Why can you see the starry sky on the ground but not in space?

Some astronauts say that you can't see the starry sky in space? On the contrary, in the eyes of astronauts, because there are no atmospheric obstacles and interference, the stars they see are much brighter than the earth, but the stars they see in space do not twinkle. Similarly, because the atmosphere does not scatter light, the sky you see is not blue, but dark black. Many people think that there are no stars in space or on the moon, which may come from some pictures on the internet, such as photos of the earth taken after Apollo landed on the moon, or photos taken on some space stations.

In those photos or pictures, there are no stars in the background of dark space, but the reason is actually very simple. People who know a little about photography will basically understand that this is mainly because the exposure time of the subject and the strength of the light source are weak. No stars can be seen in similar photos, because the main object is the earth, and the light source is reflected by the sun shining on the earth. The sun in space is very "direct" because there is no interference from the atmosphere and clouds. Moreover, the reflection, as well as the light reflected by the atmosphere of the earth's clouds, is very strong, making the earth look "bright" relative to the stars in the background (much more than the full moon, and astronauts can't look straight without protection. If you fly, you should better understand the clouds reflected by the sun through the plane. A short exposure can take beautiful photos of the earth, but the exposure time is too short to keep the starlight in the camera, so it is normal that you can't see the stars.

However, if we want to photograph the earth and the stars in a photo at the same time, the result is that the earth in the photo will be overexposed and the stars can be seen, but the earth will become a shiny flower. If astronauts are located on the side of the earth facing away from the sun, they can clearly see the starry sky and beautiful nebula in the photo after proper exposure time.

There is still a difference between human eyes and shooting equipment such as cameras, and only you can really feel it. Although most people can't fly into space, they can feel the beauty of the starry sky in the descriptions and images brought back by astronauts. This should be what the stars look like in their eyes.