The Universe on an Earthly Scale

About the universe as presented on an Earthly scale with distances of galaxies equal to distance of cities.

THE UNIVERSE ON AN EARTHLY SCALE

We have seen how our solar system would appear if charted on the surface of the earth itself; let us now consider how the universe would appear, charted in the same way.

For this we choose the scale 1 cm. = 1 light-year (10??13 km., or 0.6 x 10??13 mi.); this is equivalent to 1:10??18 (instead of 1:10??5 on the previous scale).

Once again we set off by airplane from the southernmost point of Manhattan Island, in New York, and soon we are clear of our Milky Way Galaxy, which appears as a cloud of stars about 1 km. (0.6 mi.) in diameter, centered over the Battery Park and New York harbor, some 200 meters (660 ft.) thick at the center and tapering to about 25 meters (75 ft.) near the edge.

Looking back with a powerful telescope, we might be able to discern our solar system as a tiny object 1/100 the size of a pinhead, about 200 meters (220 yd.) from the outer edge of the cloud; and within this our earth is a microscopic speck.

This sort of comparison helps us to realize clearly how small our solar system is compared with the dimensions of the known universe; in numbers, the mean distance from the sun to the outermost planet, Pluto, is about 5 light-hours (not light-years!), thus a very small fraction of our unit of scale, the light-year, which is represented by 1 cm.

Looking around again from our aircraft, we would see at about 240th Street, 20 km. from our starting point, the Andromeda Nebula, which is a galaxy of about the same size as our Milky Way, which we have just left.

Continuing our flight westward, we see galaxies, some larger some smaller, every 10 km. or so; but over the Pacific Ocean, beyond San Francisco, we reach a point that a few years ago was the furthest range of the most powerful telescope at the Mt. Palomar observatory. This point actually lies 2,000 km. (1,250 mi.) beyond the Hawaiian Islands, so 10,000 km. (6,250 mi.) from our starting point at New York, representing a thousand million (10??9) light-years. Present equipment has "enlarged" this observable universe to 10??10 light-years: on our map, 2.5 times around the earth.

Compare this enormous distance with the size of the earth, hidden as a minute part of an object itself 1/100 the size of a pinhead situated at the starting point of our journey.

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