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Edwin Hubble - krótka biografia
Temat: Historia i kultura
Do some Exercises: Słuchaj i zapisuj Tworzenie zdań Ukryte słowa
Edwin Powell Hubble (November 20, 1889 - September 28, 1953) was an American astronomer. Hubble's findings changed the scientific view of the universe.
In 1925 he showed that there are galaxies beyond our own, the Milky Way. Also, he developed a method for classifying galaxies.
Then he proved the galaxies were moving away from each other. Hubble found the degree of Doppler effect (redshift) from a galaxy increased in proportion to its distance from Earth. Doppler effect is the change in pitch or colour when an object or sound comes in (higher pitch, brighter color) or moves away (lower and darker). Redshift is observed in the light spectrum
In 1929 Hubble formulated the Redshift Distance Law of galaxies, nowadays called simply Hubble's law. The law states that the greater the distance between any two galaxies, the greater their relative speed of separation. Today, the 'apparent velocities' of galaxies are understood as an increase in proper distance which occurs due to the expansion of space. Light traveling through stretching space experiences a Hubble-type redshift.
Four major achievements
According to Sandage, Hubble achieved four main things:
- A classification system for nebulae, both galactic (diffuse) and extragalactic (both nebulae inside our Milky Way galaxy, and other galaxies outside it).
- Hubble settled decisively the question of the nature of the galaxies (as being other things like the Milky Way).
- The distribution of galaxies was found to be homogeneous in distance (the galaxies were all over the universe, not in any particular location).
- The linear velocity-distance relation was established. This discovery lead to the notion of the expanding universe which is the centre-piece of the cosmology of the present day.
