An astronaut aboard the International Space Station (ISS) has captured a strange image of Earth from space containing two strange blue bright spots shining in our planet's atmosphere.
The dazzling blue dots, floating above the ground, looked strange, but were actually the result of two unrelated natural phenomena that had just occurred at the same time.
In fact, the photo was taken last year by an unnamed Expedition 66 crew member, while the International Space Station was passing over the South China Sea. The image was posted online October 9 by NASA's Earth Observatory.
The first point of light, which can be seen in the lower part of the image, represents a massive lightning strike somewhere in the Gulf of Thailand. It is usually difficult to see lightning strikes from the International Space Station, because it is usually covered with clouds. But this particular strike happened next to a large circular gap at the top of the clouds, causing lightning to illuminate the surrounding walls of the cloud's caldera-like structure, creating an astonishing luminous ring.
The second blue dot, which can be seen in the top right of the image, is caused by distorted light from the moon. The orientation of Earth's moon relative to the International Space Station means that the light it reflects back from the sun passes directly through the planet's atmosphere, turning it into a bright blue dot with a mysterious halo. This effect is caused by the scattering of some moonlight from tiny particles in Earth's atmosphere, according to the Earth Observatory.
Different colors of visible light have different wavelengths, which affects their interaction with atmospheric particles. Blue light has the shortest wavelength, and therefore the most scattered, causing the moon to turn blue in this image. This effect also explains why the sky appears blue during the day, because the blue wavelengths of sunlight are scattered more and become more visible to the human eye, according to NASA.
The photo also shows a glowing network of artificial lights coming from Thailand. Other notable sources of light pollution in the image come from Vietnam and China's southernmost island, Hainan, although these light sources are largely obscured by clouds.
The orange aura parallel to Earth's curvature is the edge of the atmosphere, which is known as the "Earth's tip" when viewed from space, according to the Earth Observatory.