[emmelaich]

.. which is defined to be between the tropic of cancer and tropic of capricorn; 23°26′12.2″ north and south of the equator respectively.

[TheSpiceIsLife]

Which is because the earths axial tilt is that angle:

Earth's mean obliquity is currently 23°26′12.2″ (or 23.43672°) and decreasing.

https://en.wikipedia.org/wiki/Axial_tilt