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Astro Analogy's


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Hi all,

I struggle to comprehend the sheer size and scale of our solar system, not to mention our galaxy and the universe. 

Consequently, I am a big fan of analogy's ... how many days it would take to travel to the moon in a car at 60mph ... how many tons of salt you would need to make a model of our galaxy ... that sort of thing. 

Does anyone have a favourite analogy that they don't mind sharing? 

Thanks,

Steve :)

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Can we go small as well??

A slice of cake, one millimeter long, is divided up into 1,000 pieces. Each piece is a MICRON. A typical paramecium (tiny, single celled fresh water animal) is around 2 microns long. To see this in a drop of water, you would have to enlarge the water to 12 metres across. If you wanted to see an atom, though, you would have to enlarge the droplet to 24 KILOMETERS across.

An atom is one ten-millionth of a millimetre long.

To put it another way, an atom to one millimetre is the same as a single sheet of paper to the Empire State Building's height.

:shock:

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Those of you that d/l the Hubble AVI's will have seen the presenter talking about the number of galaxies in the universe exceeding the number of grains of sand on all the beaches on the entire planet.

And then some!!!

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  • 2 weeks later...

When I show galaxies in the Virgo Cluster, some 60 million ly away, I like to say that when the light you're seeing now left there, the dinosaurs were still the dominant lifeform on Earth. And that's just one. 8)

Now that's a cool one!

8)

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  • 1 year later...

Now that we have much more members I thought I'd wake this thread up and see how far it runs.

To save you going back to the beginning, it starts with:

I struggle to comprehend the sheer size and scale of our solar system, not to mention our galaxy and the universe.

Consequently, I am a big fan of analogy's ... how many days it would take to travel to the moon in a car at 60mph ... how many tons of salt you would need to make a model of our galaxy ... that sort of thing.

Does anyone have a favourite analogy that they don't mind sharing?

Thanks,

Steve :wink:

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"The Amateur Astronomer's Guide to the Celestial Sphere" contains two examples:


  • [li]Assuming 100 billion galaxies and 200 billion stars per galaxy implies 20,000 billion billion stars in the Universe.
    Assuming beaches are 100 metres wide and 10 metres deep and given that there are about 1 million kilometres of beaches on Earth, the volume of sand is about 1,000 billion cubic metres. If each grain of sand is 0.25 cubic mm and "pack" with 70% efficiency, there are 175 million grains of sand in each cubic metre and hence 175 billion billion grains of sand on all the beaches on Earth. Therefore, there are as many stars in the Universe as there are grains of sand on all the beaches of over 100 Earths!
    Does anyone believe we are on the only planet where life has evolved?
    [/li]
    [li]The nearest stars are in the Alpha Centauri system at 4.3 light years away. That is 4.3 * 365.25 * 24 * 60 * 60 * 186,000 miles away ie about 25 thousand billion (25 trillion) miles. Our fastest spacecraft to date travel at 70,000 miles per hour, therefore it would take one of them 25 trillion / (70,000 * 24 * 365.25) years to get there ie about 39,000 years.
    Human recorded history is only about 6,000 years. Perhaps this explains why we have not encountered life from elsewhere in the Universe.[/li]

Apologies for any mistakes I may have made in transposition but if you don't agree with the numbers above, take it up with the book's author William Millar.

I can whole-heartedly recommend the book for anyone trying to understand the coordinate systems, motions of the sky etc.

Mike

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This is not an analogy as such, but merely a personal sense of our own place in the vast out there, some of which we have the priviledge of seeing. We are nearing the time, at least we think we are nearing the time, when instrumental eyes will allow us to go back to the beginning of the birth of the universe. What then? Will that knowledge change anything as far as our place is concerned. ? I for one doubt it.

Our technical and scientific progress over the thousands of generations of man, has taken us to the brink of spreading our influence over the family of bodies encircling our own star, But, then it stops. I believe our study of the rest of the universe will continue to be a remote one.

However many science fiction devices that can be quoted as having come true, I for one do not conceive of mankind ever visiting another star system. What man will be able to touch, lies entirely within the influence of his own sun.

So, I suppose this can be termed analagous, in as much as that man can, and will always be able to see the universe,

but he will never be able to infuence it.

Now these are purely my own opinions, and nothing other than an understanding as I personally see it

Also, please let no one attache any religous connotation to it, there isn't one.

Religion and politics have no place here, we all know that.

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:wink: Nice response Steve!

Here's some....

The speed of light is 7 times around the Earth in one second.... with this in mind....

-Travelling at the speed of light, it would take longer than a human lifetime to escape our own galaxy (shortest route) !

