Why do total sudden eclipses not happen every month when there was in new moon?
Total solar eclipses do not occur every month during the new moon because the Earth and the Moon's orbits are not perfectly aligned.
During a new moon, the Moon is situated between the Earth and the Sun. However, the Moon's orbit is slightly inclined relative to the Earth's orbit around the Sun, resulting in most new moons passing above or below the Sun from the perspective of Earth. This misalignment causes the Moon's shadow to usually miss the Earth.
Total solar eclipses occur when the Moon's orbit brings it directly between the Earth and the Sun, and the apparent size of the Moon completely covers the Sun's disk. This alignment, known as syzygy, is rare due to the slight inclination of the Moon's orbit.
Although total solar eclipses occur about once every 18 months on average, they are visible from any single location on Earth only once every few centuries. Other types of solar eclipses, such as partial or annular eclipses, are more common and occur when the alignment is not perfect.