Today is the day to think about the planet. Some say that today is the largest secular holiday in the world.
Earth Day, celebrated every year on 22 April, is a day to reflect on the measures all of us can take to protect the environment and life on earth.
And this year's Earth Day is significantly more important because world leaders are gathering at the United Nations on Friday to sign the Paris climate deal and get the ball rolling on a quick entry into force to start beating back global warming.
The first Earth Day was celebrated as a national holiday in the United States in 1970. According to Earth Day Network, Gaylord Nelson — Earth Day founder and US Senator from Wisconsin — announced his idea for a "national teach-in on the environment" after witnessing the destruction caused by the 1969 oil spill in Santa Barbara, California.
22 April was the day selected for the event because it fell between spring break and final exams in the US. Twenty-two million Americans took part in the first Earth Day.
The first global Earth Day was celebrated in 1990.
Around 220 million people in 141 countries participated in the event which gave a "huge boost to recycling efforts worldwide and helped pave the way for the 1992 United Nations Earth Summit in Rio de Janeiro."
Today, the day is organised by the Earth Day Network, which is "the world’s largest recruiter to the environmental movement, working with more than 50,000 partners in 196 countries to build environmental democracy."
Since its launch, Earth Day has also been supported by celebrities like Leonardo DiCaprio and Emma Watson, according to Mirror.
The day has its own flag and even has its own anthem, performed to the tune of Beethoven's Ode To Joy.
For this year's Earth Day, Google has created a special map to point out the location of several events taking place across the planet to celebrate the day.
Europe on Friday is also going to launch satellites to track environmental damage to Earth, reported AFP. Setting off on a Russian Soyuz rocket will be Sentinel-1B with its Earth surveillance radar, and Microscope, a French-built orbiter seeking to poke a hole in Einstein's theory of general relativity.
They will be hoisted from Europe's launch pad in Kourou, French Guiana, at 9 pm GMT (1.30 am IST on Saturday) on Friday.
But the most important event on this year's Earth Day will undoubtedly be the signing of the Paris climate deal.
French President Francois Hollande and Canada's Justin Trudeau will join US Secretary of State John Kerry for the ceremony attended by more than 165 governments, the largest ever one-day signing of an international agreement.
Held on Earth Day, the ceremony comes four months after the hard-won deal was clinched in Paris and marks the first step toward binding countries to the promises they made to cut greenhouse gas emissions.
Oscar winner and environmental activist Leonardo DiCaprio will be on hand to praise leaders for signing, urge others to do the same and appeal to all to turn their commitments into action.
While the US, China and India — the world's top greenhouse gas emitters — will not be represented at their highest level, there will be some 60 heads of state and government on hand for the signing.
With inputs from AFP