On this day, 130 years ago, Edwin Hubble was born in Marshfield, Missouri. Hubble is thought to be one of the greatest astronomers of all time. From NASA.gov:
Most astronomers of Hubble’s day thought that all of the universe — the planets, the stars seen with the naked eye and with powerful telescopes, and fuzzy objects called nebulae — was contained within the Milky Way galaxy. Our galaxy, it was thought, was synonymous with the universe.
In 1923 Hubble trained the Hooker telescope on a hazy patch of sky called the Andromeda Nebula. He found that it contained stars just like the ones in our galaxy, only dimmer. One star he saw was a Cepheid variable, a type of star with a known, varying brightness that can be used to measure distances. From this Hubble deduced that the Andromeda Nebula was not a nearby star cluster but rather an entire other galaxy, now called the Andromeda galaxy.
In the following years, he made similar discoveries with other nebulae. By the end of the 1920s, most astronomers were convinced that our Milky Way galaxy was but one of millions in the universe. This was a shift in thought as profound as understanding the world was round and that it revolved around the sun.
Hubble then went one step further. By the end of that decade, he had discovered enough galaxies to compare to each other. He created a system for classifying galaxies into ellipticals, spirals and barred spirals — a system called the Hubble tuning fork diagram, used today in an evolved form.
But the most astonishing discovery Hubble made resulted from his study of the spectra of 46 galaxies, and in particular of the Doppler velocities of those galaxies relative to our own Milky Way galaxy. What Hubble found was that the farther apart galaxies are from each other, the faster they move away from each other. Based on this observation, Hubble concluded that the universe expands uniformly. Several scientists had also posed this theory based on Einstein’s General Relativity, but Hubble’s data, published in 1929, helped convince the scientific community.
In honor of this great physicist, you are going to do some physics! YAAYY!!! Try these