Download Rotation and Revolution

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Rotation and Revolution
A planet is a large body that shines by reflected light and travels in a stable path
around a star. The sun is the star of our solar system and controls the motion of all
the planets that travel around it. The planets are illuminated, or lit up, by sunlight.
Some planets may be mistaken as bright stars on a clear night. However, when
carefully observed, planets shine with a steady glow of reflected light, whereas,
stars appear to flicker or twinkle.
A planet has two important motions that occur at the same time:
1. It spins on an axis.
2. It moves in an orbit around a star.
Rotation is the spinning of a planet on its axis. The time it takes a planet to
complete one spin is called its period of rotation. The period of rotation is known
as a day on that planet. The time it takes for a planet to complete one rotation
varies from planet to planet.
As the planet rotates on its axis, half of the planet is bathed in sunlight and half is
not. The side of the planet facing the sun experiences daytime; the other half has
nighttime. On Earth, a period of rotation lasts about 24 hours or one day.
Revolution is the movement of a planet in a path, called an orbit, around a star.
The period of revolution is known as a year on that planet. The time it takes for a
planet to complete one revolution depends on the distance between the planet and
the star. On Earth, a period of revolution lasts 365 days or one year.
Rotation and Revolution
Average
Distance from
sun (millions of
km)
Average orbital
speed
(km/s)
Period of
Revolution
(Earth years)
Mercury
58
47.8
0.24
Venus
108
35
Earth
150
Mars
Period of
Rotation
(Earth days)
Period of
Rotation
(Earth hours)
87.6
59 days
1416
0.62
226.3
243 days
5832
29.8
1
365
1 day
24
228
24.2
1.9
693.5
1.03 days
24.72
Jupiter
778
13.1
12
4380
0.41 days
9.84
Saturn
1427
9.7
29
10585
0.43 days
10.32
Uranus
2871
6.8
84
30660
0.72 days
17.28
Neptune
4497
5.4
165
60225
0.67 days
16.08
Planet or
Object
Period of
Revolution
(Earth days)
[Earth year x 365]
[Earth days x 24]
1. Calculate the “Period of Revolution (Earth Days)” for each object by multiplying the “Period of Revolution (Earth Years)” by 365.
2. Calculate the “Period of Rotation (Earth Hours)” for each object by multiplying the “Period of Rotation (Earth Days)” by 24.
Turn over your paper and complete the questions on the back.
Jupiter
rotation?
19. Which planet spins the fastest on its axis, or has the shortest period of
Neptune
20. Which object has the longest year, or longest period of revolution?
Mercury
21. Which object has the shortest orbit, or shortest period of revolution?
Venus
22. Which object has the longest day, or longest period of rotation?
23. How are the “Average Distances From the Sun” and the “Period of Revolution” related?
The further a planet is from the sun, the longer its period of revolution
More
24. Planets closer to the sun than Earth take a shorter amount of time to revolve
around the sun. Therefore, their years are shorter. Do you have more or fewer birthdays on
planets that are closer to the sun than Earth?
Fewer
25. Planets farther from the sun than Earth take a longer time to revolve around
the sun. Therefore, their years last longer. Do you have more or fewer birthdays on planets that
are farther from the sun than Earth?
Between 44 – 48 26. A year on Mercury is .25 of a year on Earth or ¼ of Earth’s year. It
revolves around the sun 4 times in one Earth year. How old would you be on Mercury?
(Careful! Check your answer to #24 before you write down your answer here.)
Between 5 – 7 27. A year on Mars is almost twice as long as a year on Earth. Or, Earth takes
half the time Mars does to revolve around the sun. About how old would you be in Mars years?
(Careful! Check your answer to #25 before you write down your answer here.)