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Activity Discussion Science & Technology Night sky end completely black because universe is expanding?


  • Shivani

    July 2, 2021 at 10:14 am
    Not Helpful

    No, the night sky will not remain completely black. It is true that the atmosphere is expanding, which causes many stars to be farther away from the earth, thus reducing them. But the expansion of the universe affects only the distance between galaxies. It does not affect the distance between the stars within the galaxy, or the distance between galaxies in a group. At the scale of the galaxy group at all, the gravitational force of the earth prevails over earth’s expansion. The stars in our Milky Way galaxy and nearby galaxies do not speak of their distance from the earth, even though the universe is expanding. As a result, the stars in our galaxy and other galaxies do not expand over time. Interestingly, almost all the stars that you can see in the night sky with your physical eye are located in our galaxy. This means that the expansion of the universe will not affect the appearance of the night sky, no matter how long we wait. The night sky will not be completely dark because of the expansion of the universe.

    However, powerful telescopes can detect other galaxies outside our group. If we wait long enough, the expansion of the universe will result in fewer galaxies of powerful telescopes. As the galaxy’s distance from the earth increases dramatically, its light spreads over a vast area before it reaches us, so it fades. As time goes on, more and more galaxies will be too far away to be detected by powerful telescopes. Increasing the sensitivity of our telescopes can help, but it can only do so much. The light from the receding galaxies not only dimmed, but also changed. This means that all the different colors in the Doppler light have been changed to lower frequencies due to the movement of the galaxy’s reversal. As time goes on, the speed at which a galaxy outside our galaxy slows down due to the expansion of the universe, so its light is constantly changing. The green or red light ends up being radio waves. Eventually, the redshift becomes so bad that the light is successfully diverted. There is no technological advancement that will enable telescopes to detect light that is not there. As a result, in the distant future, the universe will be so large that light from all stars and galaxies outside our galaxy will never reach the earth. Astronomers in the distant future will have to be content to study only our local galaxy group. But, again, the night sky will still look the same to the naked eye.

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