Time measurement: Solar Time

Reference systems: Astronomy
Spherical coordinates: 2 angular+1 radial information r=[r;ξ,ζ]
Rectangular coordinates: 3 components information r=[r x
; r y
;r z
]
Spherical coordinates
Radial information
far objects: r∞
spacecraft: r=|r|
origin: Sun ; Earth ⊕; Planet
Celestial Sphere
r
Reference planes
•Planet’s orbit: defined by the planet’s revolutionary angular velocity vector
•Planet’s equator: Defined by the planet’s rotational angular velocity vector
In-plane reference vector
•Inertial e.g. Aries point
•Non-Inertial e.g. Prime meridian