unit 1 size and scale - ms. wahl...

Size and Scale of the Universe

SIZEANDSCALEOFTHEUNIVERSE

WHAT IS YOUR COSMIC ADDRESS?


# Street

City

State

Country

Continent

Hemisphere

Planet

Orbit

Star?

…?

…

…

…

…

REALMS OF THE UNIVERSESize and Scale of the Universe

Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

EARTHSize and Scale of the Universe

• Planet comprised primarily of rock

• Spherical • 12,700 km

diameter

Image Credit: NASA/JPL/GSFC

SUNSize and Scale of the Universe

• 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)

THE SOLAR SYSTEMSize 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 • Heliosphere: The boundary

between the Solar Wind (constant wind of charged gas from the sun) and interstellar space

Image credit: N

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Image credit: N

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CalculationsIf the room were the solar system, how big would the sun be?

room's diameter (10 m)solar system (3.0×1010 km)

=x

sun's diameter (1.39×106 km)

0.000463 m = 0.46 mm diameter(a grain of salt)

CalculationsIf the room were the solar system, how big would Earth’s orbit be?

0.1 m = 10 cm diameter(a roll of masking tape)


=x

Earth's orbit (3.0×108 km)

CalculationsIf the room were the solar system, how big would Earth be?

0.000004 m = 4 μm diameter(a microscopic bacteria)


=x

Earth's diameter (12, 700 km)

THE SOLAR NEIGHBORHOOD


• Region of the Galaxy within about 20 light-years 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)

Image credit: Andrew Colvin

CalculationsIf 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)

THE MILKY WAY GALAXYSize and Scale of the Universe

• 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

CalculationsIf the room were the Milky Way Galaxy, how big would the solar neighborhood be?

0.004 m = 4 mm diameter(a peppercorn)

room's diameter (10 m)Milky Way (100, 000 ly)

=x

solar neighborhood (40 ly)

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

CalculationsIf the room were the Local Group, how big would the Milky Way be?

0.154 m = 15.4 cm diameter(a small paper plate)

room's diameter (10 m)Local Group (6.5×106 ly)

=x

Milky Way (100, 000 ly)

THE LOCAL SUPERCLUSTERSize and Scale of the Universe

• 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

CalculationsIf the room were the Local Supercluster, how big would the Local Group be?

0.5 m = 50 cm diameter(an XL pizza)

room's diameter (10 m)Local Supercluster (1.3×108 ly)

=x

Local Group (6.5×106 ly)

CalculationsIf the room were the Local Supercluster, how big would the Milky Way be?

0.008 m = 8 mm diameter(width of a paper clip)

room's diameter (10 m)Local Supercluster (1.3×108 ly)

=x

Milky Way (100, 000 ly)

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: Dr Chris Fluke, Centre for Astrophysics and Supercomputing, Swinburne University of Technology

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”


THE UNIVERSE(THE OBSERVABLE PORTION)

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


RealmActual 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

1.27x104 1.4x10-9 1 salt grain (0.1 mm)

1.39x106 1.5x10-7 1.09x102 marble (1.09 cm)

3.0x1010 3.2x10-3 2.34x106 football stadium(234 meters)

3.78x1014 4.0x101 3.0x1010 ~ size of Moon(3,480 km)

9.46x1017 1.0x105 7.5x1013 5.4 Suns (7.5 million km)

6.15x1019 6.5x106 4.8x1015 orbit of Mars -diameter(~3 AU)

1.2x1021 1.3x108 9.7x1016 orbit of Neptune -diameter(~60 AU)

8.6x1023 9.1x1010 6.8x1019 Oort Cloud-radius (48,000 AU or 0.76

ly)

CalculationsIf the room were the observable universe, how big would the Local Supercluster be?

0.014 m = 1.4 cm diameter(a marble)

room's diameter (10 m)observable universe (9.1×1010 ly)

=x

Local Supercluster (1.3×108 ly)

CalculationsIf the room were the observable universe, how big would the Local Group be?


room's diameter (10 m)observable universe (9.1×1010 ly)

=x

Local Group (6.5×106 ly)

unit 1 size and scale - ms. wahl...

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