When are the equinox, autumnal equinox, winter solstice and summer solstice on the equator?

On the equator, the sun moves from south to north, and it is the vernal equinox when it hits the equator directly; When the sun reaches the north of the equator and the altitude angle is 66 34', it is the summer solstice; When the sun moves from north to south and hits the equator again, it is the autumnal equinox; When the sun reaches the south of the equator and the altitude angle is 66 34', it is the winter solstice.

During the summer solstice, the direct sunlight on the ground reaches the northernmost part of the year, almost directly reaching the Tropic of Cancer. At this time, the daylight time in the northern hemisphere reaches the longest in the whole year. For the Tropic of Cancer and its northern area, the summer solstice is also the highest day of the year at noon. On this day, the northern hemisphere received the most solar radiation, almost twice as much as the southern hemisphere.

It can be simply understood that the vernal equinox and the autumnal equinox are the days when the sun shines directly on the equator. The solstice in summer and the solstice in winter are the days when the sun shines directly on the tropic of Capricorn.