The total or partial blocking of one celestial body by another
A bright line in a spectrum caused by emission of light. Each chemical element emits and absorbs radiated energy at specific wavelengths. The collection of emission lines in a spectrum corresponds to the chemical elements contained in a celestial object.
Tables of data which list the positions of the Sun, Moon, planets and other Solar System objects
The minimum velocity required for an object to escape the gravity of a massive object.
A planet that orbits a star - other than the sun