Amazon rainforests which are often referred to as the 'lungs of the planet' have been burning for more than 20 days. The smoke from the fire has been so intense that it's visible from space, as captured by NASA and NOAA satellites.  

The smoke from these forests has been far reaching, most recently covering Brazil's biggest city Sao Paulo in a cloud of darkness. Notably, the origins of fire is 2700 km away, and it has still managed to affect far away places.

Source: Express

Several media outlets have also been presuming the cause of such an unusual event, one of which is the arrival of a cold mass of air, which increased the number of low clouds and fog over the city.  

Source: Express

The second is as the cold front expanded, a change in the wind patterns brought into the city smoke from forest fires in the Amazon region and other parts of South America, thousands of miles away.  

According to reports, the fires have been raising concerns that the rainforest, which is one of the most biologically diverse regions on Earth, might be at the risk of agricultural use which requires land-clearing operations.

An environmental scientist has also mentioned

People stored black water from the rainfall after the massive smoke cloud reached Sao Paulo. 

People have been sharing pictures of the darkness that has covered Sao Paolo in the middle of the day.

One of the most protected parts our planet is burning at an unimaginable speed as the world watches.