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Scales in Space and Time in the Cosmos

Scales in Space and Time in the Cosmos. By Dr. Harold Williams of Montgomery College Planetarium http://montgomerycollege.edu/Departments/planet/. The Scale of the Cosmos. Astronomy deals with objects on a vast range of size scales and time scales.

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Scales in Space and Time in the Cosmos

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  1. Scales in Space and Timein the Cosmos By Dr. Harold Williams of Montgomery College Planetarium http://montgomerycollege.edu/Departments/planet/

  2. The Scale of the Cosmos • Astronomy deals with objects on a vast range of size scales and time scales. • Most of these size and time scales are way beyond our every-day experience. • Humans, the Earth, and even the solar system are tiny and insignificant on cosmic scales.

  3. A Campus Scene 16 x 16 m

  4. A City View 1 mile x 1 mile

  5. The Landscape of Pennsylvania 100 miles x 100 miles

  6. Earth Diameter of the Earth: 12,756 km

  7. Earth and Moon Distance Earth – Moon: 384,000 km

  8. Earth orbiting around the Sun Distance Sun – Earth = 150,000,000 km

  9. The Solar System Approx. 100 AU

  10. (Almost) Empty Space Around our Solar System Approx. 10,000 AU

  11. The Solar Neighborhood Approx. 17 light years

  12. The Solar Neighborhood New distance scale: 1 light year (ly) = Distance traveled by light in 1 year = 63,000 AU = 1013 km = 10,000,000,000,000 km (= 1 + 13 zeros) = 10 trillion km Nearest star to the Sun: Proxima Centauri, at a distance of 4.2 light years Approx. 17 light years

  13. The Extended Solar Neighborhood Approx. 1,700 light years

  14. The Milky Way Galaxy Diameter of the Milky Way: ~ 75,000 ly

  15. The Local Group of Galaxies Distance to the nearest large galaxies: several million light years

  16. 0 Large-Scale Structure Distribution of bright galaxies in the Virgo region indicates the Virgo cluster and presence of more distant, larger scale structure

  17. The Universe on Very Large Scales Clusters of galaxies are grouped into superclusters. Superclusters form filaments and walls around voids.

  18. 0 Large-Scale Structure A large survey of distant galaxies shows the largest structures in the universe: Filaments and walls of galaxy superclusters, and voids, basically empty space.

  19. 0 Cosmology with the Cosmic Microwave Background If the universe was perfectly homogeneous on all scales at the time of reionization (z = 1000), then the CMB should be perfectly isotropic over the sky. Instead, it shows small-scale fluctuations:

  20. 0 Measuring the “Deceleration” of the Universe … By observing type Ia supernovae, astronomers can measure the Hubble relation at large distances Distance  recession speed Size scale of the universe  rate of expansion It was expected that this would measure the deceleration of the universe, but …

  21. 0 The Accelerating Universe Flat decelerating universe Apparent Magnitude of Type Ia Supernovae Flat accelerating universe Red Shift z In fact, SN Ia measurements showed that the universe is accelerating!

  22. 0 The Evolution and Ultimate Fate of the Universe Today, acceleration due to dark energy dominates. Until ~ 6 billion years ago, gravity of matter was stronger than acceleration

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