DeclinationThe celestial “latitude”: an object’s angle north (+) or south (−) of the celestial equator, from +90° to −90°. Vega is at +38.8°, Sirius at −16.7°. From a given latitude, declination tells you whether an object is always up, never up, or rises and sets.
Celestial polesThe two points in the sky around which all stars seem to turn: the extension of the Earth’s axis. The north celestial pole lies very close to Polaris; the south pole has no bright star. The pole’s height above the horizon equals your latitude.
EclipticThe Sun’s apparent path among the stars over the year, mirroring the plane of the Earth’s orbit. It is tilted by 23.4° to the celestial equator. The Moon and planets always stay close to it, which helps to recognise them.