Download HO-04 5a Astro Unit Content

Content for the LSD 5a “Astronomy” Science Unit
Students will be able to describe several behaviors, features, or characteristics that the earth, moon,
and sun share in common, as well as several behaviors, features, or characteristics that make them
different (in other words, “compare and contrast"). The focus for grades K-4 according to the MCF
(2000) benchmarks is on easily observable characteristics (or what might best be thought of as
“naked-eye” observations). These behaviors, features, and characteristics include:
Earth &
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Moon & Sun
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Earth &
Moon
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Earth & Sun
Moon & Sun
Earth
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Handout #4
shape: sphere
location: all are in space and are members of our solar system (which
also includes eight other planets, many of which have one or moons); the sun is
at the center of this system
motion: each spins on its axis (or rotates), although the rates of rotation
are very different
motion: each is moving through space (e.g., the moon orbits or revolves
around the earth, the moon and earth together orbit the sun, and the sun -- along
with all its planets and their moons -- is revolving around the center of our galaxy)
all three have gravity (which pulls objects toward their centers), although
the amount of gravity is very different for each (with the amount being a function
of their size and mass); for example, your weight on the moon would be about
one-sixth that of your weight on the earth
composition: solid, rocky; (earth has a molten core, liquid oceans
covering roughly two-thirds of its surface, and ice at each of its poles)
share some common kinds of surface features, e.g., mountains, plains,
craters
is visible (in space) by reflecting (or bouncing) some of the light that
came from the sun back into space; in this way the earth can be seen from the
moon and the moon can be seen from earth [NOTE that “reflecting” light is not
part of the K-4 benchmarks. It is found in the middle school in benchmarks
IV.4.m.3, IV.4.m.4, and V.4.m.3. Nonetheless, it is probably reasonable (and
necessary) to bring this up in this 5th-grade context in order to clarify that unlike
the sun, the earth and the moon are not “light sources.”]
each has an atmosphere, although the nature/composition of each is very
different
visible in the sky during daytime; (by definition, when the sun is above the
horizon it is daytime; the moon, like the sun, is visible roughly half of each day, but
the moon is visible sometimes during daytime and sometimes during nighttime,
depending where it is in its orbit around the earth)
appear to move from east to west across the sky
planet (a satellite of the sun)
size: the earth’s diameter (12,753 km) is about 4 (3.67) times larger than
the moon’s diameter (3,474 km); the earth’s diameter is much, much smaller than
the sun’s diameter (1,382,000 km)
motion: goes (or revolves) around or orbits the sun, takes one year to
complete one orbit (revolution)
motion: spins (or rotates on its axis); one rotation is called one day (24
hours)
temperature: average surface temperature ranges from -89ºC to +58ºC
sustains life
unique surface features include bodies of liquid water of varying sizes
(e.g., oceans, lakes, rivers)
5a Astronomy Unit Content
2001.09.28 [RTSmith]
Revised 2002.09.09
Moon
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Sun
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Other
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Handout #4
moon (a satellite of earth)
visible in the sky roughly half of each 24-hour day, sometimes during
daytime and sometimes during nighttime, depending where it is in its orbit
around the earth
no atmosphere; no life; no liquid water on the surface
size: the moon’s diameter (3,474 km) is smaller than the earth’s
diameter (12,753 km); the moon's diameter is much, much smaller than the sun’s
diameter (1,382,000 km)
distance: the moon is much closer to the earth than is the sun (the
average distance from the earth to the moon is about 384,467 km)
motion: goes (or revolves) around or orbits the earth, takes about one
month to complete one orbit (revolution)
motion: one rotation takes about one month; since the time it takes the
moon to rotate and revolve are essentially equal, an observable consequence is
that the same portion of the moon always faces toward the earth
temperature: average surface temperature ranges from -173ºC to
+100ºC
star
is at the center of our solar system
size: largest of the 3 (by two orders of magnitude; in fact, the sun is by far
the largest member of our solar system); the sun’s diameter (1,382,000 km) is
more than 100 (108.3) times larger than the earth’s diameter (12,753 km); the
sun’s diameter (1,382,000 km) is almost 400 (397.8) times larger than the moon’s
diameter (3,474 km)
distance: the sun is much farther away from the earth than is the moon
(the average distance from the earth to the sun is slightly less than 150,000,000
km); the sun-earth distance is about 400 (390) times the earth-moon distance
the only member of our solar that continually emits light and heat (the
exceptions being things like meteors as they burn up on entry to the earth’s
atmosphere) [? The light we see coming from a comet's dust tail is reflected
sunlight, but what about the ion tail? Is it also visible simply by reflected sunlight
or by some kind of emitted glow caused by ionization (or some other process) of
its tail?]
composition: very hot ionized gases (i.e., plasma)
temperature: the surface temperature is about 5,500ºC; the interior
temperature is about 14,000,000ºC
Note that except for our sun, the other stars we see at night are all very
far outside our solar system.
