CONTINUED FROM “CONTEXT, PERSPECTIVE, AND TIME FRAMES – COSMOLOGY 1 of 2”
We know that the Milky Way galaxy is one of about 225 billion galaxies in the “observable universe.”
Why do we say the “observable universe?”
Because we exist on one of the spiral arms of the Milky Way galaxy.
When we look out, our vision is obscured by dust, gases, and billions of solar systems.
And billions of galaxies have moved so far away from us that we will never see them.
It is estimated that there are trillions of galaxies and dwarf galaxies in the universe.
What’s a “dwarf galaxy?”
A dwarf galaxy may have only several billion solar systems while a typical galaxy has hundreds of billions of solar systems.
The nearest large galaxy is Andromeda which contains about a trillion solar systems.
To get a sense of the unimaginable, incomprehensible, and unfathomable size of the universe, imagine that we travelled at the speed of light from our galaxy, the Milky Way, to this nearest large galaxy, Andromeda.
We would have to travel 186,000 miles per second, for 2,500,000 years to reach Andromeda.
Think about that: 186,000 miles a second for 2,500,000 years to get to the nearest large galaxy of trillions of galaxies.
If travelling at 186,000 miles a second for 2,500,000 years amounts to an incomprehensible distance for you – as it should! – you will find out shortly that in the scale of the universe that it is irrelevant. It’s a tiny hop.
The largest galaxy in the observable universe is IC1101 which has 100 trillion solar systems.
IC1101, with 100 trillion solar systems, appears on the right side of the graphic above.
In size comparison, it makes the Milky Way galaxy appear to be a tiny dot.
The Milky Way Galaxy, expanded as shown, appears in the upper left of the graphic.
As previoulsy noted, the Milky Way Galaxy has an estimated 200 to 400 billion solar systems.
One of the 200 to 400 billion solar systems is ours, which appears to the right of Milky Way Galaxy.
Our solar system, as we know, has eight planets; one of the smallest ones is ours, Earth.
Recall that to travel across the Milky Way Galaxy, at 186,000 per second, would take 100,000 years.
To travel across IC1101, at 186,000 miles per second, would take nearly four million years.
The largest galaxy in the observable universe, albeit without the largest number of solar systems, is Alcyoneus.
Travelling at the speed of light, 186,000 miles per second, would require 100,000 years to cross the Milky Way Galaxy, nearly 4,000,000 years to cross the IC1101 Galaxy, and nearly 16,000,000 years to cross the Alcyoneus Galaxy!
The universe is organized into clusters and superclusters of galaxies.The Milky Way exists in a cluster of about 54 galaxies known as the Local Group.
Within the local group, to travel from the Milky Way Galaxy (in red) to the nearest large galaxy, Andromeda, travelling at 186,000 miles per second, would take 2,500,000 years.
The Local Group is 10 million light-years wide.
We would have to travel 186,000 miles a second for 10 million years to cross it!
The Local Group sits on the edge of a super cluster by the name of Virgo.
Super clusters are the largest known structures in the universe.
Recall that the Local Group, which appears as a tiny dot in the Virgo Supercluster, is ten million light years wide, i.e., it would ten million years of travel at 186,000 miles per second to cross the Local Group.
Virgo, with thousands of galaxies, is hundreds of millions of light-years wide, which is typical for superclusters.
To cross Virgo requires hundreds of millions of years of travel at 186,000 miles per second.
In the area of the Virgo Supercluster are other superclusters.
Taken together, these superclusters are known as the Local Superclusters.
There are about thirty superclusters in the group known as the Local Superclusters.
These superclusters contain thousands of galaxies and are hundreds of millions of light years wide, i.e., to cross a supercluster, one would have to travel at 186,000 per second for at least hundreds of millions of years.
The Local Superclusters and the vast distances between the superclusters amount collectively to an incomprehensible size.
As noted, there are about 30 superclusters in the Local Superclusters group.
Moving out into the universe, how many more superclusters do you think there may be. Fifty? One hundred? Five hundred?’
It’s estimated that in the observable universe, which is 4% of the universe, there are ten million superclusters!
The Local Superclusters are 30 of the 10,000,000 superclusters in the observable universe (4% of the universe)!
As an aside, the largest supercluster known in the universe is the Hercules-Corona Borealis Great Wall. It was first reported in 2013.
It’s so big that one would have to travel at 186,000 miles per second for about 10 billion years to move across it.
Galaxies, like the Milky Way, are carried along by the expansion of the universe and will move apart from every other galaxy unless they’re close enough to hold together with gravity.
Most of the galaxies in the universe, because of the Big Bang and the consequent continual expansion of the universe, are moving away from us at speeds in excess of a billion miles per hour.
The galaxies themselves aren’t moving very quickly through space, it’s space itself that is expanding and the galaxies are being carried along with it.
Space—the universe—is expanding faster than the speed of light, faster than 186,000 miles per second, faster than a billion miles per hour!
To envision this, imagine the universe as a loaf of raisin bread baking in the oven.
The rising dough is the universe expanding.
The raisins (galaxies) move with the rising dough.
Note that the raisins (galaxies) move outward and away from other raisins (galaxies) as the bread (the universe) rises and expands.
Scientists and physicists are now pondering the probability that there are many more universes, i.e., a multiverse.
Let’s review all of this briefly.
In general terms, our universe consists of clusters and super clusters of galaxies.
These galaxies contain billions and hundreds of billions of solar systems.
Planets, like ours, orbit stars.
Moons orbit some of these planets.
We exist on a planet, Earth, orbited by a moon.
Our planet and its moon orbit a star, the Sun, at 65,000 miles per hour.
The Sun, along with all of the bodies in our solar system, orbits the Milky Way galaxy at 600,000 miles per hour.
The Milky Way galaxy, with its 200 to 400 billion solar systems (stars, planets, moons, etc.) travels outward among other galaxies with the expansion of the universe at speeds in excess of a billion miles an hour — faster than the speed of light.
This is the incredible system in which we exist on a tiny planet, Earth, a mere speck on the blueprint of existence.
We are one of countless life forms trying to survive on this speck of a planet.
What other life forms are trying to survive on this planet?
We have entire animal and plant kingdoms trying to survive.
We are one of about 5,500 species of mammals.
We have feathered creatures known as birds.
We have creatures with gils, fish, that swim in the water.
We have scaley-skinned creatures known as reptiles.
We have creatures born in the water with gils, then develop lungs and can also live on land: amphibians.
We have creatures with more than four jointed legs called arthropods (insects, spiders, crustacians such crabs and prawns, myriapods such as centipedes and milipedes).
Then, we have all the water- and land-based plants.
All of these life forms are trying to survive on this tiny planet in a very narrow and fragile habitable band in our solar system that enables life to exist.
A solar system that is one of an estimated 200 to 400 billion solar systems in the Milky Way Galaxy, which is one of trillions of galaxies in a universe which may be one of countless universes in the multiverse.