A View from the Back of the Envelope top

Petameters in your hands
1015 meters per mm (Magnification of ×10-18)
If a light-year is 1 cm...
Scaling the universe to your desktop
How Big Are Things?
Length Area Volume Speed
10 [ -6 | -3 | 0 | 3 | 6 | 9 | 12 | 15 | 18 ]
1018 meters per meter

1 Pm

10 Pm

100 Pm

1000 Pm
1015 m
0.3 Pm
316 Tm
3 Pm
3162 Tm
1016 m
32 Pm

3.34 lt·yr
1017 m
316 Pm
0.3 Em
33.4 lt·yr
1018 m
3162 Pm
3 Em
334 lt·yr

a light year (ly)
9.461 Pm

a parsec (pc)
30.86 Pm

to Sirius
81 Pm

Ross 248
101 Pm

Some systems:
a Centauri41 Pm
Barnard's Star57 Pm
Wolf 35971 Pm
Procyon108 Pm
Altair156 Pm

8 solar systems
are < 100 Pm distant

distance to Local Bubble wall
~~2500 to ~~3000 Pm

"complete dust depletion"
bubble diameter
~~2000 Pm

[ Size of the 1000 Pm box is _rough_. ]

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

~10 Pm tall clouds (false color)
1/2 lt·Gs (ticks every 1/10 light-gigasecond (lt·109s))
0 1/10 2/10 3/10 1/2 lt·Gs
A sketch of the local stars.
Star size is very false (actually... star is ~atom and solar system is ~blood cell).

[ Image courtesy of Winchell Chung of 3-D StarMaps. Thanks! ]
The third coordinate is depth. All are in parsecs.
Basically, BD is ~5cm towards you, Sun/Barnard's/Wolf are ~on the screen, and the others are ~3cm behind it.
There are some stereo pairs here, which might make it easier, though the orientation and names are different :(.


3-D StarMaps including these.
3-D Mapping of the Local Interstellar Medium

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

  starmap: Figure out orientation.
    Ideally would have galactic orientation (this is celestial?),
    some depth cue (perhaps a galactic plane grid),
    cross-hairs rather than icons (to avoid false size cuing),
    Pm rather than pc distances.
  sketch of local stars, ly and pc.
  local bubble
    clarify dimensions, describe egg shape
    describe dust and gas densities
  more about local neighborhood
  Limit of reliable distance info (Hipparcos?) 100 pc?  Reliable means what?
  landmarks: ltyr=10^16, pc=3ltyr, 
  "Some ?? systems total." in ^17 and ^18 frames.
  Make size of local bubble image and box a bit less sloppy.
  Quote from pillar cloud caption, regarding erosion process.  Neat.
  Cloud pillar slightly (50%?!) too big I think...!! Drat.
  Starmap was contributed by Winchell Chung and resized slightly.
  Sketch of local bubble derived from The 120 pc Map: the Local Bubble
   in 3-D Mapping of [LIM].
    The sizes of this ~3000 Pm cropped image, and of the ~1000 Pm red box,
    are very rough, having been done very quick and sloppy.
  Local Bubble from 3-D Mapping of [LIM] and [Paresce]
  Complete depletion of dust within 35 pc,
    with signature beginning mostly 70-100 pc [Leroy]
  Pillar clouds from here (Hubble).
    Size of image is not quite correct - tallest pillar is about a ly long.
    I am uneasy about using false-color images - one's grip on reality is
    weak enough...
  2003-Feb-03   Repaired links - 6 fixed.
  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 pillar clouds image.
  1998.Apr.18   Added starmap.
  1998.Apr.17   Added local bubble sketch.
  1998.Apr.15   Created.