A View from the Back of the Envelope top

Megameters in your hands
106 meters per mm (Magnification of ×10-9)
Scaling the universe to your desktop
How Big Are Things?
Length Area Volume Speed
10 [ -6 | -3 | 0 | 3 | 6 | 9 | 12 | 15 | 18 ]
If the Sun is a big beachball... 109 meters per meter

1 Mm
10 Mm
100 Mm
1000 Mm
106 m
0.3 Mm
316 km 		3 Mm
3162 km
107 m
32 Mm
108 m
316 Mm
0.3 Gm
109 m
3162 Mm
3 Gm

Earth
13 Mm
(a blue & white marble!)

Moon
3.5 Mm

Jupiter
143  Mm

lt·s (light-second)
300 Mm

Sun
1390  Mm

Earth-moon distance
384 Mm
(thus orbit diameter is 769 Mm)


another with more stars

1 Mm per mm
Actual size (though rough, as screen resolution varies).

.

1 light-second seems 0.3 m (1 foot)

1/2 lt·s (ticks every 1/10 lt·s)
0 1/10 2/10 3/10 1/2 lt·s

Links

A nice picture of Io in front of Jupiter from here and here. Io is 3.6 Mm, and only about 210 Mm from Jupiter.
Jupiter's other large moons, Europa, Ganymede amd Callisto, are similarly sized at 3.1, 5.3, and 4.8 Mm.
The relative size of Earth, Jupiter, Sun (1 : 10 : 100)

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu> 

Doables:
 Move your finger at light speed...
 Sun color wrong.
Other meta info on zero magnification page. 
Notes:
 Sun image from Today's Space Weather.  Size from Sun[link broken].
 Jupiter image and size from Jupiter[link broken].  Image is allegedly true color from Hubble.
 Star comparison sketches from How Big is That Star?

History:
 2003-Feb-03   Repaired links - 5 fixed, 2 flagged.
 2001.Apr.20   Added link to `How Big Are Things?'.
 1998.Jun.17   Corrected error with magnitude boundaries (3.333->3.162).
 1998.May.20   Added link to Jupiter & Io picture.
 1998.May.20   Added star size comparison sketches.
 1997.Oct.21   Moved `The relative size...' link from Doables into page.
 1997.Sep.12   Added moon.
 1997.Sep.04   Hacked in a quick lt·s scale.  Eh.
 1997.Aug.28   Added sun and jupiter images.
 1997.Aug.25   Created.