An astronaut takes a picture showing mysterious blue dots in Earth's atmosphere
An astronaut aboard the International Space Station captured an image of Earth that contains two bright blue dots shining in the planet's atmosphere.
According to the “Live Science” website, the photo was taken last year by a member of the Expedition 66 crew, whose name was not disclosed, during the passage of the International Space Station over the South China Sea. The image was posted online on Oct. 9 by NASA's Earth Observatory.
According to NASA, the dazzling blue dots floating above the ground seemed strange, but they are actually the result of two unrelated natural phenomena that just happened at the same time.
The first point of light, which can be seen in the lower part of the image, is 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 by clouds.
The second blue dot, which can be seen at 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 blob with a mysterious halo.
But this particular strike occurred next to a large circular gap at the top of the clouds, causing the lightning to illuminate the surrounding walls of the cloud's caldera-like structure, creating an amazing luminous ring. Different colors of visible light have different wavelengths, which affects their interactions with atmospheric molecules. Blue light has the shortest wavelength and is therefore the most scattered, causing the moon to turn blue in this image.
This effect is caused by the scattering of some of the moonlight from small particles in the Earth's atmosphere, according to the Earth Observatory.
This effect also explains why the sky appears blue during the day, because the blue wavelengths of sunlight scatter more and become more visible to the human eye, according to NASA.
The image also shows a glowing web of artificial lights coming from Thailand. Other notable sources of light pollution in the image emanate from Vietnam and Hainan Island, in the far south of China, although these light sources are largely obscured by clouds.
The orange halo parallel to the Earth's curvature is the edge of the atmosphere, which is known as "Earth's Edge" when viewed from space, according to the Earth Observatory.
Source: websites