Last Update:  5-1-2002

Encyclopedia-Style Reference
Cosmiverse Reference Library 

Questions/Answers about Science, Astronomy and Physics
All Experts: Ask the Astronomer
Ask the Space Scientist
Astroplace: Ask an Astronomer
PhysLink: Physics & Astronomy: Ask the Experts  
Scientific American: Ask the Experts

Mathematics, Formulas, Constants, Calculators, Distances
Astronomic Constants   James Jacobs
Astronomical Distances   Douglas Hamilton   spacecraft speed and time/distance to object
Astronomy Formulas   James Jacobs
Astro and Physics Calculators On-line   Martindale
Constants & Equations  Jonathon Stott    science, math, astronomy
Cosmographic Values   James Jacobs
Math Tables   Dave Manura    algebra, geometry, integrals & more
Mathematical Constants   Steven Finch
Mathematical Concepts On-line   interactive virtual animations
Powers of Ten   Molecular Expressions
Scientific Notation Exercises   Douglas Hamilton   learn scientific notation  
Solar System Calculators   Douglas Hamilton   planetary calculator, satellite calculator
Unit Conversion On-line    PhysLink
Unit Conversion On-line   Science Made Simple

Miscellaneous
Nick Strobel's Astronomy Notes    an EXCELLENT website! 
 > Introduction to Astronomy  size, time, scientific models, astrology
 > Astronomy without a Telescope  celestial coordinates, time, seasons, planetary motions
 > Newton's Law of Gravity
 > Einsteins Theory of Relativity
 > Electromagnetic Radiation (Light)
 > Telescopes  types and operation
 > Planetary Science   solar system distances, masses, sizes, interiors, atmospheres
 > Solar System Fluff  asteroids, meteorites, comets, solar system references
 > Stellar Properties  everything about stars
 > Our Sun & Stellar Structure  
 > Lives & Deaths of Stars   
 > Interstellar Medium and the Milky Way  
 > Other Galaxies and Active Galaxies  

Build a Solar System   Exploratorium     virtual scale model; learn celestial distances
Eyesight: Sighting the First Sense - Seeing Is Believing   Think Quest   eyesight
Greek Alphabet    PhysLink
Handbook of Astronomy & Astrophysics   Martin V. Zombeck
Matter-Antimatter    power for voyages to the stars
Periodic Table of Elements:
  > Chemicool Periodic Table
  > ExploreZone Periodic Tables
  > WebElements Scholar Edition
  > Michael Dayah's Periodic Tables
Solar System Collisions   Douglas Hamilton   you choose the object, speed and target
Windchill & Humidex Calculator    PhysLink
How to use a Compass

Distance Scale Model of the Solar System  
source: Lowell Observatory

In discussing distances in space, it is often difficult for students to grasp the true extent of the numbers used.  Even if we restrict the discussion to the solar system, we're still dealing with units in the millions and billions.

The best way for students to understand such great numbers is to create a visual demonstration, in this case a model of the solar system that is scaled down so that the distance from the sun to the outermost planet, Pluto, is 300 feet (100 yards), the length of a football field.  Thus, the sun would be at one goal line and Pluto at the other.  Measurements are in English units, since this is the system in which football fields are measured.

On this scale, 1 foot equals 12.22 million miles.  The second column lists the scale model distance from the sun to each planet.  (Note that these numbers are rounded off to the nearest foot.  If you want the exact number for each, simply divide the appropriate number in the third column, which lists approximate distances to the planets, by 12.22.)

     Sun  0 feet (Sun's goal line)     ---
     Mercury 3 feet (1 yard line)     36.0 million miles
     Venus  6 feet (2 yard line)     67.2 million miles
     Earth  8 feet (between the 2 and 3 yard lines)  92.9 million miles
     Mars  12 feet (4 yard line)     141.5 million miles
     Jupiter  40 feet (between the 13 and 14 yard lines)  483.3 million miles
     Saturn  73 feet (between the 24 and 25 yard lines)  886.2 million miles
     Uranus  146 feet (between the 48 and 49 yard lines)  1783.1 million miles
     Neptune 229 feet (between Pluto's 23 and 24 yard lines) 2794.0 million miles
     Pluto  300 feet (Pluto's goal line)    3666.0 million miles

To make the model, start at one end zone and measure off the distance for each planet, putting a marker down for the position of each planet.  When you are done, you have a very easy-to-understand model of the solar system.  Especially noticeable will be the distances to the outer planets.  While the
Earth is relatively very close to the sun, for example, Pluto is all the way at the other end of the field.

For more fun, think about traveling outside of the solar system.  The next closest star to the sun, Proxima Centauri, is 4.23 light years away, or about 25 trillion miles.  On the scale model, this would come out to be about 387 miles!