Why does Sky get Dark at Night

200 years ago there have been theories that cause dark sky at night is because the hydrogen gas cloud covered the light from the stars and thereby preventing transmission of light to the Earth at night.

Currently, these hypotheses seem right.

If the universe is infinite or contain a huge number of stars, why the sky is not as bright as day when the sun goes down? Certainly the stars has been coated with something obscure the light at night.Most scientists have concluded that the current number of stars is about a trillion, so little to make the night sky bright if the universe continues to expand. But a 15-year project by researchers at the University of Nottingham has reassessed the photographs from the Hubble Space Telescope and NASA found that the number of stars observed in the universe actually much larger.

In fact, there are at least 2,000 billion galaxies in the night sky, more than 10 times higher than the previous estimates, this means that a sufficient number of stars in order to make the sky bright even in night.

200 years ago there have been theories that cause dark sky at night is because the hydrogen gas cloud covered the light from the stars and thereby preventing transmission of light to the Earth at night. Currently, these hypotheses seem right.

Scientists have concluded that because of the distant galaxy light from the star is absorbed capital of dust and gas between the galaxies, more precisely, to prevent hydrogen gas layer between the Earth and the galaxy. They also believe that the expansion of the universe stretches light waves that follow will increase the wavelength of them led to a change at the end of the red of the spectrum. And the truth is that the red light is not easy to see.

Christopher Conselice, professor of astrophysics at Nottingham, who led the research, said:

“The number of galaxies in the universe are the basic numbers we want to know and it always boggles the mind me that more than 90 % of galaxies in the universe has not been studied to come. “

Professor Conselice said other astronomers have demonstrated the existence of clouds of hydrogen by studying the spectrum of light. However, when they do not know whether the galaxies in the back wall of the hydrogen. In addition, a number of distant galaxies in the universe, so their light can not reach the Earth.

“Who knows whether these interesting properties and attractive that we will find when we study the galaxies with the generation of modern telescopes in the future next. These galaxies could be clues to more discoveries of astrophysics prominent in the future, “ Conselice said.

Scientists have spent decades trying to find answers to the question how many galaxies exist in the universe. The observations from the early years of the 90s led astronomers to the belief that the figure was around 100 billion, but recent studies have shown that this estimate is too low.

Professor Conselice and his team have tried to transfer the images from the Hubble Space Telescope into 3-D in order to perform more accurate measurements.

In addition, they used a new mathematical model allows to infer the existence of galaxies that generations current telescopes can not see. This leads to the conclusion quite surprised that so that the number of existing galaxies we see and our volumes significantly, to 90% of the observed galaxies in the universe must be seen by current telescopes.