It's December 30th. On this day in 1924, 🗽 American astronomer Edwin Hubble (20 Nov 1889 – 28 Sep 1953) announced the object in the sky then known as the "Andromeda Nebula" was a 🌌 galaxy. This revelation instantly doubled the number of galaxies and stars in the known universe and hinted at a vastly greater number, for until then every star that could be seen in the sky, either by the naked eye or by telescope, had been assumed to belong to our own Milky Way Galaxy. An entirely new scientific field was born – cosmology.
Hubble based his announcement upon his ingenious analysis of a Cepheid variable ⭐ star in the Andromeda Nebula. In 1912, 🗽 American astronomer Henrietta Leavitt had invented a formula for calculating the distance from our Solar System to Cepheids. Using Leavitt's formula, Hubble determined that a Cepheid inside the Andromeda Nebula was much further away than anyone had thought and that, therefore, the nebula was not a gaseous cloud inside our own galaxy, but was in fact a galaxy of stars just like the Milky Way… and very far away.
Later, in 1929, Hubble provided observational proof of 🇫🇷 French astronomer Georges Lemaître's "Expanding Universe" hypothesis. The resultant Hubble-Lemaître Law states that galaxies are receding from Earth at speeds directly proportional to their distances, like spots on an inflating 🎈 balloon. Hubble calculated the rate of this expansion, which is now known as the Hubble constant, to be 170 kilometers per second per light year of distance. These discoveries led Hubble, Lemaître, and most other astronomers of that era to the obvious conclusion that an expanding universe, much like the result of an 💥 explosion, must have once existed in a tight unexploded state. Lemaître coined this hypothesis the "Primeval Atom Hypothesis," which of course is now known all over the planet, thanks to 📺 Dr. Sheldon Cooper and friends, as the "Big Bang Theory."
NASA paid tribute to Hubble's great and many contributions to astronomy and cosmology by naming its first "Great Observatories" 🔭 space telescope after him. This workhorse eye in the sky was launched into low-Earth orbit in 1990. It is one of the largest and most versatile research tools ever devised by Homo sapiens and has been responsible for countless scientific, engineering, and technological breakthroughs. Five days ago, on 25 Dec 2021, NASA launched Hubble's de facto successor, the James Webb Space Telescope into outer space. ☮️ R.I.P., Edwin… Jamiese of Pixoplanet
