How are the autumnal equinox and vernal equinox calculated?

The revolution of the earth is counterclockwise, and the arrow from left to right is the autumnal equinox, and vice versa. At this time, the first thing to judge is the summer solstice or the winter solstice. The autumnal equinox follows the summer solstice, and the vernal equinox follows the winter solstice. On the other hand, judging the revolution direction of the earth, it is counterclockwise from above the North Pole and clockwise from above the South Pole.

When the connection between the earth and the sun is perpendicular to the earth axis, it is the vernal equinox or autumnal equinox, and the sun shines directly at the equator. If the direct point of the sun is close to the northern hemisphere, it is the vernal equinox, otherwise it is the autumnal equinox. Seen from north to south, the revolution direction of the earth is counterclockwise.

If you don't know the direction of the earth's revolution, you can only judge whether it is the vernal equinox or the autumnal equinox by other methods, such as the relative positions of the stars such as the earth and the sun. It can also be judged by the direction of the earth's rotation, because the direction of the earth's rotation and revolution is the same.