Size and Scale of the Universe
- 1. Size and Scale of the Universe
- 2. Size and Scale of the Universe # Street City State Country Continent Hemisphere Planet Orbit Star? …? … … … …
- 3. Size and Scale of the Universe Realm Guesses Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Earth Salt grain Salt grain Salt grain Salt grain Salt grain Salt grain Sun Solar System Solar Neighborhood Galaxy Local Group (of galaxies) Local Supercluster (of galaxies) Universe
- 4. Size and Scale of the Universe Realm Actual Size (diameter in km) Actual Size (in light-years) Multiple “X” larger than Earth Scale Model Earth 12,700 (1.27E+4) 1.4 billionths (1.4E-9) 1 salt grain (0.1 mm) Sun 1.39 million (1.39E+6) 1.5 ten-millionths (1.5E-7) 109 (1.09E+2) gum ball (1.09 cm) Solar System 30 billion (3.0E+10) 0.0032 (3.2E-3) 2.34 million (2.34E+6) football stadium (234 meters) Solar Neighborhood 378 trillion (3.78E+14) 40 (4.0E+1) 30 billion (3.0E+10) ~ size of Moon (3,480 km) Galaxy 946 quadrillion (9.46E+17) 100,000 (1.0E+5) 75 trillion (7.5E+13) 5.4 Suns (7.5 million km) Local Group (of galaxies) 62 quintillion (6.15E+19) 6.5 million (6.5E+6) 4.8 quadrillion (4.8E+15) orbit of Mars -diameter (~3 AU) Local Supercluster 1.2 sextillion (1.2E+21) 130 million (1.3E+8) 97 quadrillion (9.7E+16) orbit of Neptune -diameter (~60 AU) Universe 860.9 sextillion (8.6E+23) 91 billion (9.1E+10) 68 quintillion (6.8E+19) Oort Cloud-radius (48,000 AU or 0.76 ly)
- 5. Size and Scale of the Universe Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002
- 6. Size and Scale of the Universe • Planet where we all live • Comprised primarily of rock • Spherical in shape • 12,700 km in diameter • It would take 17 days to circumnavigate the globe driving a car at 100 km/hr (62 mph) • At the speed of light, it would take 0.13 seconds to go all the way around Earth Image Credit: NASA/JPL/GSFC
- 7. Size and Scale of the Universe • The star that Earth orbits • Composed primarily of hydrogen and helium gas • Uses nuclear fusion in its core to generate heat and light to allow itself to resist the crushing weight of its own mass • Spherical in shape • 1.39 Million km in diameter Image Credit: SOHO/NASA/ESA
- 8. Size and Scale of the Universe • The Sun’s diameter is 109 times greater than that of Earth • Over 1 million Earths would fit inside the Sun’s volume • The average distance between the Earth and the Sun is called an Astronomical Unit (AU) - it is about150 million kilometers • It would take 11,780 Earths lined up side to side to bridge the gap between Earth and Sun (or 107 Suns) Image Credit: SOHO/NASA/ESA
- 9. Size and Scale of the Universe • 8 planets, several dwarf planets, thousands of asteroids, and trillions of comets and meteoroids • Mostly distributed in a flat disk • Pluto orbits ~40 AU from Sun • The Sun blows a constant wind of charged gas into interstellar space, called the Solar Wind • The boundary between the Solar Wind and interstellar space (the Heliosphere) is around 100 AU from the Sun (200 AU diameter) Imagecredit:NASA Imagecredit:NASA/JPL-Caltech/R.Hurt Imagecredit:NASA
- 10. Size and Scale of the Universe • The region of the Galaxy within about 20 light- years of the Sun (40 light- years diameter) • A light-year is the distance that light travels in one year (~10 trillion kilometers or 63,000 AU) • The neighborhood stars generally move with the Sun in its orbit around the center of the Galaxy • The ‘Solar Neighborhood’ is a vague term not scientifically defined Note: the size of the stars in this image represents their brightness, they would actually all be specks at this distance Image credit: Andrew Colvin
- 11. Size and Scale of the Universe • The Milky Way Galaxy is a giant disk of stars 100,000 light-years across and 1,000 light-years thick • The Sun is located at the edge of a spiral arm, 30,000 light- years from the center • It takes about 250 million years for the Sun to complete one orbit • There are over 200 billion stars in the Milky Way Image credit: R. Hurt (SSC), JPL-Caltech, NASA
