Aries and SHA on the celestial sphere

On the celestial sphere the stars keep their places, so it helps to hold the stars still and let the Earth turn beneath them. Then a star's SHA and declination do not change at all: SHA is its angle west of the first point of Aries along the celestial equator. What changes is GHA Aries, as the Greenwich meridian turns east under the sky, and that is why the almanac tabulates only Aries hour by hour.

Press Play with "Stars fixed": SHA stays put and GHA Aries runs. Switch to "Earth fixed" and the same sum, GHA star = GHA Aries + SHA, turns the whole sky west instead. Pick "Ecliptic" to see where Aries comes from: the point where the Sun's yearly path crosses the celestial equator going north.