The sky over the Jambi province in Indonesia turned into a dark red over the weekend after a series of forest fires throughout the country. Social media users captured the scene.

“This afternoon is not night,” Zuni Shofi Yatun Nisa wrote. “This is earth, not planet Mars. This is not in outer space. It’s us who breathe with lungs, not with gills. We humans need clean air, not smoke.”

Associate Professor Koh Tieh Yong, of the Singapore University of Social Sciences, told the BBC that this phenomenon is known as Rayleigh scattering, and has to do with certain types of particles that are present during a period of haze.

“In the smoke haze, the most abundant particles are around 1 micrometre in size, but these particles do not change the colour of the light we see,” said Professor Koh. He also added that the fact the photos were taken around noon could have caused the sky to appear more red.

According to the Copernicus Atmosphere Monitoring Service (CAMS), an European Union-based weather service that provides data on atmospheric composition, thousands of acres of ecologically important land are being burned and causing a toxic haze.