### Definition Of apsis

**noun**

either of two points on the orbit of a planet or satellite that are nearest to or furthest from the body around which it moves.

In particular there was, according to Aryabhata I, a basic period of 4320000 years called a mahayuga and it was assumed that the sun, the moon, their apsis and node, and the planets reached perfect conjunctions after this period.

### Example Of apsis

At time II the line of **apsides** has turned through 90 degrees and we get a symmetric eclipse, indistinguishable from a circular orbit.

Because of gravitational disturbances by the other planets, the shape and orientation of the orbit are not fixed, and the **apsides** slowly move with respect to a fixed frame of reference.

Both the **apsidal** axis and the moon's nodal axis rotate.

By latus component we mean the component of the orbital velocity in the direction perpendicular to the **apsidal** axis of the orbit.

For the moon, the line of **apsides** completes one revolution around the sky in a period of 8.85 years.

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