A solar eclipse occurs when the moon gets between Earth and the sun, and the moon casts a shadow over Earth. A solar eclipse can only take place at the phase of new moon, when the moon passes directly between the sun and Earth and its shadows fall upon Earth’s surface. According to NASA, a full solar eclipse occurs every 18 months on average. For any given region, though, a total solar eclipse only happens, on average, once every 375 years. A total eclipse of the sun can only be seen from within what is known as the path of totality, a narrow path the moon’s inner shadow travels as it glides across the Earth. Any point on Earth may experience no more than one total solar eclipse in three to four centuries.