In 1923an incredible find by the astronomer Edwin Hubble has completely transformed our understanding of the cosmos. By peering into a star in the Andromeda Galaxy, Hubble not only expanded our understanding of the dimensions of the universe, but also laid the foundations for modern cosmology. Thanks to this, we realized that the universe is much bigger than we thought.
What did Hubble find in Andromeda?
With the Hooker telescope of 254 cm at the Mount Wilson Observatory in California, Edwin Hubble spotted a special star in the Andromeda galaxy, located 2.2 million light years. This star, named V1is incredibly faint in brightness, shining only 1/100,000th that of the faintest stars visible to the naked eye. V1 is one of a rare type of pulsating star called Cepheid variables. They are super important for astronomers because they serve as milestones for measuring distances in space thanks to a feature discovered by Henrietta Swan Leavitt : the pulsation period of Cepheids is directly linked to their intrinsic luminosity.
What an upheaval for science!
Hubble's discovery of V1 had enormous repercussions on astronomy. It showed that our Milky Way is only one among hundreds of billions of observable galaxies. It opened a new era in cosmology and this advance was hailed by prestigious institutions like Carnegie Science and the NASA at the 245th meeting of the American Astronomical Society in Washington, DC
Not everyone was happy. The astronomer Harlow Shapleyconvinced that the Milky Way constituted the entire universe, was truly disconcerted by this discovery. He confided his disillusionment to fellow astronomer Cecilia Payne-Gaposchkin, saying: “This is the letter that destroyed my universe. »
And after? Hubble's legacy
Edwin Hubble's legacy continues today with the Hubble Space Telescope that bears his name. This telescope allows us to explore areas ten times more distant than what Hubble could observe in its time. Thanks to him, we discovered a universe filled with active stars, colliding galaxies and even wandering black holes.
But Hubble didn't stop there; he also noticed that the farther away a galaxy is, the faster it seems to move away from us. This essential observation led to the theory of an expanding universe. Even before that, Vesto Slipher had collected the first data on the red shift of galaxies, and it was thanks to the combined analyzes of Hubble and Slipher that Georges Lemaître concludes with an expanding universe.
-Key concepts you need to know
The famous law known as the Hubble–Lemaître law explains this proportionality between the distances of galaxies and their redshifts. The rate at which this universe is expanding is defined by what is now called the Hubble constant. In 1998another great leap was made with the discovery of the mysterious phenomenon called “dark energy”, showing that the expansion of the universe is accelerating.
Today, thanks to the Hubble Space Telescope, we can estimate the approximate age of the universe at approximately 13.8 billion years. Future projects like the Roman Space Telescope promise even more insight into the mysteries surrounding dark matter and dark energy.
As we continue our exploration of the vast cosmos that surrounds us (and that fascinates us), it becomes evident that each new discovery reinforces our wonder at this complex and mysterious universe. Edwin Hubble's legacy still lives in every star observed and every galaxy explored thanks to modern technologies that continually push the boundaries of human knowledge.
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