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Step 4: The Realm of Galaxies
Now let's switch scales one last time, and shrink the entire continent-sized galaxy down
to 2 inches:
* Size of Sun and Stars - Individual stars are invisible, smaller than atoms, at this
2-inch scale. The bright specks in this galaxy image come from the added light of thousands
of stars. * Location of Sun - 1/2 inch (about 1 cm)
from edge of 2-inch galaxy image * Distance to Andromeda Galaxy, the Nearest
Spiral - 5 feet (1.5 m) at this scale - hold the two galaxy images apart with your arms
spread wide. * Distance to Farthest Galaxies Observed by
Hubble Telescope - 4 miles (6.5 km). In the Hubble image of the "Ultra Deep Field" almost
all the fuzzy spots of light are distant galaxies. Because light takes time to travel through
space, we see the farthest of these not as they are now, but as they were 12 billion
years ago. * Size of the Whole Universe? - No one knows...it
could be infinite. * Light Travel Time - It would take 100,000
years for a beam of light to cross our galaxy and 2.5 million years for light to travel
from the Andromeda Galaxy to us.