Like a Grain of Sand on the Cosmic Beach: The Earth in Cosmic Perspective

By Adam J. Pearson

Fig 1.1 – The Universe. Each white dot represents a Supercluster of galaxies. 

Today, I started reading an amazing astronomy textbook entitled The Cosmic Perspective. The opening of the book really put the size of the Earth in cosmic perspective. If you think the Earth is the center of the universe and tremendously important in a universal sense, consider this:

In the vast universe, there are countless ‘superclusters’ in which groups of thousands upon thousands of galaxies are tightly packed together together. Superclusters are giant structures that loosely form giant chains and sheets that resemble strands in a giant cosmic spiderweb.

Between the vast superclusters are voids containing few, if any galaxies at all. The universe is itself “the sum total of all matter and energy, encompassing the superclusters and voids and everything within them” (The Cosmic Perspective, 4th ed., pp. 2).

Fig 1.2. – Our Neighbouring SuperclustersIn this image, you can see the Virgo Supercluster or Local Supercluster relative to the Superclusters that are located around us.  These are our cosmic neighbours, each composed of countless groups of galaxies. 

In our own Local Supercluster (also known as the Virgo Supercluster), there are even denser packs of galaxies called ‘groups’ or ‘galaxy clusters‘ (groups of galaxies with more than a few dozen members). Our own Milky Way Galaxy is one among 40 other galaxies in what we call the Local Group. We call it “Local” because the galaxies in this group are located, relative to the entire universe, closest to ‘home.’

Fig. 1.3 – Inside the Virgo Supercluster or Local Supercluster – This is a diagram of the inside of the Virgo Supercluster. Each dot represents a group of galaxies. The Local Group is the group within which our own Milky Way Galaxy is located.  

Fig 1.4 – Inside the Local GroupThis image depicts the inside of the Local Group of galaxies and the galaxies immediately located around our own Milky Way.  All of the above images are from The Atlas of the Universe

Within the Milky Way, there are more than 100 billion stars of which our Sun is but one. Our own solar system orbits this relatively small star, the Sun. This solar system is located a little over halfway from the galactic center to the edge of the Milky Way’s galactic disk.

Fig. 1.5 – The Milky Way GalaxyThis is an artist’s rendition of the Milky Way Galaxy with the position of our Sun identified. 

Fig 1.6 – The Orion Arm of the Milky Way GalaxyThis is an image of the Orion Arm of the Milky Way Galaxy in which our Sun is located. Notice how small of a dot our Sun is within the larger arm. 

Within the solar system, our home planet, the Earth, orbits the Sun. It is the fifth-smallest planet in our solar system. Upon this planet, we, human beings, move like tiny ants in the great, unfathomably large vastness of the universe.

Upon this small rock, we live, and move, and have our being.  We visit coffee shops and go to school and work in offices and get into arguments and cry and laugh and smile and live and die.  And all around us, billions of galaxies whirl, each containing billions of stars with billions upon billions of planets and moons orbiting them.  Our home, the Earth, is like a tiny grain of sand on a gigantic cosmic beach.  And we are like infinitesimally small bacteria moving upon that tiny grain of sand.

Fig. 1.7 – The EarthOur home planet, the fifth-smallest planet in our solar system.

Fig 1.8. – An Aerial View of Montreal – the city within which I presently sit, 13.75 ± 0.13 billion years after the Big Bang, 4.54 billion years after the formation of the Earth, 23 years after my birth, writing the article that you are now reading.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s