Answer: During the months of March and September
Explanation: Hemisphere is a combination of two words; hemi meaning half and sphere referring to the earth which is a spherical celestial body.
The Hemisphere of the Earth is divided into two; Northern and Southern Hemisphere.
The Northern Hemisphere refers to the Hemisphere above the equator and Southern Hemisphere refers to the Hemisphere below the equator.
The earth completes it's revolution about the sun in 365 days. For the first 365 days, the Northern Hemisphere receives more amount of the sun energy while for the second half, the Southern Hemisphere received more amount of the sun's energy.
During equinox however, both the Northern and the Southern Hemisphere receive the same amount of the sun's energy due to the zero tilt (rotation) of the Earth's axis.
The equinox in the Northern Hemisphere is referred to as Spring equinox while that of the Southern Hemisphere is referred to as Autumnal equinox.
These equinoxes occurs in the months of March and September every year.