Sizes and Distances

Jeff Root · #1 (**permalink**) 12-July-2005, 12:48 AM

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I'm making a list of relatively familiar, visually interesting
objects to represent different sizes or distances apart, as
close as possible to whole orders of magnitude multiples of
one metre.**Some examples:

Code:

1 e7**m***Earth's diameter*****1.2756 e7 m
1 e9**m***Sun's diameter*******1.392 e9**m
1 e21 m***Milky Way diameter***1 e21*****m
1 e23 m***Distance to M81******1.18 e23**m

For your reference:

1 light-year =**9.46 e15**m
1 parsec*****=**3.085 e16 m

Many interesting objects are of course at distances which are
NOT close to order-of-magnitude multiples, such as the nearest
bright star, Alpha Centauri, at about 3.8 e16 m.

Can you suggest some objects to represent other whole multiples
in the range 1 e8 m - 1 e25 m?

***-- Jeff, in Minneapolis

Edited to correct Bad error in light-year and parsec values!

A Thousand Pardons · #2 (**permalink**) 12-July-2005, 01:25 AM

Quote:

Originally Posted by Jeff Root

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Can you suggest some objects to represent other whole multiples

Code:

 
1 e2  m   Football field       1.1   e2  m
1 e3  m   Kilometer :)         1.0   e3  m
1 e8  m   Jupiter's diameter   1.43  e8  m
1 e11 m   Distance to Sun      1.52  e11 m
1 e12 m   Distance to Saturn   1.206 e12 m (close)

PS: BTW, doesn't that make the Milky Way diameter equal 1e4 lightyears? 10,000 lightyears? Shouldn't it be 100,000?
PSS:

Quote:

Originally Posted by Jeff Root

For your reference:

1 light-year = 9.46 e16 m
1 parsec = 3.085 e17 m

A light-year should be 9.46 e15 m and a parsec 3.085 e16 m, right?

Jeff Root · #3 (**permalink**) 12-July-2005, 02:01 AM

A Thousand Pardons replied to Jeff:

> A light-year should be 9.46 e15 m and a parsec 3.085 e16 m, right?

That's correct!**I made a mistake in converting from one
system to another just before posting.**I'll edit my original
post to cover up my error.**Nobody will ever know!

You guessed right that I'm also interested in smaller sizes.
A football field might be good.

Any nebulae, galaxies, or galaxy clusters that are close to
whole orders of magnitude distant?

***-- Jeff, in Minneapolis

Tobin Dax · #4 (**permalink**) 12-July-2005, 09:40 PM

I'd have to look for anything else (if I get the chance), but might it help that 1ly is about 1E16 m? I'm not sure if you two overlooked this or not, but it does mean that you're simply looking for anything that's 10^N ly in size/distance, where N is any integer.

Grey · #5 (**permalink**) 13-July-2005, 12:24 AM

Code:

 
1 e17 m   Sirius               0.81  e17 m
1 e19 m   Dumbbell Nebula      1.18  e19 m
1 e24 m   NGC 4319             0.76  e24 m
1 e25 m   Markarian 205        1.04  e25 m

NGC 4319 is probably pushing it in being close to an even order of magnitude, but I liked it because it shows up in the same Hubble field of view as the quasar Markarian 205, so I thought it was a nice contrast.

Jeff Root · #6 (**permalink**) 13-July-2005, 02:47 AM

Tobin Dax replied to Jeff:

> might it help that 1ly is about 1E16 m? I'm not sure if you two
> overlooked this or not, but it does mean that you're simply looking
> for anything that's 10^N ly in size/distance, where N is any integer.

Yes, in fact my figure of 1 e21 m for Milky Way diameter was a
direct translation from 100,000 light-years, to one SD accuracy.

***-- Jeff, in Minneapolis

Jeff Root · #7 (**permalink**) 13-July-2005, 02:54 AM

Grey,

If your figure for the distance of the Dumbell Nebula is right,
it will certainly be more visually-interesting than the object
I had pencilled in: Deneb.**(Co-incidentally not that far away
in the sky.)**My pre-Hipparcos field guide says the big Dumbell
is 3,500 light-years from us.**Now that you gave me the clue,
I'll track down newer distance figures for it.**My figure for
Deneb is 1,600 light-years-- not particularly close to a whole
order of magnitude, but it has the advantage of being something
almost anyone can go outside and see easily.

Thanks!

***-- Jeff, in Minneapolis

Grey · #8 (**permalink**) 13-July-2005, 03:11 AM

Quote:

Originally Posted by Jeff Root

Now that you gave me the clue,
I'll track down newer distance figures for it.

I got the figure here, and it looks like it's confirmed here, so it's probably accurate. Interestingly, though, there's a link from the SEDS page (to Bill Arnett's photos) that gives the same 3,500 light year figure that you mention.

Jeff Root · #9 (**permalink**) 16-July-2005, 12:35 PM

Any more suggestions?**There are several orders of
magnitude left to go!**Galaxy clusters?**Individual galaxies?

***-- Jeff, in Minneapolis
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