3. In astronomy, ascension is either right or oblique. Right ascension of the sun or of a star, is that degree of the equinoctial, counted from the beginning of Aries, which rises with the sun or star, in a right sphere. Oblique ascension is an arch of the equator, intercepted between the first point of Aries, and that point of the equator which rises together with a star, in an oblique sphere.