Astronomer Edwin Powell Hubble

Azkune Mendia, Iñaki

Elhuyar Fundazioa

Hubble has been without XX lips. One of the brightest stars in the sky of 20th century astronomers (among other things because it discovered galaxies and the expansion of the universe) universe) and since the centenary of his birth is now celebrated, we consider that this line of scientists deserves to be longer than on other occasions.

Edwin P. The astronomer HubblE entered the North American village of Missouri, Marshfield, on November 20, 1889. Being the fifth of seven brothers, as a young man he studied at the University of Chicago, where the prestigious astronomer George Ellery Hale was his teacher.

But Hubble had to choose between being a lawyer as his father or making a living as a professional boxer (that was also very good). He preferred his father's path and after obtaining a scholarship, in Oxford (Great Britain), he studied law with Rhodes as a professor. As a student of Oxford he played a conbate with the French boxer champion Georges Carpentier (the two of the heavy weights).

After completing his law career he returned to North America, where he worked in the Kentucky court. He soon got bored and immediately directed his steps to astronomy. From 1914 to 1917 he worked at the Yerkes Observatory in Wisconsin.

At the end of World War I, in 1919 he began working at the California mountain observatory Wilson, with a hundred inch telescope at his disposal.

At that time Hubble was concerned about the luminous spots of the nebulae. Some of them were investigated by Messier a century and a half earlier, but there were still many questions about them unanswered. Then the dimensions of our galaxy (our Sun was already the Milky Way) were perfectly calculated by Harlow Shapley, but outside our galaxy he wondered if there was anything more than the Magellanic Clouds studied by Leavitt.

Hubble thought the way to answer this question was in the nebulae. Some nebulae were, undoubtedly, clouds of dust and gas illuminated by the stars of our galaxy, but the luminosity of others, like that of Andromeda, was an influence of something else, according to Hubble. Perhaps within this nebula there would be many modest stars and with their luminosity they would reach an effect similar to that of our Milky Way. As the clarity of Andromeda was less than that of Esnebide, Andromeda went much further.

In the Andromeda nebula, nova stars were detected, but until the time of Hubble no common stars were detected. However, in 1924, through its large telescope, the largest of the time, it detected common stars within the Andromeda nebula. Hubble also showed that some of these stars were variable headaches. Using the period and luminosity law of Shapley and Leavitt, Hubble calculated that it was 800,000 light-years from Earth, eight times the distance from Earth to the nearest star in our galaxy. (Twenty years later it was shown that the distance was actually greater). Andromeda, therefore, was an outer nebula to our galaxy.

Then many other nebulae were discovered, one year from billions, and Shapley proposed to call them galaxies, because our Milky Way was another like them.

Hubble continued to classify galaxies according to their shape and suggesting opinions about their evolution, and in 1929 dared to publish the interpretation of the radial velocities of galaxies measured by Slipher. He said that this phenomenon, thinking that the universe is constantly expanding, could be better understood. Taking into account this, the distance between galaxies was increasing and they would move away from the observer who existed at any point in any galaxy.

Then, far away from us, the speed of distance would be equal to the speed of light and we would have no proof of things after that point, because the light itself would not reach us. At a distance from us to that point he has been called the Hubble radio, and it is the radius of the sphere that occupies the part of the universe that we can know. Hubble radio has been estimated at 13 billion light-years, that is, the part of the universe we can know is a sphere of 26 billion light-years.

When Hubble said galaxies were moving away from each other in 1929, he knew that the light of distant galaxies was shifting to red by Doppler effect. In fact, when the light source was moving away from the observer, the wavelength of the light he received was greater. A similar phenomenon occurs with the sound we receive when a train leaves us. The sound of the siren has a longer wavelength (lower pitch) for the still person outside than for the passenger of the train.

But Hubble also said something more. For him the speed of moving away from galaxies was proportional to the distance that separated us. He said the ratio between the speed of distance and distance was constant (Hubble constant). According to Hubble's calculations, the value of the constant was 500 km/s divided by 1,000,000 parsec (3,260,000 light years). (Later it was shown that the value of the Hubble constant is F(75/10 6 km/s-parsec).

If Hubble was straight, knowing the velocity of moving away from galaxies, the distance to the galaxy could be calculated and knowing the distance, the size of the galaxy.

However, there was another problem to solve. And, if galaxies move away from each other, it can be thought that they would be united long ago. If Hubble's calculations were not wrong, galaxies began to move away about two billion years ago.

However, geologists did not agree with these figures, since according to their field studies, the age of the Earth was at least three billion years. The geologists were right, as Walter Baade later demonstrated.

All current cosmogonic schemes are forced to explain this removal of galaxies, and if any theory does not remove them, it must clarify why we see them away.

However, now the most accepted theory is that of the Big Bang or Big Bang, according to which all galaxies were united and concentrated. However, a big explosion broke the concentrated mass and began to expand. It continues in that, as Hubble demonstrated.

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