Zee Media Bureau

Mountain View, California: Earth Day 2013 is being marked in style by search giant Google with an animated doodle adorning its home page on April 22, 2013.

With the change of seasons as the theme, the doodle lets users play and pause a moving `sun` or `moon` on four different images, depicting the four seasons.

Starting from noon on a sunny spring day, the play button on the Google Earth Day 2013 doodle sets the sun in motion westwards and sets. Then the moon rises and the cycle continues through different seasons and phases of the moon.

While in spring there is a little snow on the mountain tops and the flowers and the plants begin to bloom, the temperate climate is replaced by the scorching summer followed by the frozen December when the only sign of life are the fishes in the stream.

Earth Day is held every year to highlight green issues with events being held around the world to demonstrate support for environmental protection.

First ever Earth Day was held in 1970, although the name and concept was pioneered a year earlier by activist John McConnell.

Planting trees in the most common way people support the day.