# Celestial Sphere

An imaginary sphere of infinite radius centered on the Earth and poles aligned with the poles of the Earth.

A point on the celestial sphere is really only a direction in space. Parallel lines meet the celestial sphere at the same point.

### Antisolar Point

The point on the celestial sphere 180° from the sun.

### Apparent Position

The position on the celestial sphere at which a heavenly body would be seen from the centre of the earth at a particular time.

### Astrometric Position

The position of a heavenly body (or space vehicle) on the celestial sphere corrected for aberration but not for planetary aberration.

**See also: **Nadir.

**Subjects: ** Astronomy