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World
Builders™
Session
One -- Astronomy
Information about
Planets and Moons
In our Solar System
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This
information will help you to pick sizes and densities for your world.
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Here is some information about the planets
and moons in our own solar system. I have gathered these
numbers
from many sites on the web, the majority of them being NASA sites.
Look at these tables to get some ideas of
planet and moon sizes. Then you can decide what you want your
planet to be like.
Hints:
Work out your year length
first.
Check
Kepler's
Third Law to see how
to do the math.
Check
out Circle Talk to help you
with getting your planets to the right size.
Use the Earth = 1 measurements.
You can pick just about any day length that
you like. To be on the safe side, make it more than about 8 hours.
If the day length is too short, the planet might
come apart. This
would happen if the speed
of the planet at the
equator is faster than the
escape velocity from that
world.
Go to Calculating
Your Planet's Gravity when you have decided on either
the radius (blue) or the
Density
in grams/cm^3 (in 0range column) of your planet.
You can also Calculate
Your Moon's Orbit. |
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Our
Solar System -- Planets and the Sun
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Year
Length in Earth Years |
Day Length
in
Earth Days |
Distance
from Sun in AUs |
Radius
in Kilo- meters |
Radius
When Radius of Earth = 1 |
Mass
When Mass of Earth =1 |
Density
when Density of Earth
=1 |
Den-
sity
in
grams
cm^3 |
Gravity
when Gravity of Earth = 1 |
Escape Velocity in Kilo- meters/
Second |
Mean
Kelvin Temp-
erature
(Minimum- Maximum) |
Atmos-
phere |
Moons |
| Sun |
|
. |
0 |
700,000 |
109 |
332800 |
.25 |
1.41 |
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6000 |
- |
- |
| Mercury |
.2
(88 days) |
176 days |
.39 |
2,440 |
.38 |
.05 |
.98 |
5.43 |
.4 |
4.3 |
452
(100 - 700) |
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0 |
| Venus |
.6
(225 days) |
117 days
one revol-
ution 243 days |
.72 |
6,052 |
.95 |
.89 |
.95 |
5.25 |
.9 |
10.4 |
726 |
Carbon
Dioxide 96%
Density
is 100 times
Earth |
0 |
| Earth |
1 |
24. hrs |
1 |
6,378 |
1 |
1 |
1 |
5.52 |
1 |
11.2 |
281
(260 - 310) |
Nitrogen 77%
Oxygen 21%
Other 2% |
1 |
| Mars |
1.9 |
24.6 hrs |
1.5 |
3,397 |
.53 |
.11 |
.71 |
3.95 |
.4 |
5.0 |
(150
- 310) |
Thin Carbon Dioxide
atmos_
phere |
2 |
| Jupiter |
12 |
10 hrs |
5.2 |
71,492 |
11 |
318 |
.24 |
1.33 |
2.5 |
59.5 |
120 at
cloud
tops |
|
16 or
more |
| Saturn |
29.5 |
10 hrs |
9.5 |
60,268 |
9.5 |
95 |
.125 |
.69 |
1 |
35.6 |
88 |
|
19 or
more |
| Uranus |
84 |
16.5 hrs |
19.2 |
25,559 |
4 |
15 |
.23 |
1.29 |
.9 |
21.30 |
59 |
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| Neptune |
165 |
16 hrs |
30.1 |
24,766 |
4 |
17 |
.3 |
1.64 |
1.1 |
23.3 |
48 |
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8 or
more |
| Pluto |
248.6 |
6.4 hrs |
39.5 |
1,137 |
.18 |
.002 |
.37 |
2.03 |
.5
? |
1.1 |
37 |
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Here is some information on Moons. You can
see that they come in many sizes, so you have a lot of choice.
Be sure to locate your moons
outside The
Roche Limit!
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Information
about Some Moons in 0ur Solar System |
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Orbits around |
Period for One Orbit Around the
Planet in Earth
Days |
Diameter
in km
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Radius When
Radius of Earth = 1 |
Mass when Mass of Moon = 1 |
Mass in Kg |
Density
in grams
cm^3 |
Escape Velocity in Kilometers/
Second |
Average Distance from its Planet in Km |
| moon |
earth |
27.3 |
3476 |
.27 |
1 |
7.35*10^25 |
3.34 |
2.4 |
384,400 |
| Deimos |
Mars |
1.23 |
12.6 |
.001 |
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1.8
*10^15 |
1.7 |
|
23,460 |
| Phobos |
Mars |
.3 |
22.2 |
.002 |
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1.08*10^16 |
2.0 |
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9,380 |
| Callisto |
Jupiter |
16.7 |
4800 |
.38 |
1.5 |
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1.8 |
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1,883,000 |
| Ganymede |
Jupiter |
7.1 |
5262 |
.4 |
2 |
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1.93 |
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1,070,000 |
| Europa |
Jupiter |
3.5 |
3138 |
.25 |
.7 |
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3.04 |
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670,900 |
| Io |
Jupiter |
1.8 |
3630 |
.28 |
1.2 |
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3.55 |
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422,000 |
| Titan |
Saturn |
15.9 |
5150 |
.4 |
1.9 |
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1.88 |
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1,221,830 |
| Dione |
Saturn |
2.7 |
1120 |
.15 |
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1.05*10^24 |
1.4 |
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377,400 |
| Tethys |
Saturn |
1.9 |
1060 |
.08 |
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6.26*10^23 |
1 |
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295,000 |
| Rhea |
Saturn |
4.5 |
1530 |
.12 |
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2.28*10^24 |
1.3 |
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527,040 |
| Mimas |
Saturn |
.9 |
392 |
.03 |
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3.7*10^22 |
1.2 |
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185,520 |
| Iapetus |
Saturn |
79 |
1460 |
.11 |
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1.93*10^24 |
1.1 |
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3,561,300 |
©
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 eviau@earthlink.net.
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