Question

why do eclipse not occur on every full moon night and new moon day​

Answer 1

Answer:

                      It's true that the moon goes around Earth every month, but it doesn't always get in Earth's shadow. The moon's path around Earth is tilted compared to Earth's orbit around the sun. The moon can be behind Earth but still get hit by light from the sun. This is why we don't get a lunar eclipse every month and perfect alignment for an eclipse doesn't occur at every full moon.

Answer 2

Eclipses occur when either the Earth comes in between the sun and the moon (lunar eclipse) or the moon comes in between the Earth and the sun (solar eclipse). The Earth takes around 1 year to orbit the sun and the moon takes around 1 month to orbit the Earth but still lunar and solar eclipses don't occur every month because the orbit of the moon and the around the Earth and that of the Earth around the sun aren't always in the same plane instead they keep shifting with respect to each other and when they become coplanar then only an eclipse can occur so usually 2 to 4 solar eclipses and 0 to 3 lunar eclipses occur every year and at most there are only 4 solar and 3 lunar eclipses in a year.

:-)