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A Model of the Cosmos

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Written by
Terrence Jacobs
Contributor to Britannica.com
Terrence Jacobs
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Solar system illustration. (Sun; planets)
© matamu/Fotolia

Sometimes it’s hard to get a handle on the vastness of the universe. How far is an astronomical unit, anyhow? In this list we’ve brought the universe down to a more manageable scale.

  • Earth

    View of the Earth as seen by the Apollo 17 crew traveling toward the moon, 1972. This image and others like it captured whole hemispheres of water, land and weather. This photo was the first view of the south polar ice cap. Blue Marble 1972.
    EarthThe planet Earth.
    NASA

    The universe is a big place, but let’s cut it down to size by making the Earth the size of a Ping-Pong ball. On that scale it would be placed 500 yards (460 meters) from the Sun.

  • Sun

    1 July 2002: The Solar and Heliospheric Observatory (SOHO) satellite reveals a massive solar eruption more than 30 times the Earth's diameter. The eruption formed when a loop of a magnetic field over the surface of the Sun trapped hot gas.
    imaging using ultraviolet lightThe Sun as imaged in extreme ultraviolet light by the Earth-orbiting Solar and Heliospheric Observatory (SOHO) satellite. A massive loop-shaped eruptive prominence is visible at the lower left. Nearly white areas are the hottest; deeper reds indicate cooler temperatures.
    NASA

    The Sun would be a little over 14 feet (4 meters) in diameter, about the size of a large gazebo.

  • Moon

    Near side of the Earth's Moon, photographed by the Galileo spacecraft on its way to the Jupiter system on December 7, 1992. The dark areas are impact basins: Oceanus Procellarum (left), Mare Imbrium (centre left), Mare Serenitatis and MareTranquillitatis
    Moon

    The familiar near side of Earth's Moon, photographed on December 7, 1992, by the Galileo spacecraft on its way to Jupiter. Two primary kinds of terrain are visible—the lighter areas, which constitute the heavily cratered and very old highlands, and the darker, roughly circular plains, traditionally called maria, which are relatively young lava-filled impact basins.

    Among the maria are (from left) the crescent-shaped Oceanus Procellarum near the left limb, the large, almost perfectly circular Mare Imbrium, or Imbrium Basin (with the crater Copernicus a bright dot at its lower margin), Mare Serenitatis immediately to the right of Imbrium, Mare Tranquillitatis to the lower right of Serenitatis, and Mare Crisium, isolated near the right limb. Another bright crater, Tycho, stands out at the bottom left of the image.

    NASA/JPL/Caltech (NASA photo # PIA00405)

    On this scale the Moon would be a marble 4 feet (1.2 meters) from Earth.

  • Mercury

    Photo mosaic of images of Mercury taken from 125,000 miles away by Mariner 10 spacecraft in 1974.
    MercuryPhoto mosaic of Mercury, taken by the Mariner 10 spacecraft, 1974.
    NASA/JPL

    The planet Mercury would be the size of a large marble 2 American football fields away from the Sun.

  • Venus

    Ultraviolet image of Venus' clouds as seen by the Pioneer Venus orbiter; February 26, 1979.
    VenusVenus photographed in ultraviolet light by the Pioneer Venus Orbiter (Pioneer 12) spacecraft, February 26, 1979. Although Venus's cloud cover is nearly featureless in visible light, ultraviolet imaging reveals distinctive structure and pattern, including global-scale V-shaped bands that open toward the west (left). Added color in the image emulates Venus's yellow-white appearance to the eye.
    NASA/JPL

    Venus would approximate a Ping-Pong ball placed 375 yards (340 meters; slightly less than 2 blocks) from the Sun.

  • Mars

    Global image of "homey" Earthlike Mars (Tharsis side) with wispy clouds, taken from Mars Global Surveyor, April 1999.
    MarsAn especially serene view of Mars (Tharsis side), a composite of images taken by the Mars Global Surveyor spacecraft in April 1999. The northern polar cap and encircling dark dune field of Vastitas Borealis are visible at the top of the globe. White water-ice clouds surround the most prominent volcanic peaks, including Olympus Mons near the western limb, Alba Patera to its northeast, and the line of Tharsis volcanoes to the southeast. East of the Tharsis rise can be seen the enormous near-equatorial gash that marks the canyon system Valles Marineris.
    NASA/JPL/Malin Space Science Systems

    Mars would be a gumball sitting 3 ¼ blocks from the Sun.

