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The Eighth Sphere

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Recently I finished reading a book about the life of Copernicus, titled "A More Perfect Heaven" by Dava Sobell. This got me enthusiastic enough to get the Copernicus book "Derevolutionibus" down from my library shelf and to start reading it.

In the Ptolemaic System there are eight spheres. The Earth is at the center of the universe and the Sun, Moon, and planets are each in a sphere surrounding the Earth and it is the motion of each of these spheres that yeilds the apparent motion of objects in our sky.

The eighth sphere is the stars. Copernicus rightly points out that the eighth sphere while being the most distant is the one that has to rotate around the Earth the most rapidly, and that this makes no sense. The eighth sphere would have to make one complete rotation every sidereal day.

In the 1500's no one knew the scale of the solar system and even the scale they did have for the Sun and the Moon were wrong. However Copernicus was on to something here, the rapid rotation of the eight sphere was complete nonsense.

Given what astronomers would figure out 182 years after Copernicus published, the movement of the eighth sphere would have to be faster then the speed of light. This would happen somewhere out near the orbit of Neptune which is a planet unknown until the middle 1800's.

We still use language like this everyday which I deem to be archaic. Language that limits our ability to think about the world. For example we refer to "Sunrise" or "Sunset" when in to be factual we should be saying horizon set and horizon rise. It is the Earth that is moving not the Sun or the Moon as it appears to us. Copernicus was right to point out how relative these apparent motions are.

We still use the words "Up" or "Down" when that only has local meaning on a spherical Earth. There is in reality no such thing as up or down, there is only Out or. Some of us compound the error by saying that the heavens are out there.

If we learn nothing more from Copernicus then one message we should take away from him that we are in the heavens. The Earth is a celestial body that moves, it is in the heavens. Conversely if you point to local down you are not pointing to Hell, you are pointing towards the stars because they are all around us.

My favorite revolution (Copernicus is where we inherited our modern meaning for the word revolution) is the discovery of the Universe beyond our local medium sized galaxy The Milky Way. This was in 1925 when Edwin Hubble discovered Chepheid Variables in Andromeda Nebula establishing that these smudges of light in our night sky were objects like our galaxy but external to it. By the early 1930's the red shift had established the expnading universe and the Big Bang theory had been put forward.

Our modern conception of a vast expanding universe finite in time was established by Hubble only 88 years ago. I still think a majority of our fellow citizens mind set wise have not caught up with the Copenican Revolution let alone with a Hubble Universe that is observable only out to 13.78 billion light years.

Let me finish with a story about how my personal mental universe changed this week and we as a species got demoted yet once again. I was watching a show on galaxies on TV when they started discussing the relative sizes of galaxies. It was then I first heard of a new champion candidate for the largest galaxy in the universe.

Just for scale I will tell you our Milky Way Spiral Galaxy is a pancake shaped object composed of from 200 to 400 billion stars approximately 100 thousand light years in diameter. It is no more then a few thousand light years thick out where we are about one third of the way from the nucleus or the center.

Andromeda Galaxy our neighboring sister galaxy is located some 2.5 million light years away is about twice the size of our galaxy according to the astronomers. You can throw in the large and Small Magellanic Clouds which we do not see from the northern hemisphere but they are dwarf galaxies about 160 thousand light years distant.

I used to tell people the local champion for large galaxy was the Eliptical Giant M-87 in the Virgo Cluster. For comparison it is composed of more then a trillion stars and orbited by more then 1,000 globular clusters. Our own galaxy has only 150 some known globular clusters in orbit around it. M-87 is about some 40 million light years distant.

Then I found out about IC-1101 which is now considered the largest known galaxy in the universe. It is rather harder to observe being a 15th magnitude member of the Abell Galaxy Cluster 2029 in the constellation Serpens. It is so dim because it is one billion light years distant.

IC-1101 is 6 million light years in diameter. It is thought to contain about 100 trillion stars. If you moved IC-1101 to our neighborhood our Milky Way Galaxy and Andromeda Galaxy with the intervening 2.5 million light years of space between them could safely fit inside this massive giant with room to spare.

I can not observe IC-1101 with my 12 inch SCT, it doesn't have enough light gathering power. I have a friend with a light bucket Dobsonian Telescope, a 17.5 inch I think which may be able to show us this distant galaxy. If we can observe it I will update this blog next month to let you know.

So this is what I mean by the eighth sphere, it is the stars and all that is contained within. That would include us, the solar system and everything we can know about. In truth it is the First and only Sphere, our amazing Universe.

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