An astronaut aboard the ISS took an unusual image of the Earth from space, showing two blue flashes of light twinkling in our planet’s atmosphere. This dazzling pair looks like something inexplicable and mysterious, but in fact these lights are the result of two unrelated natural phenomena that simply happened at the same time.
The image was taken last year by an unnamed Expedition 66 crew member as the ISS passed over the South China Sea. However, the photo was published quite recently.
NASA scientists explained that the first flash of light seen at the bottom of the image is a massive lightning strike somewhere in the Gulf of Thailand. Such discharges are generally difficult to see from the ISS, as they are usually obscured by clouds. But this particular strike occurred near a large tear at the top of the clouds, causing the lightning to illuminate the surrounding walls of the cloud structure, creating a striking glowing ring.
The second flash, which can be seen in the upper right corner of the image, is the result of moonlight bending. The orientation of the natural satellite of the Earth in relation to the ISS means that the light it reflects from the Sun passes directly through the planet’s atmosphere, which turns it into a bright blue spot with a fuzzy halo. This effect is caused by some of the moon’s light being scattered by tiny particles in the atmosphere.
Also visible in the photo is a glowing web of artificial lights emanating from Thailand. Other notable sources of light pollution in the image come from Vietnam and Hainan Island, China’s southernmost region, although these light sources are largely obscured by clouds.