The last in this recent series on me examining my navel!
Dear Mr. Cosmos,
Clearly, I have no idea how many letters you receive from us funny inhabitants on Planet Earth. Can’t imagine you get floods of them but then neither can I imagine that this is the first one you have ever received.
Why can I not imagine this is to be your first? Simply, because us funny folk on this incredible planet of yours have been around for quite a while. I mean that over in that country we folk call Israel there has been found evidence of “control of fire by humans nearly 790,000 years ago.”
Just realised that me saying “quite a while” and writing of “790,000 years ago” will be utterly meaningless, in terms of scale, to how you describe your past. Just as it is utterly meaningless for me to contemplate that in cosmological terms the ‘Big Bang”, generally recognised as the start of your Universe, was, give or take, some 13.8 billion years ago.
I wish I could really get an idea of what a million years feels like, let alone a billion years. Ah well!
Let me stay with this notion of stuff being meaningless.
My dear, long-time friend Dan Gomez sent me a link to an item that had been published on the Science Alert website. It was about how the NASA Hubble space telescope had recently embarked on a new mission. Or in the words of that article:
Hubble Just Revealed Thousands of Hidden Galaxies in This Jaw-Dropping Photo
By Michelle Starr, September 13th, 2018
Hubble has embarked on a new observation mission: to study the farthest reaches of the Universe, using some of the most massive objects in the Universe – galaxy clusters.
And this newly released picture shows how.
At the centre is Abell 370, a cluster of a few hundred galaxies located around 4 billion light-years from Earth. And arrayed around it, never seen before, are thousands of galaxies, out even farther in the depths of space.
The reason we can see them now is because of Abell 370. All those hundreds of galaxies, clustered so close together, and the associated dark matter, create an immense field of gravity.
When the light behind that field passes through it, the gravitational force is so strong that it bends the path of the light. This creates a magnifying effect called gravitational lensing, allowing us to see objects we usually can’t.
Abell 370 is the first of these clusters.
Here is one of those photographs,
And an explanation of what we are looking at:
In the image, you can see the galaxies in Abell 370. The brightest yellowish white ones are huge, containing hundreds of billions of stars. The bluer ones are smaller, spiral galaxies, like the Milky Way, with younger populations of stars. And the dimmer, yellower galaxies are older, with ageing star populations.
The galaxies behind Abell 370 appear as smeared lines of light. The most spectacular, to the lower left of the centre, is nicknamed the Dragon (possibly for its resemblance to a Chinese dragon), with its head to the left. It’s made up of five images of the same spiral galaxy, magnified and stretched by the gravitational lens.
Mr. Cosmos, you know a little earlier I was remarking about how it is impossible to comprehend the age of the Universe. Well, dear Sir, it’s just as impossible to comprehend your distances.
Take Abell 370 out there some 4 billion light years from Planet Earth! I really wanted to have a go at understanding that distance.
First, I looked up the distance in miles that is represented by one light-year. Answer: one light year is a tad under six trillion miles.
Just one, let alone some 4 billion of them!
Next, I looked up the distance of our very familiar Big Dipper constellation. You must have heard of it? This one!
Turns out that even this very familiar sight in our night sky ranges from 78 to 123 light years away. Average that as 100 light years and, bingo, you are looking at this familiar cluster of stars that is 590 trillion miles away!
So, dear Mr. Cosmos, that puts your Abell 370 constellation about a distance that is 10 million times more distant than our Big Dipper!
I wrote above that “I really wanted to understand that distance.” In reference to how far that Abell 370 constellation truly was. My conclusion is that I will never, ever understand that distance.
Anyone able to help?
Tomorrow, Mr. Cosmos, the closing page two of my letter to you.