Narrative
Description of Size and Scale Poster
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This poster was produced in part to celebrate the launching of the Hubble Space Telescope. It attempts to show the relative sizes of objects in the Universe, from familiar objects at the bottom of the poster to the dim and puzzling objects at the farthest reaches of the cosmos at the top. The printed caption states: "From the orbit of NASA's Hubble Space Telescope, the Universe is observed to be richly endowed with a wide range of astronomical objects--from planet Earth to the stars, galaxies, and clusters of galaxies beyond."
At bottom right, we see Hubble, which is a spacecraft fully the size of a city bus, and space-walking astronauts, who provide a further sense of scale that children understand.
Most space vehicle activities today occur very close to the Earth, as the artistically drawn transparent cone suggests, pointing left toward the full Earth, now suspended in an imaginary glass box having dimensions approximating the diameter of our planet, namely about 13,000 kilometer(or about 8000 miles).
Earth, in turn, is only one planet within a Sun-centered Solar System that spans some 10 billion kilometers (or 6 billion miles). And our star, the Sun, is just one of about two dozen other stars within the local stellar neighborhood, whose imaginary box at middle left spans about 10 light-years. (A light-year is the distance traveled by light in a full year, namely 10 trillion kilometers, or 6 trillion miles.)
Moving to even larger scales, we see that all the relatively local stars reside in the "suburbs" of a much larger ensemble of stars, called the Milky Way Galaxy. Normal, pinwheel-shaped galaxies, such as the one in which we live, are little more than a collection of hundreds of billions of stars strewn over some 150,000 light-years.
Beyond the size of a typical galaxy, we begin to enter the truly large realms of space. This is where the mind boggles for many students--and professional astronomers alike! For, as shown in the upper left imaginary glass box, our Galaxy is just one of about twenty other galaxies spread across some 3 million light-years--a vast region known as the Local Group of Galaxies.
And, finally, maybe, at upper right are the farthest reaches of the known Universe. Note how all the huge objects within the top left box are now compressed to within virtually a single dot among many other dots (each representing numerous galaxies) at upper right. This is the domain of galaxy clusters, and perhaps clusters of clusters--a distance that reaches out to roughly 15 billion light-years.
The structure and nature of the cosmic objects residing at the limits of the observable Universe can now only be dimly perceived. This is one of the frontiers of science today--and fertile territory for scientists of the next generation to explore. Children in the classrooms of today will surely unravel some of the secrets now hidden within these distant objects that illuminate the faraway and the long ago.