The Earth’s axis slowly spins like that of a top. Also, the ellipse forming the Earth’s orbit very gradually rotates, making the shape traced out by the earth around the Sun over many years form a daisy. Due to both types of precession, astronomers have identified three types of years: sidereal year, (365.256 days) which is one orbit with respect to distant stars, anomalistic year (365.259 days), which is the length of time it takes for the Earth to travel from its closest point (perihelion) to its farthest point from the Sun (aphelion) and back again, and tropical year (365.242 days) the duration from one spring equinox to the next.
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Adds Precession to Rotation
The Earth’s axis slowly spins like that of a top. Also, the ellipse forming the Earth’s orbit very gradually rotates, making the shape traced out by the earth around the Sun over many years form a daisy. Due to both types of precession, astronomers have identified three types of years: sidereal year, (365.256 days) which is one orbit with respect to distant stars, anomalistic year (365.259 days), which is the length of time it takes for the Earth to travel from its closest point (perihelion) to its farthest point from the Sun (aphelion) and back again, and tropical year (365.242 days) the duration from one spring equinox to the next.