The zero point of the celestial coordinate known as right ascension (R.A.) is defined to be the
A) intersection of the Milky Way with the celestial equator.
B) point where the Sun crosses the celestial equator moving northward in its path across the sky.
C) point where the Sun crosses the celestial equator moving southward in its path across the sky.
D) intersection of the celestial equator with the projection of Earth's equator on the sky.

Question

Quizplus · Accepted Answer

The zero point of right ascension (R.A.) is defined as the vernal equinox, which is the point where the Sun crosses the celestial equator moving northward in its path across the sky. This occurs around March 20th or 21st each year.

The Zero Point of the Celestial Coordinate Known as Right