north and south
Equinoxes are when there are twelve hours of daylight and 12 hours of darkness. The autumnal equinox is on September 21st on average, and the vernal equinox is on March 21st on average. You can tell that the seasons have changed and the equinoxes and solstices have occured because the amount of sunlight changes and temperatures also change. Solstices are when there is either the shortest or longest amount of daylight. The summer solstice is when there is the longest amount of daylight. After the summer solstice, days begin to slowly get shorter until the autumnal equinox. The winter solstice is when there is the shortest amount of daylight. After the winter solstice the days get longer until you reach the vernal equinox.
The two equinoxes occur every spring and autumn. The "equinoxes" are two points on the map of the stars. The center of the sun reaches and passes one of them at some moment around March 21, and the other one at some moment around September 22. At those moments, the sun is directly overhead some point on the earth's equator, and every place on earth has roughly equal periods of sun-up and sun-down on that day ... the only two times in the year when these things happen.
Never. The sun never goes past about 23 degrees north or south of the equator.
the equator
The answer is easy - that part of the Earth where the Sun is DIRECTLY OVERHEAD at mid day. However, the answer is also complex because this point moves on a daily basis between the latitudes of the Tropic of Capricorn in the southern hemisphere where it is overhead on or around the 21st December the southern "solstice" and the Tropic of Cancer in the northern hemisphere where it is overhead on or around the 21st June the northern "solstice". This movement is caused by the tilt of the Earth's axis of spin by 23° 26′ 16″ to the plane in which the Earth orbits the Sun.
Twice; both during the sun's summer and winter solstices.
There is no latitude on earth at which the sun would be directly overhead at noon on the equinox and the solstice.
Not always. The sun is directly overhead at the equator at the spring and fall equinoxes.
Respectively, they are the southernmost and northernmost latitudes where the sun may be directly overhead. Each tropic experiences this phenomenon once per year, on the equinoxes of December and June respectively.
At the Tropic of Capricorn.
That would be true of latitudes in the range of roughly 23.5° to 29° both north and south.
The solstices.
If you are at the equator, the SUN will be directly overhead during the equinoxes - around 21 March, and 23 September.
At the equinoxes - around 21 May, and 23 September.
This is due to the amazon being quite close to the Equator, where the sun is almost directly overhead. It is at the March and September Equinoxes that the sun is directly overhead at noon.
The sun is directly overhead at either one of the Tropics on either the June or December Solstice.
At the times of the equinoxes ... a moment on March 21 and another one around September 22.