you planning to have life on this planet? If so --
the page on the Life Zone to find out why you
need to put your planet in it.
these directions to find the best distance between your planet and your
distance will be measured in AUs.
An AU is a
distance measure, like a mile or a kilometer. However, space is so immense that
we need to use a much longer measure of distance. An AU is the distance from
the center of our earth to the center of the sun.This distance is about 93 million
If your sun
is brighter and hotter, you need to put your planet farther away to get earth-like
intensity of heat and light.
If your star
is cool and dim, you need to put your world closer to your star than our earth
is to the sun.
to the Star
you chosen your star type? You need a star that has a life span long enough
for life to develop.
that the star that you have chosen is a K4 star.
part of the star tables that you have chosen might look like this:
K Class Stars:
Small, Dim, Red Stars: Could Perhaps Support Life On Inner Planets
in degrees Kelvin
(Mass of our sun = 1)
(Radius of Sun=1)
in billions of years
The yellow row is the one that we have chosen for this example. You can see
K4 in the green column.
Look at the row carefully. Notice that the mass and the radius of this star
are less than the mass and radius of our sun.
Would you expect this star to be hotter or cooler than our sun?
Check the temperature. The surface temperature of the star is about 4590 degrees
Our sun's surface temperature is 5860 degrees Kelvin.
So the K4 star is smaller and cooler than Sol (our sun)
What will happen if you put your world one AU from the center of this planet?
Will it be warm enough to have liquid water?
Well, probably not. Turn your attention to the blue column called
in AUs. This column tells you where to put your planet so that it will
get the same amount of solar radiation as our earth. This is in the life zone.
Look for the number in the
blue column that is the Terrestrial Equivalent Orbit in
See, here it is in the blue
column. The number is 0.43 This planet
will be closer to its star than earth is to Sol. This is the number that
you will use when computing the year length of your world.
Write down the number of
the Terrestrial Equivalent Orbit in AUs for your planet and
go on to
the Year Length When You Know Your Planet's Distance from the Sun
Your Planet's Distance from the Sun When You Know the Year
1998, 2003. Elizabeth Anne Viau. All rights reserved. This material may be used
by individuals for instructional purposes but not sold. Please inform the author
if you use it at email@example.com.