Challenge Question #1
Challenge Question #2
Challenge Question #3
Challenge Question #4
Challenge Question #5
Challenge Question #6
Astronomers measure the apparent size of celestial objects using
Just as a circle contains 360 degrees, you can see what one degree on the sky
looks like by slicing the horizon into 360 slices.
From Earth, the moon’s apparent diameter is half a degree. What is the
apparent diameter of the Earth as seen from the moon?
Earth diameter = 12,756 km
moon diameter = 3,476 km
Ratio Earth/moon = 3.67
Apparent diameter of Earth as seen from the Moon = 0.5 degrees x
3.67 = 1.84 degrees
Congratulations! Our winner is from Bern Homeschool,
Look at the moon and notice that there are two different kinds
of terran: bright areas and dark areas. How are they different,
besides their color? What are the compositions (rock types) of the
bright and dark areas of the moon? What are the Latin words scientists
use to refer to these areas, and what do they mean?
The bright areas are rugged highlands. The
dark areas are relatively smooth lowlands. The bright areas are
made of shattered and crushed rock called breccia (BREHCH ee uh);
the dark areas are made of volcanic rock called basalt (ba SAWLT). The Latin name for
the highlands is terrae (TEH ree) which means “land.” The
Latin name for the lowlands is maria (MAH ri uh), which means “seas” (because
ancient astronomers thought they were literally seas filled with
Source: Spudis, Paul D. "Moon." World Book Online
Reference Center. 2004. World Book, Inc. http://www.nasa.gov/worldbook/moon_worldbook.html
Congratulations! To Ms. Stoica's 9F class for
submitting the winning answer to Question #2
How old are the oldest rocks found on the moon?
How old are the oldest rocks found on the Earth?
Why don’t we find rock on the Earth as old as those on the moon?
Answer: The oldest rocks brought back by the Apollo astronauts
are about 4.5 billion years old; this is just 100 million years younger
than the time of the solar system’s formation 4.6 billion years
ago. The oldest rocks found on Earth are about 4.0 billion years old—not
because the Earth is any younger than the moon (in fact, it’s
a bit older), but because the first half-billion years of Earth’s
history has been erased by vigorous geologic activity, especially
the restless shifting of the continents called plate tectonics. On
the moon, where most geologic activity ceased around 3 billion years
ago, rocks from the earliest 500 million years of its history are
Congratulations! To Jacob and Kenny from Ms. Nelson's class
for submitting the winning answer to Question #3
a. Why don’t we see the far side of the moon from Earth?
b. Explain the difference between the far side and the dark side.
a. The force of gravity exerted by a celestial body is stronger
for objects that are closer to it, and weaker for objects that
are farther away. In the case of the Earth and moon, the Earth's
gravitational pull is slightly stronger on the side of the moon
facing the Earth, and slightly weaker on the side of the moon
facing away from the Earth. The imbalance creates a so-called
tidal force that creates slight bulges in the moon's shape.
Initially, the moon's rotation was faster than it is today,
but over time, the gravitational pull on these bulges slowed
the moon's rotation, until today, the moon rotates at the same
rate as it's orbit around the Earth. (This process was also
helped by the fact that the moon's center of mass is actually
a bit closer to the near side than it is to the far side.) As
a result, the moon always presents the same side to the Earth.
We call the part of the moon facing away from the Earth the
b. As the moon circles the Earth, making one rotation during each orbit, the
sun shines on all portions of the moon. At any given moment, the side facing
away from the Sun is called the dark side. This is not the same as the far side,
which is sometimes in sunlight and sometimes in darkness.
Congratulations! Ms. Stoica's 9I class for submitting
the winning answer to Question #4
- Assume it costs $100,000 to transport one pound (Earth weight)
of supplies from Earth to a base on the surface of the moon.
- Assume each astronaut requires 0.8 gallons of water on any day
when that astronaut remains inside the base all day, and 1.2 gallons
of water on any day when the astronaut goes outside for a seven-hour
moonwalk, working inside a pressurized space suit.
- Assume each astronaut does a moonwalk every other day (so that
half the crew does a moonwalk one day, the other half does a moonwalk
the following day, and so on). Questions:
- For an early lunar expedition
with 4 people staying on the lunar surface for 8 days, how much
does it cost to carry enough water for the crew’s stay on
the lunar surface?
