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How different is the sky in the morning and the sky at night? Why we can not see the stars in the morning or in the day?
Answer 1:

The way we look out into deep space where the stars are changes; this is because the earth moves around or orbits the Sun once each year. It is like being in the car and driving down the street; the things you see change because the car is moving. In addition at any time of the year the stars you see from sunrise to sun up vary because the earth spins on its axis once per day.

Frank Spera

Answer 2:

Well, yes that is a curious thing, why the stars disappear. So what is the sky anyway? As you surely know, the Earth is a ball (we call it “sphere”) in a large universe. You also know that the sun is also a large ball made of very hot material (essentially fire) and so it sends light and heat to the earth. In one day and one night the Earth spins around. During the day, we look toward the sun and it is light and warm and at night, we look the other direction and it is dark. That is the only difference between the sky at night and during the day. Now the universe has many many suns but they are very far away so we just see them as small stars. Any time you look up in the sky, during the day or during the night, the stars are there but during the day, there is too much light from the sun to see the stars.

Imagine you stand on a dark street and look up to a window and behind the window, there is someone with a small flash light. You will see the flashlight. But now imagine someone puts a very large and bright light into the window and shines it onto the street. You will see the very bright light and the flashlight will be hard to see because it is much less bright in comparison.

Another example: Do you know glow stickers? Stickers you can put on your wall and then they glow when you turn the light off? Well actually, they also glow when you have the lights on. However, when you have the light on, there is so much light in the room that you cannot see the dim glow from the stickers.

Whatever is brighter will win. Have you noticed that sometimes the moon is bright enough so that you can see it during the day?<./i> That can happen when the sun is not too light to win over completely.

With the sky there is another complication which is that there are actually a lot of tiny little particles in the sky above you. They make what we call the atmosphere of the Earth. These molecules absorb some of the sunlight and then start “glowing” blue. That is why the sky is blue. This blue color makes it even harder to look “through” the atmosphere to see the stars. When it is night, the atmosphere stops “glowing” blue and you can see through to the stars.

Answer 3:

You can see the stars in the day, if you know where to look and have good enough contrast (ability to tell light from dark) vision. The problem is that the sun is just too bright and casts light on everything, which makes it difficult to pick out the fainter lights of the other stars.

Answer 4:

It doesn't matter what time it is, the sky actually stays the same. The reason why it looks different to us is that the Sun is much brighter than the stars, so we don't see them. The stars are always there, the Sun just blocks them out.​ At night, when we don't see the Sun, we can see the light from the stars.

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