Earth Day is observed every year on April 22, when more than one billion people across the world mark the event by showing support for environmental protection.

Festivals, rallies and outdoor events are held in nearly 200 countries – often, with the support of A-list celebrities and political leaders.

Earth Day marks the anniversary of the birth of the modern environmental movement in 1970 and aims to encourage people across the world to be more environmentally friendly.

This might mean increasing the amount they recycle, volunteering for a local green project or installing solar panels in their home.

The very first event for Earth Day, which was held in America following a devastating oil spill, is credited as the beginning of the modern environmental movement. The idea for a national day to focus on the environment came to Earth Day founder Gaylord Nelson, then a Senator from Wisconsin, after witnessing the ravages of the 1969 massive oil spill in Santa Barbara, California.

April 22, falling between Spring Break and Final Exams, was selected as the date to celebrate Earth Day.

The height of counterculture in the US, 1970 brought the death of Jimi Hendrix, the last Beatles album, and Simon & Garfunkel’s Bridge Over Troubled Water. War raged in Vietnam and students nationwide overwhelmingly opposed it.

Since its launch, Earth Day has been supported by an array of famous people like Leonardo DiCaprio and Emma Watson.

Now it is coordinated globally by the non-profit Earth Day Network, which describes it as “the largest secular holiday in the world”.

Each year, festivals, parades and rallies are held in at least 192 countries to demonstrate support for environmental protection.

Earth Day has its own flag, which was created by peace activist John McConnell and features a picture of the world on it.

It also has its own anthems – one of which is performed to the tune of Beethoven’s Ode To Joy, but with lyrics about protecting the planet.

In 2017, more than one billion people are expected to celebrate Earth Day. Earth Day 2017’s Campaign is Environmental & Climate Literacy.