Concept
Epoch (Astronomy)
A reference instant for celestial coordinates.
A fixed moment in time (e.g., J2000.0) used as the reference for positions, motions and orbital elements of celestial bodies.
Overview
A fixed moment in time (e.g., J2000.0) used as the reference for positions, motions and orbital elements of celestial bodies.
See also
Inclined Orbit
An orbit tilted from a reference plane.
Right Ascension
Celestial longitude, measured eastward in hours.
Declination
Celestial latitude, measured in degrees.
The Big Bang
How everything began, 13.8 billion years ago.
Black Holes
Regions where gravity stops light itself.
Dark Matter
The invisible mass holding galaxies together.