AST 111 Lecture Notes - Lecture 2: Spiral Galaxy, Hubble Space Telescope, Virgo Supercluster
6 Jun 2020
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Document Summary
Showed that the orbits of planets could be explained by action of gravitation. Same force that causes objects to fall to the ground on earth. Distance of stars can be measured by detecting their parallax. Nearby star should change its position against the background as the earth moves round the sun. Stars are so distant however that the parallax movement is extremely small. First successful measurement of stellar parallax was made in 1838 by friedrich. Measurements confirmed that the stars were other suns as had long been suspected. Heliometer used for measuring of stellar parallaxes. Not only was the earth no longer at the centre of the universe. Sun was just one of billions making up the milky way galaxy. In early 20th century, astronomers began to realize this can"t spiral nebulae were star systems like the galaxy of the milky way galaxy. With telescopes, can see distances of billions of light years revealing many billions of galaxies.
