Concept
Proper Motion
A star's drift across the sky over years.
The angular velocity of a star across the celestial sphere relative to the background of more distant stars.
Overview
The angular velocity of a star across the celestial sphere relative to the background of more distant stars.
See also
Planetary Migration
Planets drifting inward or outward over time.
Ecliptic
The Sun's apparent annual path across the sky.
Colour Index
A star's colour expressed numerically.
Bolometric Magnitude
Brightness across all wavelengths.
The Big Bang
How everything began, 13.8 billion years ago.
Black Holes
Regions where gravity stops light itself.