Astronomers say that the sun will align with the Kaaba at the Grand Mosque on Thursday at 1418 hours PST. The disc of the sun will be positioned immediately over the Kaaba and it will lose its shadow for a brief time, said Majed Abu Zahra, head of the Jeddah Astronomical Society. Astronomers said the celestial phenomenon called “zero shadow” occurs twice every year at the Grand Mosque because of its location between the Equator and the Tropic of Cancer. Due to the tilt of the earth’s axis, the sun travels at 23.5 degrees north and south of the celestial equator. The sun falls directly overhead on places lying over the equator during equinox. Abu Zahra said people can determine the exact direction of the Kaaba by placing a wooden stick vertically in the ground; the direction of the Qibla will be the exact opposite to the stick’s shadow.