Viral Video of Red Sky, IPB University Professor Straightens the ‘Falling Sun’ Narrative

A short video showing the phenomenon of a red sky during the day, which was claimed to have occurred in Aceh some time ago, has been discussed by the public. The narrative of the ‘falling sun’ also circulated and triggered public confusion. 

Responding to this, Professor of Theoretical Physics at IPB University who is also the lecturer of Optics and Photonics, Prof Husin Alatas, gave a scientific explanation of the phenomenon.

“Clear sky conditions are usually blue due to the scattering of light by air molecules in the atmosphere,” said Prof Husin starting his presentation.

Furthermore, the white light of the sun consists of various wavelengths. “When light hits air molecules whose size is very small compared to their wavelength, Rayleigh scattering occurs. In this process, blue light with small wavelengths is scattered more than red,” he explained.

This causes the sky to look blue during the day. However, when the sun rises or sets, the sky tends to look red-orange. “The position of the sun below the horizon makes red and orange light, which is not scattered much, more dominant in the observer’s view,” he added.

Prof Husin also explained that in addition to Rayleigh scattering, there is also Noodle scattering which occurs when light-blocking particles are larger, such as aerosols or water droplets. 

“Mie scattering causes light to be scattered evenly for all wavelengths. This is why the clouds look white, even though the sky is blue,” he said.

In the case of the viral video, if it was taken during the day, it is likely that the atmosphere contains a high concentration of aerosols or fine dust, for example due to pollution, fire smoke, or volcanic dust.

“These particles can absorb blue and violet light and reflect more red and orange light. The combination of selective absorption and Mie scattering makes the sky appear red even though the sun is still high,” explained Prof Husin.

Regarding the ‘falling sun’ narrative that is spreading in the community, Prof Husin emphasized that the claim is not scientifically correct. “The sun is a star with a volume of 1,3 million times the earth and a radius of 110 times the radius of the earth. The distance is about 150 million kilometers from the earth. So, it is impossible for the sun to fall to the earth,” he said. (dr) (IAAS/NRA)