  • Jupiter

    Jupiter, the fifth planet from the Sun and largest planet in the solar system. The Great Red Spot is visible in the lower left. This image is based on observations made by the Voyager 1 spacecraft in 1979.
    JupiterJupiter, the fifth planet from the Sun and largest planet in the solar system. The Great Red Spot is visible in the lower left. This image is based on observations made by the Voyager 1 spacecraft in 1979.
    Photo NASA/JPL/Caltech (NASA photo # PIA00343)

    Jupiter would be a large beach ball situated 1.5 miles (2.4 kilometers) from the Sun.

  • Saturn

    Saturn, showing an Earth-sized storm in its northern hemisphere. Such large storms are relatively rare on Saturn, which compared with Jupiter has a generally less turbulent atmosphere. Image based on observations made by the Hubble Space Telescope, Dec.1
    SaturnSaturn, showing an Earth-sized storm (light-coloured patch) in its northern equatorial region, in a composite image made from observations with the Hubble Space Telescope on December 1, 1994, more than two months after the storm's discovery. Large storms are relatively rare on Saturn, which has a less-active atmosphere than Jupiter.
    Photo AURA/STScI/NASA/JPL (NASA photo # PIA01464, STScI-PRC94-53)

    Saturn would be a slightly smaller beach ball located 2.8 miles (4.5 kilometers) from the Sun.

  • Uranus

    Hubble Space Telescope view reveals Uranus surrounded by its 4 major rings and by 10 of its 17 known satellites.Hubble recently found about 20 clouds--nearly as many clouds on Uranus as the previous total in the history of modern observations.Dated 1998.
    Hubble Space Telescope: UranusImage of Uranus captured by the Hubble Space Telescope, 1998. Visible are four of its major rings and 10 of its satellites.
    Erich Karkoschka, University of Arizona and NASA

    The planet Uranus would be the size of a cantaloupe placed 5.6 miles (9 kilometers) from the Sun.

  • Neptune

    Voyager 2 image of clouds in Neptune's atmosphere. The Great Dark Spot and its associated bright methane-ice clouds are shown slightly to the left of centre, the small dark spot is at the lower left, and the bright "Scooter" is justnorthward of the small
    clouds in Neptune's atmosphereClouds in Neptune's atmosphere, photographed by Voyager 2 in August 1989. The view is from below the planet's equator, and north is up. The Great Dark Spot (centre left) is 13,000 km (8,100 miles)—about the diameter of Earth—in its longer dimension. Accompanying it are bright, wispy clouds thought to comprise methane ice crystals. At higher southern latitudes lies a smaller, eye-shaped dark spot with a light core (bottom left). Just above that spot is a bright cloud dubbed Scooter. Each of these cloud features was seen to travel eastward but at a different rate, the Great Dark Spot moving the slowest.
    NASA/JPL

    Neptune would be approximately the size of a medium acorn squash 8.8 miles (14 kilometers) from the Sun.

  • Proxima Centauri

    Night sky showing Ursa Major stars (Big Dipper) in the northern sky. (constellation, astronomy)
    Big DipperThe stars of the Big Dipper in the constellation Ursa Major.
    © Rastan—iStock/Getty Images

    The nearest star, Proxima Centauri, has to be placed 78,450 miles (126,250 kilometers) from the Sun on this scale!

  • Milky Way Galaxy

    Milky Way Galaxy as seen from Earth
    Milky Way GalaxyThe Milky Way Galaxy as seen from Earth.
    © Dirk Hoppe

    The Milky Way galaxy would be 2,000,000 miles (3,200,000 kilometers) across!

  • Andromeda

    View of the Andromeda Galaxy (Messier 31, M31) taken by NASA's Wide-field Infrared Survey Explorer, or WISE. Blue highlights mature stars, while yellow and red show dust heated by newborn, massive stars.
    Andromeda GalaxyImage of the Andromeda Galaxy taken by NASA's Wide-field Infrared Survey Explorer (WISE). Blue indicates mature stars, while yellow and red show dust heated by newborn massive stars.
    NASA/JPL-Caltech/UCLA

    Andromeda, the nearest spiral galaxy, would be 47,000,000,000 miles (76,000,000,000 kilometers) away on this scale!

  • Light

    Plate 1: Spectrum of white light by a diffraction grating. With a prism, the red end of the spectrum is more compressed than the violet end.
    Diffraction gratingSpectrum of white light by a diffraction grating. With a prism, the red end of the spectrum is more compressed than the violet end.
    Courtesy of Bausch & Lomb, Rochester, N.Y.

    The speed of light (in reality 186,282 m/sec) would be 2.1 miles per hour (3.4 kilometers per hour).