

Aphelion is the name that has been given to the point in the orbit where the Earth is at its maximum distance from the Sun and its angular velocity is at its minimum.

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Last edited: 10th July 2019