It seems that the first person I thought seriously about why the sky is dark at night, in a serious and scientific, was the German Dr. Heinrich Olbers, who lived in Bremen, and in 1826, decided to find a mathematical answer to that simple question.

Astronomy was the passion of his life, even in the days when he worked as a doctor, most of the nights clear and unobstructed spent watching the sky from an observatory built on his house. Such observations led him to discover a comet in 1815, which bears his name, and other celestial bodies. But the best of his works was inquiring about a question I had, apparently, a very simple answer.

Dr. Olbers imagined that the sun sends us only about half of the light that, theoretically, should reach us. The other half would come from the stars, hundreds of thousands of millions, are scattered through space. And with all that amount of light from stars, why the night is not as bright as day?

The number of stars fills the ability to understand the human mind, and space is so huge that for the most part empty.

Dr. Olbers only knew a small part of the grand universe, and the number of stars he knew was very high. Taking into account that amount, the brilliance of those bodies and distance, and performing calculations, made it to an astonishing conclusion, with all the light emitted by billions of stars, space should not be dark at night, and our Earth would be full of light and heat, even at night, and worst of all is that we would be grilling.

But why does not happen? Why is the sky dark at night, despite that?

Dr. Olbers concluded that a fog star would have to be absorbing as much light from stars, but other scientists were not convinced by this argument finding it insufficient. Finally, after much debate, this issue became the “paradox of Olbers.”

And so went one hundred years, but at 16 years of Dr. Olbers have raised this issue, the key was found, but at that moment no one could see the relationship between them.

In 1842, a math teacher named Austrian Christian Doppler discovered a phenomenon that now bears his name: the Doppler effect. This effect is seen when a person is placed on one side of the railway line, and as a train is approaching, the whistle of the locomotive sounds more and more acute, but after the machine passes, the tone of the whistle is increasingly low.