As the Sun moves counterclockwise relative to the fixed stars, which coordinate is continuously increasing?

• A. Right Ascension
• B. Sidereal Time
• C. Declination
• D. Azimuth

Answer: (A)

As the Sun appears to travel eastward around the sky, its position on the celestial sphere moves along the ecliptic in a consistent direction. Right ascension is the coordinate that measures angular distance eastward along the celestial equator, defined so that the vernal equinox has RA 0h and values increase toward the east up to 24h. Since the Sun’s annual path is essentially an eastward progression relative to the distant stars, its right ascension increases continuously over the year (wrapping back to 0h after 24h).

Declination, the north–south component, changes with the seasons as the Sun’s path tilts above and below the celestial equator, so it does not increase monotonically. Azimuth is a local horizon-based direction that varies with your observing location and time of day, not a fixed coordinate of the Sun’s position on the sky. Sidereal time is a time factor tied to Earth's rotation and the fixed stars, not the Sun’s position itself. Therefore, the coordinate that keeps increasing as the Sun moves CCW relative to the stars is right ascension.