What causes the equinox to occur twice a year?

An equinox is an event that takes place in Earth's orbit around the sun. ... The equinoxes and solstices are caused by Earth's tilt on its axis and ceaseless motion in orbit. You can think of an equinox as happening on the imaginary dome of our sky, or as an event that happens in Earth's orbit around the sun.

Explanation:

tilt and orbit of the Earth combine in a way that the axis is inclined away from the sun

Explanation:

We have an equinox twice a year. The Spring and Fall equinox. An equinox occurs when the tilt of the Earth's axis and Earth's orbit around the sun combine in such a way that the axis is inclined away from the sun.

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation: