MODEL SOLAR SYSTEM TRAIL
Welcome to the Otter Creek
Observatory Model Solar System trail.
This short trail (approximately 350 yards or 1/5 mile each way)
illustrates the true size and scale of the solar system. The relative sizes of the planets and Sun,
and the distances between them, are all properly scaled. As you walk this trail you will gain an
appreciation for how vast -- and how empty -- our Solar System truly is.
The
trail starts at the front entrance to the
Pluto
is, on average, the most distant planet from the Sun. Pluto has a very “eccentric” orbit that
occasionally takes it inside the orbit of
In
the real Solar System, Pluto is roughly 4 billion miles away from the Sun, and
measures about 1400 miles in diameter.
But what is a billion miles anyway? Nothing on Earth is a billion miles across,
or a billion miles tall. In fact, even
whole continents on Earth are only thousands of miles across. So what is 4 billion miles?
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Click
here for more on Pluto. |
Photo of
Pluto from the Hubble Space Telescope |
For
one thing, 4 billion miles is roughly 40 times the distance from the Earth to
the Sun. Astronomers call the distance
from Earth to the Sun an Astronomical Unit (or AU). Pluto is 40 AU from the Sun. However, unless you are an astronomer that probably
does not tell you much.
Think
of it this way -- if you drive on the interstate you can travel 1000 miles
(roughly the distance between
Distances
in space are far greater. For example,
were there an interstate highway from Earth to the Moon it would take just
under eight months of hard driving (eighteen hours a day, seven days a
week -- no days off) to make the trip.
By the time you got there your car would have about 250,000 miles on the
odometer.
But
that’s nothing compared to driving from Pluto to the Sun. Driving eighteen hours a day, seven days a
week, going 70 mph with stops for gas, eats, toilet, it would take you more
than ten thousand years to drive from Pluto to the Sun -- longer than
all of recorded human history! That’s
how far 4 billion miles is!
On the other hand, it would not be hard to drive
around Pluto. At 1400 miles in diameter
Pluto is about 17% of the diameter of the Earth. If there were an interstate around Pluto you
could drive completely around the planet in a little over 4 days of hard
driving.
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The
size of Click
here for more on |
Enough
about Pluto. Follow the sidewalk past
Pluto and turn left around the corner of the
Continue
down the Otter Creek Trail until you reach the main road (
You
will come upon the plaque for Uranus.
Uranus is similar in size to
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The size of Uranus in the Model Solar System: Click
here for more on Uranus. |
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Hey,
the trail is only 350 yards long, and you only have 170 yards to go. You are more than half way through and you
are only to Uranus! Is that right? Yes it is.
The outer planets in the Solar System are very far-flung.
Keep
following the gravel road. After a few
dozen yards you will come upon Saturn’s plaque. Saturn is a big planet. At over nine times Earth’s diameter it would
take about 235 days of hard interstate driving to circumnavigate it. The mark for Saturn on the plaque is over a
quarter of an inch in diameter. Saturn’s
famous ring system is also represented on the plaque as a lightly abraded
region. Saturn is 9.5 AU from the Sun --
a mere 2,400 years’ drive.
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The size of Saturn in the Model Solar
System Click
here for more on Saturn. |
The
Saturn plaque lies about 85 yards from the Sun at the end of the trail. By this point you can probably see the end of
the trail (the observatory). It’s the
small white building up ahead of you.
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The size of Jupiter in the Model Solar System. Click
here for more on Jupiter.
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And
speaking of big planets, up ahead lies the king of them all -- Jupiter. Jupiter is over ten times the diameter of
Earth. Driving all the way around
Jupiter would take 280 days of hard driving.
The Jupiter plaque is 46 yards from the end of the trail. This represents a distance of 5.2 AU, or
1,300 years worth of driving.
After
Jupiter, head towards the observatory.
You will see the plaques for the inner Solar System (Mars, Earth,
Venus, and Mercury). The
inner Solar System is comparably compact compared to the part of the Solar
System you just passed through. These
planets are all just a few steps from one another.
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Mars:
The
mark on the Mars plaque is hard to see at about 15 thousandths of an inch in
diameter. |
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Earth:
The
mark on the Earth plaque is about 30 thousandths of an inch in diameter. |
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The size of Earth in the
Model Solar System. Click
here for more on Earth. |
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Venus:
The
mark on the Venus plaque is also about 30 thousandths of an inch in diameter. |
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Mercury:
The
mark on the Mercury plaque is the hardest one to see after the one for
Pluto. It is about 10 thousandths of
an inch in diameter. |
The size of Mercury in
the Model Solar System. Click
here for more on Mercury.
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And then, on the
door of the observatory you will find The Sun. On the plaque the Sun measures a full 3
inches in diameter, reflecting the fact that the Sun is about 110 times the
diameter of the Earth. Were it possible
to go on a driving trip around the Sun, it would take you over seven years
to do it! The Sun dwarfs all the
planets -- even Jupiter.
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The
size of The Sun in the Model Solar System.
Click
here for more on The Sun.
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As
you walk back from the Sun through the Solar System, keep this in mind:
Light travels at a speed of 186,000 miles
per second. That translates into one AU in 8.3 minutes. So, to travel at the speed of light, start at
the Sun, and walk so slow that it takes you 8.3 minutes to reach the Earth, 43
minutes to reach Jupiter, 2.7 hours to reach Uranus, and 5.5 hours to
get back to Pluto at the Nature Center!
Of course you won’t do that, so think about the fact that as you walk
back you are flying through the Solar System, seeing the exact same view as you
would in the Star Ship Enterprise traveling at a fictional “Warp Speed” through
the Solar System -- many, many times faster than the speed of light. Light may be the fastest thing in nature, but
for us it is pretty slow.
What about the
stars? How far away are they in this
model? Well, imagine we draw a circle,
centered on the Sun, a little outside
the orbit of Pluto. The Sun and all of
the planets are inside this circle.
Let’s call this our model’s Realm of the Planets. It contains all the largest known bodies in
the Solar System.
Now let’s step back
from the model a bit. We see the Realm
of the Planets for our model, and the trail you are walking, along with the
rest of
Now
we have stepped back far enough to see parts of Meade and Hardin counties, as
well as nearby towns including
Now
we can see most of the continental
So
if the Sun is a circle 3 inches in diameter located on the door of the
observatory, then Pluto is located by the
If
you traveled through our model at the speed of light, you would leave the Sun and
take 8.3 minutes to get to Earth, 43 minutes to reach Jupiter, 2.7 hours to
reach Uranus, 5.5 hours to get back to Pluto at the
The
scale of this model Solar System is 16.89 million kilometers to the yard, which
was chosen to allow Pluto to be at the
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