On September 1st, Chen Dong and Liu Yang, astronauts of my country's Shenzhou 14th, successfully walked out of the cabin door. This is the first time that Chinese astronaut has exited the main channel from space station - Wentian experimental cabin airlock cabin into space.
However, attentive friends will find that the background of the starry sky behind the astronauts is actually dark in the pictures of the astronauts leaving the capsule. Where have the stars in the vast starry sky gone?
The light of the stars was "filtered" by the camera
Yang Yuguang, vice chairman of the International Astronautical Union Space Transportation Committee, told the Science and Technology Daily reporter that it was not the "weird disappearance" of these stars that caused this phenomenon, but the "selection" of the camera's exposure parameters. That is to say, the photographer uses technical means to make the stars in the photo or video "invisible" in the deep space.
"In the universe, stars are the dimmer subjects. Conversely, the space station and astronauts in the sun will be very bright. The camera cannot 'see' bright objects and 'see' special objects at the same time How to choose a dark object? Obviously, during the outboard activities, it is the first task to clearly capture the details of the astronauts, space station modules and the earth, that is, set the corresponding camera exposure parameters based on bright objects. "Yang Yuguang said .
Specifically, when the camera locks on the space station and astronauts who are out of the cabin, because the space station and the astronauts are very bright, the camera must control the amount of light entering and reduce the exposure time in order to capture normal exposure pictures. This low-value adjustment of exposure and aperture inevitably "filters out" the faint glow of stars in space, so the resulting picture is a dark night sky with no stars on it. If
wants to shoot relatively dim stars, the camera should increase the amount of light and increase the exposure time. However, this will cause the space station and astronauts in the picture to appear "overexposed" and become white. "The stars in the universe have always been there, it's just that we artificially 'ignored' the stars by adjusting the camera in order to capture the ideal picture of the astronauts leaving the cabin." Yang Yuguang concluded. What's the difference between
watching stars in space?
astronauts exiting the capsule "filtered" the stars, so can astronauts in space see the stars? Is it the same as the stars we see on Earth?
Ping Jinsong, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, pointed out that there is no atmospheric scattering in space, and sunlight travels in a straight line, so the entire space will not be illuminated. In dark space, astronauts can see the sky full of stars.
"When an astronaut first steps out of the hatch, if he looks at the earth and his eyes are adapted to bright things, then looking up at the dark universe, he may not be able to see the stars for a while. But the human eye is very adaptable, and the eyes After getting used to the darkness, you can see the stars." Yang Yuguang said.
On October 15, 2003, astronaut Yang Liwei took the Shenzhou 5 manned spacecraft , which opened the first space gaze of Chinese astronauts. According to his recollection, the moon and stars seen in space were clearer and brighter, and the stars did not "blink".
On September 27, 2008, astronaut Zhai Zhigang exited from the Shenzhou 7 manned spacecraft, the first time Chinese people "walked in space". The space in front of him "can't see the end at a glance", and he sees "much more stars than on Earth".
On December 9, 2021, at the " Tiangong Class " of the Chinese space station , astronaut Wang Yaping revealed that astronauts can see the sunrise 16 times a day, because the space station circles the earth every 90 minutes.
"The stars that astronauts see in space are indeed different from what we see on Earth." Yang Yuguang said that there are factors such as atmosphere and artificial light sources on the earth that block or interfere, making the starlight weaker, and " Twinkle, twinkle," and fewer stars are visible to the naked eye. In space, because there is no atmospheric barrier or occlusion, the stars viewed by astronauts have three characteristics: less flickering, clearer and brighter, and more stars.
Ping Jinsong also said that space is a vacuum, there is no atmospheric turbulence , so the stars will not "blink", there are only stars, no stars twinkling. Therefore, there will be no halos or halos around stars, planets or the moon, and the stars will be more translucent.
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