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The Expanding Universe
Transcript of The Expanding Universe
Vesto Slipher measured the Doppler Shift of spectral lines from spiral galaxies and discovered that most galaxies exhibited redshifts in their spectral lines, which he interpreted to mean that the galaxies were moving away relative to us so their spectrum was shifted to longer wavelengths.
Extending the work of Slipher, Hubble took long exposures of faint galaxies. He then measured the shift of specific spectral lines relative to those produced by reference arc lamps in the spectrograph and calculated values for the galaxy velocities.
The Prelude Continued
Applying the period-luminosity relationship, Hubble calculated the distance to these Cepheid stars, and hence the distance to the Andromeda Galaxy.
"The Illustris Simulation." Illustris. Web. <http://www.illustris-project.org/>.
"Australia Telescope National Facility." Edwin Hubble & the Expanding Universe. Web. <http://www.atnf.csiro.au/outreach/education/senior/cosmicengine/hubble.html>.
Using his data, Hubble determined that there was a distance-velocity relationship for galaxies, a fact later to be known as Hubble's Law and is interpreted as evidence for the expanding universe.
Hubble found several nearby galaxies had blue shifted lines meaning that they were moving towards the Milky Way, while most galaxies exhibited red-shifted spectral lines meaning that they are moving away.
BY Mary Gutierrez, and Caleb Coleman
During the early 20th century, astronomers were attempting to discover what the "gaseous, fuzzy clouds of in the distance" were.
Edwin Hubble used the Hooker Telescope to study the Andromeda Galaxy, in which he identified several Cepheid variable stars. He determined the period of these Cepheid variable stars by observing their varying luminosity over time.
m = Apparent Magnitude
M = Absolute Magnitude
d = Distance (In Parsecs)