WWW.ASTRONOMY.COM 35of understanding the size of the universe,
let’s pretend that our spaceship could.)
In our spaceship, let’s set out from
the Milky Way Galaxy, our home. The
closest galaxy we can encounter is the
Sagittarius Dwarf Spheroidal Galaxy, a
tiny galaxy that orbits ours. If we move at
the speed of light, it would take us 70,000
years to reach this galaxy. Another way
of thinking about these enormous dis-
tances is to understand how long the
light that we now see from other galaxies
has been traveling through space to reach
us. The light from the Sagittarius Dwarf
Spheroidal Galaxy has traveled since
humans made their earliest bits of art
inside caves in South Africa. If we trav-
eled for 163,000 years in our spaceship,
we could arrive at the Large Magellanic
Cloud, our galaxy’s largest satellite.
Traveling for 200,000 years would
carry us to the Small Magellanic Cloud,
another satellite of our Milky Way. The
light you see from this galaxy tonight has
traveled through space since our earliest
human ancestors closely linked to our
species walked the African plains.
But those are dwarf galaxies that
are very close to us. The largest nearby
galaxy is the Andromeda Galaxy, which
would take us 2.5 million years to reach
in our spaceship. The light you see from
this galaxy tonight has traveled through
space since some of our earliest human
ancestors were here on Earth.
And these are just some of the galax-
ies closest to us. Traveling outward, you
would find countless examples of strange
and beautiful galaxies at all manner of
distances. These would include spirals
like IC 239, M100, M106, NGC 210, NGC
2683, NGC 2841, NGC 3310, NGC 3338,
NGC 4565, and NGC 6946. You would
encounter fields of multiple galaxies like
those in the Leo Trio (M65, M66, and
NGC 3628), M81 and M82, and the gal-
axy group Hickson 31. Some galaxies
that seem to be connected, like NGC
3314, would grow away from each other
as you approached and their visual align-
ment disappeared. You would encounter
numerous weird, distorted galaxies —
the result of interactions or disruptions
by black holes — like Arp 188, ESO 243-
49, NGC 474, NGC 660, NGC 2685,
NGC 4622, NGC 5291, NGC 7714, and
UG C 6 9 7.
You can see how enormous the cosmosis and understand that, fundamentally, it
is filled with galaxies. The Virgo Cluster
galaxies would take 50 million years to
reach in our light-speed spaceship. More
distant galaxies are arranged in clusters
and superclusters that we can see from
Earth, and some lie hundreds of millions
or billions of light-years away. Reaching
the most distant galaxies that we can see
would take us more than 13 billion years,
traveling at the speed of light.
Living our lives on this third planet
from the Sun in our solar system, it’s
easy to ignore how unbelievably
immense the universe is. But moving
farther and farther out into the universe
to explore galaxies allows us to under-
stand how the universe came to be, and
where it’s going.David J. Eicher is editor of Astronomy
and the author of 25 books on science and
history, the latest being Galaxies: Inside the
Universe’s Star Cities (Clarkson Potter, 2020).This story is adapted from Galaxies:
Inside the Universe’s Star Cities
by David J. Eicher, © 2020 Clarkson Potter
Publishers, New York.EXPLORE GALAXIES FROM HOME
Galaxies: Inside the Universe’s Star Cities by David J. Eicher (Clarkson Potter, 2020) presents
the amazing story of our knowledge of the great star systems populating the cosmos.
Inspired by Tim Ferris’ 1980 book Galaxies, the new work updates the story of what we
know about the fundamental systems of stars, gas, and dust into the 21st century.
Galaxies: Inside the Universe‘s Star Cities contains 200 color photographs and diagrams
showing and explaining the many types of galaxies and how astronomers have come to
understand key questions about them over just the last generation. Cutting-edge imagery
from the Hubble Space Telescope and many ground-based observatories helps to tell the
tale of our understanding of galaxy formation and evolution via mergers, combining small
blobs into the larger, organized structures like our Milky Way we see today. The greatest
recent images by amateur astronomers show the many spectacular forms and colors of
spirals, barred spirals, ellipticals, and others.
The book explores the subject of galaxies traveling
into the deep cosmos, from seeing the band of light
of our Milky Way overhead in your backyard to
understanding the barred spiral structure of our own
galaxy, a relatively recent discovery. We explore the
Local Group of galaxies, the Virgo Cluster, the Local
Supercluster, and the largest structures in the
universe — walls, sheets, and filaments spanning
billions of light-years.
The extensive text describes all of the most
amazing and recently discovered aspects of galaxies,
from supermassive black holes to dark matter to the
fate of our galaxy and of the universe itself.Galaxies: Inside the Universe’s Star Cities is
available online at MyScienceShop.com/GalaxiesBK