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The Jupiter Mission
Activity 3B: Finding Jupiter's Moons
Objective
To calculate and predict the location of Jupiter's 4 large moons
Ask students how the earth's moon moves. Then ask how a satellite moves.
(Both are in orbit around the earth.) Ask how long it takes for the moon
to circle the earth (27.3 days). Ask how long it takes for the Shuttle
to circle the earth (90 minutes). Assist students in concluding that objects
nearer the earth orbit at a faster speed and with a shorter period.
Explain that Jupiter has four large moons that will be visible to the
KAO infrared detector even in the daytime (though Io may be tough to find!).
However, the tracker telescope, using visible light, may not be able to
see the moons during the day--only Jupiter.
Materials activity 3B bound into a Mission Logbook
Procedure Study the diagrams of Jupiter's moons in orbit around
the planet. Explain that the "squashed" image represents exactly
the same scene as the overhead view. When we observe Jupiter from earth,
we have an edge-on view of the moons. By comparing image (i) and (ii),
students can see how much each moon moves in 16 hours. To figure out where
Jupiter's moons will be at the time of the KAO observations, move each
moon half as far again as it moved between image (i) and image (ii). Mark
the position of each moon with a black circle on image (iii). Then carry
those positions down to the edge-on view.
Ask students to draw Jupiter with the moons correctly shown for the
time of the observation. Use 16:00 hrs Eastern as the baseline, and adapt
the spacing accordingly. Then ask students to estimate the orbital period
for each moon in earth days. (Io: 1.7 days, Europa: 3.6 days, Ganymede:
7.2 days, Callisto: 16.7 days)
Interdisciplinary Connection
All the planets of our solar system also have different speeds in their
orbits around the sun. The table below lists the period for each planet
in terms of earth years. Ask students if the orbital periods change in
the same way for the planets as they do for the moons of Jupiter. For
older students, you can introduce Kepler's Third Law of Planetary Motion.
Mercury |
0.24 earth years |
Venus |
0.61 earth years |
Earth |
1.0 earth year |
Mars |
1.9 earth years |
Jupiter |
11.9 earth years |
Saturn |
29.4 earth years |
Uranus |
83.8 earth years |
Neptune |
163.7 earth years |
Pluto |
248.0 earth years |
KAO Connection
Ask students to describe how to find each of the moons once the telescope
has located Jupiter.
Jewels
Myra Cohn Livingston
Space blazes with jewels,
a shimmering ice
of billions of diamonds
dazzles
the Milky Way:
Jupiter, a giant agate,
Uranus, a ball of jade,
Pluto, a luminescent pearl,
Saturn, a halo of rings,
A slice
of moon, a crescent brooch.
Bright rubies splay
Antares
in this
midnight
masquerade.
From Space Songs, by (Holiday House, New York) (c) 1988 by Myra
Cohn Livingston. Used by permission of Marian Reiner for the author.
When I Heard the Learn'd Astronomer
Walt Whitman (1819-1892)
When I heard the learn'd astronomer,
When the proofs, the figures, were ranged in columns
before
me,
When I was shown the charts and diagrams, to add, divide,
and measure them,
When I sitting heard the astronomer where he lectured
with much applause in the lecture-room,
How soon unaccountable I became tired and sick,
Till rising and gliding out I wander'd off by myself,
In the mystical moist night air, and from time to time,
Look'd up in perfect silence at the stars.
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