Just the planets (1)
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School
St. Petersburg College *
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Course
1000C
Subject
Astronomy
Date
Dec 6, 2023
Type
docx
Pages
3
Uploaded by jillianstar
The Planets
Name __Jillian Desmarais___________________
Planet
AU
from
the Sun
Period of
revolution
Period of
rotation
Diameter
(mi)
Mass
relative to
Earth
Density
Number
of
moons
Mercury
0.4
88 D
59 D
3015.06
0.056
5.4
0
Venus
0.7
224.7 D
244 D*
7526.18
0.82
5.2
0
Earth
1
365.25 D
1 D
7919.88
1
5.5
1
Mars
1.5
687 D
1.02 D
4216
0.108
3.9
2
Jupiter
5
11.86 Y
0.4097 D
88700.3
317.87
1.3
79
Saturn
10
29.46 Y
0.426 D
75000.16
95.14
0.7
82
Uranus
20
84 Y
0.718 D
28999.88
15.56
1.2
27
Neptune
30
165 Y
0.669 D
28900.06
17.21
1.7
14
D is Earth days
Y is Earth years
*Retrograde – Venus is spinning clockwise not counterclockwise.
Density is mass per unit of volume water has a density of exactly 1, ie one gram per cubic
centimeter. Look at the densities of the Jovian versus the terrestrial planets.
1)
What is the average density of the Jovian planets?
1.2
2)
What is the average density of the terrestrial planets?
5
3)
Why are they so different?
Because of what they are made up of. The terrestrial planets are made of rocks and
the jovian planets are made of gas.
Remember that period of rotation is how long it takes a planet to spin. It can also be
thought of as how long a day is. The unit “D” for period of rotation is Earth Days.
4)
How long is a day on Mercury?
59D
5)
How long is a day on Neptune?
0.669D
6)
Does distance from the Sun have anything to do with the period of rotation?
Yes
7)
Do jovian planets have longer or shorter days than terrestrial planets?
They have longer days because of how far away from the sun they and and how
much rotation they have to complete one full rotation around the sun.
8)
So are they spinning faster or slower than terrestrial planets?
They are spinning slower
Revolution is how long it takes a planet to go around the sun. This is a year on that planet.
9)
How long is a year on Mercury?
88D
10)
How long is a year on Neptune?
165D
11)
Is the period of revolution related to distance from the sun? If so How?
Yes, because the further from the sun a planet is the longer it has to go around in
order to make a full rotation which then goes into making a full revolution around
the sun.
Remember that Kepler’s third law relates how far a planet is from the sun to its orbital
period.
P
2
=D
3
where P is the period and D is the distance to the sun in AUs.
So if a planet is 2 AUs from the sun;
P
2
= D
3
P
2
= 2
3
P
2
= 8
P =
√
❑
P= 2.8 Earth Years
So it takes the planet 2.8 Earth years to go around the Sun
12)
What is the orbital period of a planet that sits 3 AUs from the sun?
5.1 AUs
13)
What is the orbital period of a planet that sits 7 AUs from the sun?
18.5 AUs
We can use the period of rotation and revolution to figure out how many of a planets days
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