-Travelling at the speed of light it would take just over an hour to reach Saturn from Earth and 37,009 hours to reach our nearest star, Proxima Centauri !

-Traveling in a plane at 500mph it would take 203 years to reach Saturn from Earth :shock: now thats what I call a long haul flight!

Matt

ps sorry I got loads of these!

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-Traveling in a plane at 500mph it would take 203 years to reach Saturn from Earth :shock: now thats what I call a long haul flight!

Do they do inflight meals and are the drinks free? :wink:

I'll wait for faster than light travel. It's just around the corner you know. They are just having problems finding the right corner,that all!

CW

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I'M PROBABLY WRONG ON THIS ONE BUT IF I AM I'M SURE SOMEONE WILL PUT ME RIGHT,

I READ SOMEWHERE RECENTLY THAT THE AMOUNT OF ENERGY DISPELLED BY OUR sun (sorry) EACH SECOND WOULD EQUAL THE TOTAL AMOUNT ENERGY USED BY THE USA IN A THOUSAND YEARS.( NOTE FOR THE REST OF WORLD COMBINED IT WOULD PROBABLY A LOT LONGER :wink::cool::lol::p:evil::clouds2:)

KARLO

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I love these things :cool: Not only it amazes myself, but also it is way easier to show how BIG things in universe are, when talking to someone else 8) One thing (it may not be real analog though..) that I love is to explain people is how strong the gravity of a black hole should be if even light can't escape. I read this one somewhere in the internet I can't remember where.. :wink:

When you throw the tennis ball upwards, it goes higher every time you increase power by throwing it. but it comes back because of earths gravity. if you could throw the ball at 7miles/s (this is the "escape velosity" ), the earths gravitational field would not be able to pull it back.

So when the gravitation is bigger, it means the escape velocity is bigger. It is hard to imagine, how the gravity can reach the point, where even light, travelling at 186 000 000miles/s can not escape. It just blows everyones mind :lol:

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I think the ball would vaporize before it got 20 miles, and leave a stinking trail of burnt rubber miles into the sky.

I love to show people something like the Andromeda galaxy, and tell them the light from it left there 2.5 million years ago. When you have a fundamentalist in the crowd who thinks the Earth is 6.000 years old, you can get some sharp looks.

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I just remembered another analogy that I always liked. If a baseball were the size of the Earth, the atoms in it would be the size of grapes. That's a lot of grapes! Yum!

But, would the baseball still have 108 stitches?

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Warthog

6,000 years is a little too vague for some. In the seventeenth century, Archishop Usher went back through the Bible and calculated that the world began on October 26th 4004 BC.

More recently, various Church leaders over here have suggested that the recent bad weather is God's punishment for our wickedness.

As for analogies I always like the one about Saturn. If you had a bath of water big enough it would float in it.

Geoff

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Less of an analogy, more of my own personal proverb....

"For every quid you have in your bank account, there's £100's worth of stuff worth buying to add to your equipment collection!"

:wink:

Peonic

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Scale analogies are amazing. For instance, if our sun were represented by something the size of a golf-ball, Proxima-Centauri would be a similar sized ball a mere 2300km away. And that's right next door, cosmologically speaking! That's a golfball located at the top end of Denmark and it's nearest neighbour somewhere near Rome for us Euro folk, or about the distance from Toronto to Miami for you colonials.

Very slightly off topic but as a skeptic I love the scales of dilutions used by Homeopathic 'medicine', and it gets swiftly into astronomical numbers and analogies. Homeopaths believe water has a magic memory and remembers everything you put in it, and the more you dilute it the stronger it gets (so dont go to the toilet!). :? Their standard medicine dilutions are measured in C, where each 'C' is a x100 dilution and then the dilution is whacked off a bit of leather precisely 100 times, otherwise the magic doesn't work. The smallest solution is usually 6C, a dose of which would contain about 1 molecule of medicine in a glass of water the volume of the Earth. Your average homeopathic cold remedy is a 30C dilution, which is 1/100 of 1/100 of 1/100 time 30! This means if you wanted to actually be sure of finding one molecule of the medicine in the diluted water you'd have to have a pool the size of 30 billion Earth sized planets. :shock: For real potency they believe you should dilute up to 200C, which makes it impossible to be sure of finding a molecule of medicine as it would require more molecules of water than there are particles in the known universe. Potent stuff!

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As for analogies I always like the one about Saturn. If you had a bath of water big enough it would float in it.

I liked this analogy too, until I figured out that a tub that size would collapse under it's own gravity to become a star. :wink::cool:

The Saturn analogy I use is, that Saturn and its rings would just fit between Earth and the Moon.

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