Hours measured along the celestial equator, starting from the March equinox (intersection of the ecliptic with the celestial equator). The units of right ascension are hours, since the celestial equator is divided into 24 equal portions. Each hour of Right Ascension is divided into 60 equal minutes. By convention, the starting point, or 0 hours of right ascension, is a point on the celestial equator called the vernal or March equinox. Right Ascension is also measured northward from the east point of the equator to the vertical circle (90?° to the equator) that runs through the planet or point to be measured.