of the sidereal periods of the planets are proportional to the cubes of
their semimajor axes.
language for a number multiplied by itself:
Example: 6 x 6 = 36
sidereal periods of the planets
we would call this the planet's year
is a journey of one full orbit around the sun.
mathematically related to
language for a number multiplied by itself
multiplied by itself again.
6 x 6 x 6 = 216
We need a diagram here:
First Law) that the planets move in elliptical
is an ellipse.
major axis of an ellipse is a line drawn
through both foci.
you can see the major axis drawn in red.
we need to find the semimajor axis.
means half, so let's cut the major axis in half.
we see the semimajor axis in red.
We can use the
mean distance of the planet
from its sun as the number for the semimajor axis.
The mean distance
of the earth from the sun is 93,000,000 miles.
This is called one astronomical unit, or AU
This law uses the
astronomical unit as the distance number for calculating the length of
Now you are ready
to calculate the orbital information for your planet,
the Life Zone (Habitability Zone) for Your Planet.
the Year Length When You Know Your Planet's Distance from the Sun
Your Planet's Distance from the Sun When You Know the
© 1998, 2003. Elizabeth Anne Viau.
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