Tanabata Day: Can astronauts see the Milky Way on the moon? How is it different from the earth?

On a sunny summer day, when you look up at the sky, there will be a Milky Way in the sky, just like the same shining Tianhe, which was vividly called the Milky Way by the ancients. Today, we all know that the so-called Milky Way is only a part of the Milky Way seen on the earth.

The earth and the entire solar system we live in are like a tiny speck in the Milky Way, because the Milky Way is so vast, with a diameter of 16, light years, and the number of stars like the sun reaches about 3 billion.

It is such a large number of stars that together, like pearls, form a brilliant Milky Way. Originally, watching the Milky Way on earth was a rare beauty in the summer night sky, but today, this beauty has disappeared from most people's memories.

Maybe you can see it occasionally in a remote mountain village with a clear night sky, but for those children who live in the city, you may never see the magnificent sight with your own eyes.

Just because the light pollution in the city is too serious, there are only a few sparse stars with high brightness in the bright night sky, so that countless stars in the previous generation can now be counted clearly.

We know that there are no stars on the earth, or the number of stars we see is few. On the one hand, there is light pollution, on the other hand, there are impurities in the air, which will block some light or cause light scattering.

For these reasons, when you look up at the starry sky in some underdeveloped areas or places far away from human habitation, you will see the magnificent Milky Way that many people saw when they were young.

With the development of China society and the reflection of street lamps and advertising lights, the starry sky that existed in childhood memories can only be presented in dreams. This may be a little regret after social development!

Many people have a question in their hearts. Since light pollution and the existence of the atmosphere pose a certain threat to the brightness of planets on the earth, the stars they see will be much brighter in space!

But judging from the photos sent back by astronauts from the moon, outer space is like a dark curtain, and many people think that there are no stars on the moon based on these photos.

is this really the case?

Let's take Apollo 13 as an example. After landing on the moon, two astronauts, Armstrong and Aldrin, took a lot of photos, many of which were set in space.

But in these photos, few stars are seen. Even if they are seen, there are only a few stars with high brightness, and their number is single digits, not to mention the Milky Way composed of hundreds of billions of stars.

So what makes the moon without light pollution and atmospheric scattering invisible?

Some people say that it has something to do with the moon itself. Because of the tidal force between the earth and the moon, one side of it always faces the earth, while the other side is hidden in the darkness.

when Apollo 13 first landed on the moon, it landed on the front of the moon, which is the side facing the earth. It will always face the earth and the sun, so it will be daytime on the moon, so the stars and the Milky Way can't be seen.

is this really the case?

Not really. This is to look at the moon and space from the perspective of the earth.

The reason is still related to the moon itself. As we know, the environment of the moon is special, which is almost a vacuum environment, that is, there is no air on the surface of the moon.

On the earth, the concept of the sky exists because the atmosphere scatters light and makes the atmosphere appear white, so when you look at the sky during the day, it is either blue or white.

However, because there is no atmosphere on the moon, the rays of the sun will not be scattered, but will directly act on the surface of the moon. Similarly, the rays of stars will also directly act on the moon without being scattered by the atmosphere, which is strictly brighter than that on the earth.

That is to say, in the moon and space, the light of the stars is competing with the sunlight. Because there is no atmospheric scattering, even in the daytime, the light intensity of the sun can't hide the brilliance of the stars.

But in this case, why can't astronauts see many stars on the moon, nor can they see many stars in the photos taken?

Because this is deliberately hidden from the astronauts, as for the reason, it is because the sun shines directly on the surface of the moon, and the moon is desolate, and the scenery is monotonous, and there are no green trees to ease the astronauts' visual nerves. This is like a piece of white snow. In this environment for a long time, you will get snow blindness.

In order to prevent astronauts from getting snow blindness, the lenses in the helmet are like sunglasses, which can be found from the photos taken back by astronauts. Therefore, even if the starry sky is extremely bright, astronauts can't see it, let alone the bright Milky Way.

And the camera can't shoot the stars, which is also specially adjusted. Friends who have played photography know that the camera's tolerance is different due to different scenes, and the corresponding sensitivity is also different.

On the moon, the most important thing is to take pictures of people nearby and the lunar surface, not distant stars, so the pictures taken are clear people, but the space background is dark.

During the Apollo 16 mission, the camera was adjusted to take pictures of the distant earth and space background. At this time, you can clearly see the stars in the sky, which are distributed around the earth.

Conclusion: There's a rude saying, that is, I'm willing to cut my clothes and brave the whole army. If I really put my heart on the horizontal and take off my helmet on the moon, then I will see the scene of thousands of stars competing with the sun, and the Milky Way will also appear in front of you in a brighter image. However, this beautiful scene is like fireworks. Although it is beautiful, it is short-lived. Because it is exposed to a vacuum environment, it will soon be ..........!

Actually, you don't have to go to so much trouble. Through the porthole of the space station, you can also see the stars all over the sky and the bright Milky Way. I envy those astronauts who can enjoy the beautiful scenery of the Milky Way in the space station on Tanabata!

I also wish our astronauts a happy Chinese Valentine's Day in the Tianhe core cabin!

They must be happy, because they are closer to the Cowherd and the Weaver Girl than we are on earth, and we can see their meeting more clearly.