- For a lunar base crew of 6
people, living on the moon for 180 days, how much does it cost to
supply the base with enough water, carried from Earth, for that
- To save the cost of transporting
water from Earth, suggest one way that astronauts on the moon might
obtain water locally, assuming there is NOT any ice buried under
On any given day, half the crewmembers each
use 0.8 gallons of water and the other crewmembers each use 1.2
gallons. If the total number of crewmembers is N, this becomes ((N/2)
x 0.8) + ((N/2) x 1.2) = N gallons per day total for the entire
- For the 4 person crew, the total water usage per day is 4 gallons.
For the entire 8-day lunar stay, the total water usage for the entire crew is
Multiplying by the weight of a gallon of water, 8.35 pounds (Earth weight), we
32 x 8.35 = 267.2 pounds (Earth weight).
Multiplying by $100,000 per pound, we get a cost of $26,720,000
- A six-person crew uses 6 gallons of water each day. Over 180 days the total
usage is 1,080 gallons weighing 9,018 pounds (Earth weight). This translates
to a cost of $901,800,000.
One way to obtain water on the moon would be to combine oxygen and hydrogen
obtained from lunar rocks and soil.
Over billions of years hydrogen has been deposited in lunar soil as part of the
steady stream of subatomic particles from the Sun called the solar wind. Releasing
hydrogen can be accomplished by heating lunar soil to a temperature of 700 degrees
Centigrade. (One way to create the necessary heat might be to focus sunlight
with curved mirrors.)
Oxygen, meanwhile, is contained in the mineral ilmenite, a titanium oxide that
is present in lunar rocks (including tiny rock fragments mixed in with the soil).
To release the oxygen, ilmenite is exposed to hydrogen and heated to a temperature
above 800 degrees Centigrade. Once the oxygen is released, it can combine with
the hydrogen to produce water.
Congratulations! to Rogers Home School for submitting
the winning answer to Question #5
Assume that the concentration of ice contained in the lunar soil within permanently
shadowed craters is 2 percent by weight.
- Assume that the ice exists only in the top 2 meters of soil.
- Assume that the density of lunar soil is 2.9 grams per cubic centimeter (Earth
- Scientists have estimated that the total area of
the moon that is permanently in shadow, at both north
and south poles, is 12,500 square kilometers. Based
on the above assumptions, how many gallons of water
are contained in the lunar polar regions?
- Based on the information in Question 5, how many
astronauts, living and working at bases on the moon,
could this much water sustain for a year?
- Do you think it is realistic
to harvest all this water?
Suggest ways to help astronauts
working at a base in the moon’s
polar regions to obtain ice
from lunar soil. Estimate how
much water could be harvested
in one year of base operations.
- -Multiplying the area of 12,500 km” times
the thickness of 2 meters, we get a total
volume of 25 km“ for the ice-rich layer.
-At a density of 2.9 g/cm“ this gives a total weight of 72,500,000,000,000
kg (this can also be written as 7.25 x 10’“ kg)
-If the ice amounts to 2 percent of this value, that gives us 1,450,000,000,000
kg of ice.
-Converting to pounds, we get 3,190,000,000,000 pounds of ice.
-Dividing by 8.35 pounds per gallon, we get 382,035,928,144 gallons of water.
(Of course, slight variations in the value you use
for the number of pounds per gallon
will produce slight variations in the answer.)
Alternatively, we could calculate that 1,450,000,000,000
kg of ice is equal to
1,450,000,000,000 liters of water; then, multiplying
by 0.26 gallons per liter, we get:
Either answer is acceptable.
- From Question 5, we know
that the average water use for astronauts
at a lunar base is 1 gallon per person
per day. Therefore, one person uses
365 gallons of water
To find the number of people that could
be supported by the total amount of
ice on the moon, we divide the answer
from (a) by 365 and we get 1.03 billion
(Again, variations in this answer because
of different methods of calculating
(a) are acceptable.)
- Thanks for all the great ideas
Congratulations! Ms. Stoica's 7th Grade class for submitting
the winning answer to Question #4