How Big Is The Solar System?

[JustNotCricket]

I have made a small model of the solar system 10cm across with the sun in the middle and Neptune furthest away. Now I want to put it in a box to show how far away the next stars will be.

How big should this box be?

[LazyGun]

Massive.

Cannot calculate the dimensions - although others here probably could, but take a gander at this article to give you a proper sense of scale - it talks inches and paces and yards, but you will probably get the idea....

http://www.noao.edu/education/peppercorn/pcmain.html

[jim360]

About 890 metres, I think.

Neptune is 4,500,000,000 km from the Sun. The nearest Star is 4.24 light-years away, when a light-year is 9,500,000,000,000 km roughly. This makes that star about 8,900 times further away from the Sun than Neptune is, so that 8,900*10cm = 890m.

So you'll need a pretty big box.

The distance to the edge of the Solar System depends just a little on what source you consult, but could be anything between 120 times the distance between earth and Sun) and 100,000 times that distance.

[dsimiller]

Hi,
I heard about someone else who,like you made a scale model of Solar System,and asked the same question.Some guy (a professor I think) told him the nearest star,to his scale,would be thousands of miles distant,about where Cape Town would be.It certainly brings home the vast distances involved here.

[Bazile]

This reminds me of that episode of Porridge , where Fletcher and Godber wants to steal something from the office ( exam paper i think it was ) .

They employ the ruse of pretending that they are modelling in scale the distances of the planets in the solar system , to get Mr Barrowclough out of the office ..

Do you recall the episode ?

[JustNotCricket]

@all replies, thank you, keep them coming.

@Everyone. Any more thoughts on modelling our solar system and the nearest stars with a reasonable scale will be very welcome.

@LazyGun - thank you. This article gives the sort of information I am looking for. The author really sticks to one scale which is useful for keeping things clear. It gets close to answering my question.
@jim360 - thank you. I like your mathematical approach. Given the idea that my model is circular and that the full orbit of Neptune is modelled the orbit is represented by a 5cm radius so I can halve the distance to the next star to 445m. This is still too big for my model. If I reduce my model of the solar system to 1cm then I am down to 45m. I have a room which is about that long. I put the solar system onto an old half penny and I take it into the middle of the room and suggest this is the solar system in space. Then I will have to move to one corner of the room and imagine seven similar rooms corners meeting at that point to suggest that the nearest star is in one of the furthest corners. Now, I need to look in three dimensions. Which other stars are nearest to ours and where are they in respect to our solar system. Will we find ourselves near one star and no others. Will we be surrounded by stars that are about the same distance from us. Or will we be close to the one and a number of others in one direction and much further from any in the other directions?

@dsimiller - thank you too. It is only by trying to compare these sorts of distances that we can get our heads around the light-years that make so little sense. Discussing astronomical ideas with colleagues we tried to envisage a life-sustaining planet which might be too large to circumnavigate in a lifetime. We should feel sorry for ourselves realising our own short comings whilst the insects for which this concept might be true probably have no interest in such concepts.

@Everyone. Any more thoughts on modelling our solar system and the nearest stars with a reasonable scale will be very welcome.

[JustNotCricket]

@Bazile - I remember Porridge ("I read a book once - green it was." if I remember correctly). I do not remember too much of it in too much detail, but I can certainly envisage how the plot you recall might have spun out.

[jake-the-peg]

The Oort cloud is believed to be one boundary of the solar system and probably extends up to a light year from the sun

http://en.wikipedia.org/wiki/Oort_cloud

To some extent there's a body of opinion that would say that the solar system of one star ends where the influence of anothe takes over and there is no real interstellar space

[jim360]

Duh: 10 cm across = 5cm radius. Whoops!

There's basically no scale on which you can capture our Solar system and the nearest stars without making it impossible to see the Solar system. If the Solar system (Sun to Neptune) were a millimetre across then Proxima Centauri is still going to be about 4.5 metres away.

Wikipedia as usual is a great resource:

http://en.wikipedia.org/wiki/List_of_nearest_stars

Which also provides this map:

http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Nearby_Stars_(14ly_Radius).svg/600px-Nearby_Stars_(14ly_Radius).svg.png

[Teddio]

I'll have a go !

1 Astronomical Unit (1 AU) = Distance from Sun to Earth
Light takes 8 minutes to travel 1 AU
Distance from Sun to Neptune = 30AU
Therefore Neptune is 4 light hours from the Sun (240 light minutes)

Nearest star (Proxima Centauri) is 4.4 light years away = 38544 light hours from the Sun

Therefore the nearest star is 38544/4 = 9639 times further away from the Sun than Neptune

Your model would therefore have to be a sphere 5cm X 9639 = 48180 cm radius (approximately 480 metres radius) or 960 metres in diameter.

In other words, a sphere of diameter approximately 1 kilometre

Does this answer seem reasonable ?

[LazyGun]

I remember that Porridge episode only too well, Bazile - one of my all-time favourites :)

Experiments like this are really interesting - it just serves to illustrate how mind-meltingly vast the distance is in space. It also, for me, gives further reason to be astonished at the size of the Sun in comparison to all the other planets.

And as Jim rightly points out, there is some debate over what defines the outer boundary of the solar system - the oort cloud is often used, but not everyone agrees...

[JustNotCricket]

It is so easy to think of space as being either somewhere full of stars and a few planets or as something big and empty. I am trying to get a real picture of how big the space around us really is, hence my original question. After that it could be a mental game of Lego to fit in all the different stars and the spaces around them. I am beginning to get a picture. And what is also clear is that this picture has not been built before in this way. Thanks again to all replies. I will read through them in closer detail before responding individually.

[jim360]

Numbers seem a bit out:

Proxima is 4.24 not 4.4 light years away, and 1 Astronomical Unit is about 8 minutes 20 seconds not 8 minutes exactly.

[jim360]

Best piece of software for this is undoubtedly Celestia. If you have the time and computing space I'd recommend downloading it. You won't get a truer idea of how vast space is than in that program.

[AB Editor]

If you are building this model for someone else's enlightenment then you might want to supplement this as well:

http://htwins.net/scale2/

(Sorry for posting this again everyone. I do think it is excellent though)

[LazyGun]

Thats a nice scaling programme, Ed. I love the inclusion of "Minecraft World" :)

[trt]

I wonder where it all ends, if ever?

[LazyGun]

@ the glass wall of the fish tank,trt - go to fast and that will give you a nasty bruise when you collide with it :)

[beso]

I remember as a kid my brother and sister and I made a model of the solar system in the back yard. We were astounded by how many times we had to drop the scale as we added the more distant planets.

Consider this. Although the nearest star is only four light years away our galaxy is 120,000 light years across. That dimension won't even come close fitting on the whole Earth in your model.

Clearly, the scale of the Universe is beyond any real comprehension.

[jomifl]

I've been classifying gravitational lenses on zooniverse and I get to see a lot of galaxies, I think the size of the universe is beyond human comprehension. A galaxy the size of ours that can only be seen with the hubble telescope almost fills the frame and beyond it are tiny specks that are other galaxies the same size.

[mibn2cweus]

ZOOM Zoom zoom - http://www.numbersleuth.org/universe/