Glossary R

Right Ascension (α). In astronomy, right ascension is the angular distance of a celestial object in an eastward direction parallel to the celestial equator. Along with declination it is one of the two coordinates of the equatorial coordinate system. It is measured from the position of the Sun at the northward equinox. It can be expressed in degrees but is usually measured in hours, minutes and seconds, where 1 hour = 15° or 1° = 4 minutes.

Rising.

Roman Calendar.

Roman Era. A conventional period of Greek history which runs from the defeat of Corinth by the Romans in 146 BCE, and their subsequent domination of Greece, until the fall of the western Roman Empire in 476 CE. It followed the Hellenistic Era (323 – 146 BCE). The end of the Roman Era effectively marks the end of Antiquity.