Why does the sun always rise in the east and set in the west ?

Why does the Sun rise in the east?

As the Earth moves in its orbit round the Sun, it also spins at about 1600 km/h (1000 mph) at the equator. It took many centuries for astronomers to make that point. In about 350 bc, the Greek philosopher Heracleides first advanced the theory that the Earth turned, not the sky. Nobody believed him.

In the 1620s, Galileo Galilei noticed that spots on the Sun changed their position. He deduced that the Sun was actually revolving, and argued that in his view the Earth did the same. In 1633, the Catholic Church demanded a public renunciation. Galileo was forced to declare that the Earth was fixed. How, after all, could we walk on Earth if it were constantly spinning like a top? In 1992, after a long inquiry, the Church finally acknowledged its error.

In time, other astronomers showed indisputably that the Earth and other planets revolve but at different speeds.

In 1851, the matter was proved without doubt. In a dramatic demonstration, French physicist Jean Foucault suspended a long pendulum from the ceiling of the Pantheon in Paris and set it swinging. As it swung, its tip left a mark in a patch of sand underneath. A heavy weight tends to swing in the same direction, but hour by hour the position of the mark changed. Beneath the pendulum the Earth was turning as all visitors could see.

All planets except Venus rotate from west to east, so it is always the east that gets the first glimpse of the Sun. That never changes, no matter where the Sun is in the zodiac or where the Earth is in relation to the Sun.

You can test that for yourself with a table lamp and a globe of the Earth, if you have one. If not, use a ball. Switch on the lamp and pretend that it is the Sun, and that the globe or ball is the Earth (even though the Sun is big enough to swallow up 1.3 million Earths). On the ball, draw America, Europe/Asia or Australia, whichever is most familiar to you. Turn your globe or ball slowly from west to east. If you are looking from above, that is anticlockwise. As you will see, the Sun’s light always falls first on a continent’s eastern side, and travels during the day gradually to the west. One complete turn of the ball represents a day in the life of our planet.