- 12. Size and Scale of the Universe • About 6.5 million light-years in diameter • Contains 3 large spiral galaxies -- Milky Way, Andromeda(M31), and Triangulum(M33) -- plus a few dozen dwarf galaxies with elliptical or irregular shapes • Gravitationally bound together—orbiting about a common center of mass • Roughly shaped like a football Image Credit: Andrew Colvin
- 13. Size and Scale of the Universe • The Local Supercluster is about 130 million light- years across • It’s a huge cluster of thousands upon thousands of galaxies • Largest cluster is the Virgo cluster containing well over a thousand galaxies • Clusters and groups of galaxies are gravitationally bound together, however the clusters and groups spread away from each other as the Universe expands • Roughly pancake shaped Image credit: Andrew Colvin
- 14. Size and Scale of the Universe • Great walls and filaments of galaxy clusters surrounding voids containing no galaxies • Probably at least 100 billion galaxies in the Universe • Surveys of galaxies reveal a web-like or honeycomb structure to the Universe Image Credit: Dr Chris Fluke, Centre for Astrophysics and Supercomputing, Swinburne University of Technology Image Credit: G.L. Bryan, M. L. Norman, UIUC, NCSA, GC3 • Computer simulations also show a similar structure, often called the “Cosmic Web”
- 15. Size and Scale of the Universe Image Credit: Springer et al (2004) • The Observable Universe is currently about 91 billion light-years across • There could be (and likely is) much more beyond that, but we cannot see it from this point in spacetime • Note: The matter that we can see glowing shortly after the Big Bang (detected by the light it emitted 13.7 billion years ago) is now about 46 billion light-years away due to the ongoing expansion of the fabric of the Universe
- 16. Size and Scale of the Universe
- 17. Size and Scale of the Universe There are two basic methods for measuring astronomical distances: the standard rulers and the standard candles... • Use knowledge of physical and/or geometric properties of an object to relate an angular size with a physical size to determine distance • Examples: Parallax, Moving Clusters, Time Delays, Water MASERs • Considered to be a direct or absolute measurement R d θ d = R/Tan(θ) ≅ R/θ
- 18. Size and Scale of the Universe • Requires very precise measurements of stellar positions, and long baselines • Need telescopes with high resolution, and must observe over several years • The Hipparchos satellite measured distances using this method for tens of thousands of stars within 1,500 light-years of the Sun ImageCredit:B.Mendez
- 19. Size and Scale of the Universe Use knowledge of physical and/or empirical properties of an object to determine its Luminosity, which yields distance via the Inverse Square Law of Light • Examples: Cepheid Variables, Supernovae, TRGB, Tully-Fisher • Considered to be relative until tied to an absolute calibration Image credit: Splung.com
- 20. Size and Scale of the Universe • Cepheid Variables are a type of giant star whose surface pulsates in and out with a regular period. That Period of pulsation is related to the Luminosity of the star • The Large Magellanic Cloud contains hundreds of Cepheids all at the same distance. Which allows for robust determination of the Period Luminosity Relationship Image credit: NASA Image credit: NASA
- 21. Size and Scale of the Universe Image credit: David Hardy, PPARC Image credit: European Southern Observatory • Supernovae are EXTREMELY BRIGHT explosions that can be seen from enormous distances • Their absolute luminosity is known and fades at a consistent rate, so we can determine their distance • White dwarfs capturing matter from a nearby star explode in special kind of Supernova called Type 1a • Type 1a supernovae are found by their spectral signature
- 22. Size and Scale of the Universe To measure cosmological distances a ladder of methods is used to reach further out into the Universe. Each “rung” in the ladder depends on the calibration of the methods “below” it. Image credit: Addison Wesley