Scale SOLAR SYSTEM copyright David Carpenter 2001
The 80 inch Earth
is a great model for visualizing Earth. But it is way too big for
visualizing the solar system. We are going to use a model over
1000 times smaller, and
even still, we will need to take long walks to see all of the solar
system.
The solar system model is based on a basketball-sized
Sun. If we place our
basketball-sized Sun on home plate of a regulation baseball field,
we can place a small
shotgun-BB 90 feet away on first base. This will represent Earth,
at the proper distance
and the proper scale.
The moon can also be placed in this model.
The moon will be a grain of salt,
orbiting the shotgun-BB Earth, 3 inches away from Earth.
We can complete the inner solar system by adding
only two more objects. Since
Venus is only slightly smaller than Earth, another BB will work fine.
Place it in orbit
about 65 feet from the basketball at home plate. Mercury is tiny,
not much larger than our
moon, so another grain of salt can be placed in orbit around the basketball
at a distance of
35 feet. And that's it, the entire inner solar system.
The total diameter is 180 feet, most of
the space is empty space with only one basketball, two shotgun BB's
and two grains of
salt.
Let's put this into perspective. Imagine you
are sitting in a high school football
stadium. Imagine that there is a big, hollow, cellophane ball
in the center of the field, 180
feet in diameter. That's nearly 2/3 of the length of the field
and 30 feet wider. If you are
standing on the sidelines at the 50 yard line, the ball will extend
15 feet past you, 90 feet
over your head. Looking inside, at the center, is a basketball.
In all the rest of the
empty space inside the cellophane ball, there are only two BB's and
two grains of salt.
The rest is empty space.
That's how empty space is. And that's how empty
it is in the inner solar system,
where things are close together. No wonder solar system pictures
in books are never
accurate. If you draw the orbits to scale, the planets are too
small to see. If you draw the
planets to scale, the orbits won't fit on the page (they probably won't
even fit in the same
county!).
Of course, we are not done. There are planets
beyond Earth as well. Mars can be
placed 137 feet from the basketball. Too small to use a BB, too
big for a grain of salt, a
fleck of pepper will have to suffice for our model Mars.
Next is the asteroid belt. But the asteroids
are too small to see at this scale. We'll
have to leave them out.
Then comes the big guy, Jupiter. A full inch
in diameter, this largest of the planets
will need a "boulder" size marble. Four grains of salt
whirling a couple inches around it
will represent its largest moons. Jupiter will orbit the basketball
Sun at a distance of 467
feet. That's farther than a major league homerun away.
[It's also slightly farther than the
straight-line distance between our physics room and the
school cafeteria.]
Even with Earth modeled the size of a shotgun-BB,
our model solar system is
getting too large. Jupiter is just the first of the gas giants.
Saturn is nearly as large (7/8
inch), and can be modeled with another boulder marble. Its orbit
will be 858 feet from the
basketball Sun. Uranus is an ordinary-sized marble 1/3 mile (1720
ft.) away, and Neptune
is another marble 1/2 mile (2700 ft.) away. Pluto is about the
same distance, and too small
to model. Saturn and Neptune need at least one salt grain orbiting
around them.
Well that's it. A model of our solar system.
The entire thing (neglecting comets in
the Oort cloud and Kuiper belt) fits in a sphere of space one mile
in diameter. Imagine
that, a hollow cellophane sphere 1 mile in diameter. That's the
distance from Hayes High
School, all the way to the end of Euclid Avenue at Central, then jogging
down Elizabeth
Street to William Street (right in front of the Ohio Wesleyan Student
Observatory!).
Imagine a sphere that large. Imagine driving into Delaware and
seeing that sphere rising
above the city, five times as high as the Empire State Building.
In that incredible volume
(8 x 1010 ft3) there is only one basketball,
two boulder marbles, two regular marbles, two
shotgun-BB's, one fleck of pepper, and a few grains of salt.
There is one amazing amount
of empty space.
Wow!
So how far apart are the solar systems? How far away is
the nearest
basketball/star? At this scale, Alpha Centauri is 4600 miles
away! You have to drive to
the far end of South America to drop off the next basketball!
That's how far away stars
are at the same scale! And that's in a spiral arm of a galaxy
where stars are relatively close
together. There is nothing between these basketballs except for
empty space. Continuing
at this scale, where Earth is the size of a BB, our galaxy of billions
and billions
of basketballs would fill the entire real Earth's orbit around the
Sun! And there are
countless galaxies in the universe.
Space is BIG,...real BIG, and real empty.
copyright David Carpenter 2001