Generally stars other than our sun are visible in the sky only at
nighttime. (There are stars in the sky during the daytime as well, but they are
not visible because the sun’s light is so much brighter.)
Like the sun and moon, the stars (with the exception of those in the
vicinity of Polaris) appear to move across the sky from east to west during the
nighttime.
The nature of space: infinite in extent, a vacuum, no “bottom” or any
absolute or fixed reference for up, down, etc.
Use of exponents and scientific notation is in the fifth-grade pacing guide
for the first quarter. Therefore, it makes sense to introduce and then use this form
of notation when dealing with the large distances in this unit. However, thinking in
terms of “orders of magnitude” is likely to be both new and difficult for most
students. Therefore, use both methods of expressing comparative amounts (e.g.,
the sun is two orders of magnitude larger the earth; that means it is on the order
of 10x10 or 100 times larger, not simply twice as large).
Students can use mathematical ideas and skills like division, ratios, and
proportion to create scale models of the earth-moon and earth-moon-sun systems
in terms of both sizes and distances.
This unit provides rich opportunities to use MEGOSE (pp. 145-146)
“connecting themes” like systems, models, constancy, patterns of change, and
scale.
5a Astronomy Unit Content
2001.09.28 [RTSmith]
Revised 2002.09.09
Summary of
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Atmosphere (presence or lack of)
Composition
Distance
Emits or reflects light and heat
Gravity
Life present or not
Location
Motions (e.g., apparent versus actual; rotations and orbits)
Shape
Size
Surface features
Temperature
Type of object (e.g., star, planet)
Visibility (when, where, shape, size, color, apparent motions)
Water (presence or lack of)
Much of the above information could usefully be represented in a Venn diagram.
Students will be able to make, record, and then clearly share accurate results from “naked-eye”
observations of objects in the sky (e.g., clouds, planes, sun, moon, stars). They will use their
recorded observations to find patterns in the apparent motions of these objects, and be able to link
these observations and patterns to their understanding of the actual size, shape, relative positions,
and motions of these objects. For example, naked-eye observations can be used to collect evidence
that support the conclusion that clouds and planes are closer to us than are the sun and moon.
Students will be able to describe both the apparent and the actual motions of the sun, earth, moon,
and stars relative to one another. Essentially, the apparent motions of the sun, moon, and stars are
across the sky from east to west. From day to day, the sun (as well as the other stars) rises and sets
in about the same locations and at about the same times, and follows the same path between these
two points as it moves across the sky. This is the observed movement of the sun and stars across
the sky. Only by collecting data over several weeks or months will changes in these positions, paths,
and times become apparent. The moon follows a similar pattern in that it rises in the east and sets in
the west and follows essentially the same path across the sky from day to day. However, the times for
the rising and setting of the moon change significantly from day to day. This is the observed
movement of the moon from day to day in the sky.
The actual motions of the earth and moon are that the moon goes (or revolves) around or orbits the
earth roughly once a month, the earth (along with the moon) goes (or revolves) around or orbits the
sun once a year, and the earth spins (or rotates on its axis) once per day (or every 24 hours). [Note
that in everyday language we often use the term “day” in two different ways, sometimes referring to
the period of daylight when the sun is above the horizon and sometimes referring to the entire 24-hour
period. For clarity in this unit, students should refer to the period of time when the sun is above the
horizon as “daytime” and use the word “day” to refer to the entire 24-hour period. With this
perspective, the key concept of “length of day” in the MCF (2000) benchmarks would refer to the 24hour period. Similarly, “nighttime” will be used to refer to period of time when the sun is not above the
horizon.] The intervals for these various cyclic motions can be related to the intervals indicated by a
calendar (i.e., day, month, and year).
Students’ descriptions will include creating accurate representations (e.g., diagrams, physical models)
of the relative sizes of the sun, earth, and moon and the distances between them. Students will be
able to use their descriptions and representations to account for observable phenomena or events like:
the apparent motions of the sun, moon, and stars across the sky from east to west; the apparent
equal size of the sun and moon when viewed from the earth’s surface; the cycle of daytime and
nighttime; the changing shape from day to day of the portion of the moon that we see as being
illuminated; and the changing time of day at which we can see the moon over the course of its orbit.
Similarly, students can use their observations, descriptions, and representations to make predictions
about when the sun and moon will be visible in the sky and how they will appear (e.g., in terms of size,
apparent shape, and position).
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Handout #4
5a Astronomy Unit Content
2001.09.28 [RTSmith]
Revised 2002.09.09