Size and Scale of the Universe SIZE AND SCALE OF THE UNIVERSE

Size and Scale of the Universe SIZE AND SCALE OF THE UNIVERSE

Size and Scale of the Universe WHAT IS YOUR COSMIC ADDRESS? # Street City State Country Continent Hemisphere Planet Orbit Star??

Size and Scale of the Universe REALMS OF THE UNIVERSE Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

Size and Scale of the Universe EARTH Planet comprised primarily of rock Spherical 12,700 km diameter Image Credit: NASA/JPL/GSFC

Size and Scale of the Universe SUN The star that Earth orbits Composed primarily of hydrogen and helium gas Spherical 1.39 million km diameter Image Credit: SOHO/NASA/ESA

Calculations If the room were the sun, how big would Earth be? room's diameter (10 m) sun's diameter (1,390,000 km) = x Earth's diameter (12,700 km) 0.0914 m = 9.14 cm diameter (a wiffle ball)

Size and Scale of the Universe THE SOLAR SYSTEM Image credit: NASA/JPL-Caltech/R. Hurt Image credit: NASA Image credit: NASA Mostly distributed in a flat disk Heliosphere: The boundary between the Solar Wind (constant wind of charged gas from the sun) and interstellar space 8 planets, several dwarf planets, thousands of asteroids, and trillions of comets and meteoroids

Calculations If the room were the solar system, how big would the sun be? room's diameter (10 m) solar system (3.0 10 10 km) = x sun's diameter (1.39 10 6 km) 0.000463 m = 0.46 mm diameter (a grain of salt)

Calculations If the room were the solar system, how big would Earth s orbit be? room's diameter (10 m) solar system (3.0 10 10 km) = x Earth's orbit (3.0 10 8 km) 0.1 m = 10 cm diameter (a roll of masking tape)

Calculations If the room were the solar system, how big would Earth be? room's diameter (10 m) solar system (3.0 10 10 km) = x Earth's diameter (12, 700 km) 0.000004 m = 4 μm diameter (a microscopic bacteria)

Size and Scale of the Universe Image credit: Andrew Colvin THE SOLAR NEIGHBORHOOD Region of the Galaxy within about 20 lightyears of the Sun (40 light-years diameter) 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)

Calculations If the room were the solar neighborhood, how big would the solar system be? room's diameter (10 m) solar neighborhood (40 ly) = x solar system (3.2 10 3 ly) 0.0008 m = 0.8 mm diameter (a grain of salt)

Size and Scale of the Universe THE MILKY WAY GALAXY 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 Over 200 billion stars in the Milky Way Image credit: R. Hurt (SSC), JPL-Caltech, NASA

Calculations If the room were the Milky Way Galaxy, how big would the solar neighborhood be? room's diameter (10 m) Milky Way (100, 000 ly) = x solar neighborhood (40 ly) 0.004 m = 4 mm diameter (a peppercorn)

Size and Scale of the Universe THE LOCAL GROUP (OF GALAXIES) Contains 3 large spiral galaxies (Milky Way, Andromeda(M31), 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

Calculations If the room were the Local Group, how big would the Milky Way be? room's diameter (10 m) Local Group (6.5 10 6 ly) = x Milky Way (100, 000 ly) 0.154 m = 15.4 cm diameter (a small paper plate)

Size and Scale of the Universe THE LOCAL SUPERCLUSTER About 130 million light-years across Huge cluster of thousands upon thousands of galaxies Clusters and groups of galaxies are gravitationally bound together, but spread away from each other as the Universe expands Roughly pancake shaped Image credit: Andrew Colvin

Calculations If the room were the Local Supercluster, how big would the Local Group be? room's diameter (10 m) Local Supercluster (1.3 10 8 ly) = x Local Group (6.5 10 6 ly) 0.5 m = 50 cm diameter (an XL pizza)

Calculations If the room were the Local Supercluster, how big would the Milky Way be? room's diameter (10 m) Local Supercluster (1.3 10 8 ly) = x Milky Way (100, 000 ly) 0.008 m = 8 mm diameter (width of a paper clip)

Size and Scale of the Universe THE UNIVERSE (THE OBSERVABLE PORTION) Great walls and filaments of galaxy clusters surrounding voids containing no galaxies At least 100 billion galaxies in the Universe (probably) Image Credit: G.L. Bryan, M. L. Norman, UIUC, NCSA, GC3 Surveys of galaxies reveal a web-like or honeycomb structure to the Universe Computer simulations show the Cosmic Web Image Credit: Dr Chris Fluke, Centre for Astrophysics and Supercomputing, Swinburne University of Technology

Size and Scale of the Universe THE UNIVERSE (THE OBSERVABLE PORTION) The Observable Universe is currently about 91 billion lightyears across There could be (and likely is) much more beyond that, but we cannot see it from this point in spacetime Image Credit: Springer et al (2004)

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 Sun Solar System Solar Neighborhood Galaxy Local Group (of galaxies) Local Supercluster Universe 1.27x10 4 1.4x10-9 1 salt grain (0.1 mm) 1.39x10 6 1.5x10-7 1.09x10 2 marble (1.09 cm) 3.0x10 10 3.2x10-3 2.34x10 6 football stadium (234 meters) 3.78x10 14 4.0x10 1 3.0x10 10 ~ size of Moon (3,480 km) 9.46x10 17 1.0x10 5 7.5x10 13 5.4 Suns (7.5 million km) 6.15x10 19 6.5x10 6 4.8x10 15 orbit of Mars -diameter (~3 AU) 1.2x10 21 1.3x10 8 9.7x10 16 orbit of Neptune -diameter (~60 AU) 8.6x10 23 9.1x10 10 6.8x10 19 Oort Cloud-radius (48,000 AU or 0.76 ly)

Calculations If the room were the observable universe, how big would the Local Supercluster be? room's diameter (10 m) observable universe (9.1 10 10 ly) = x Local Supercluster (1.3 10 8 ly) 0.014 m = 1.4 cm diameter (a marble)

Calculations If the room were the observable universe, how big would the Local Group be? room's diameter (10 m) observable universe (9.1 10 10 ly) = x Local Group (6.5 10 6 ly) 0.0007 m = 0.7 mm diameter (a grain of salt)