ASTR 101 Lab 4 - Lunar
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University of Victoria *
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101
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Astronomy
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Jan 9, 2024
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March 9, 2023
ASTR 101 Lab 4 - Lunar
Objective
The objective of this lab is to observe the various craters and maria on the
surface of the Moon. We can understand the Solar System by observing the surface of
the Moon and Earth. And we can also learn about the origins and evolution of planetary
systems and natural satellites.
Introduction
The moon is the source of light at night. Through its phases such as the full
moon, new moon and many more, early civilizations can use it as a method of tracking
time. Earth’s natural satellite orbits in a monthly period. Or more accurately 29.53 days.
We use the moon’s orbit to track each month just as we use Earth’s orbit around the
Sun to track years. It is also tidally locked with Earth. Which means it plays a role in
changing the tides of bodies of water on Earth. Thanks to today’s technology and
several missions to space, whether by humans or rovers, we learned so much by
studying the lunar surface. It’s because of these discoveries that we can learn so much.
Each crater and mare have different aspects which can help us better understand the
solar system. And there is so much still to learn.
Procedure
This lab required me to use a photo editing tool and the high-resolution image of
the moon that was provided. For the first part, Using the photo editing tool (I used the
photo editor on my laptop instead of GIMP but I used GIMP for measuring), I located,
identified and labelled prominent craters, parts of the maria and several spacecraft
landing sites. For the second part, I used GIMP’s measuring tool to measure the
diameter of the moon and craters in pix, then use those numbers with the actual
diameter of the moon to get the km/pix ratio. For the third part of the lab, I used the
Impact Earth link as well as the given parameter such as the velocity and angles to
calculate the size of the meteor based on the dimensions of its crater. Impact Earth was
also used to see what kind of geographic phenomena like earthquakes and tsunamis
would occur if a meteor hit Earth.
Observations and Figures
The figure below (Figure 1) is a high-resolution image of the moon. Craters, maria and
space landing sites have been labelled. All observations about the moon’s surface will
be answered in the “Answers” section.
Figure 1 - Lunar Image
Answers
1.
Refer to figure 1 and/or the pdf file.
○
Blue
for the mares,
○
Orange
for craters
○
Green
for the spacecraft landing spots.
2.
Overlapping craters are labelled in
purple
: Theophilus and Cyrillus.
3.
Craters before and after the mare
○
Before Mare in
pink
: Archimedes
i.
This crater has a flat and smooth surface
ii.
The central uplift has been covered by the Maria
○
After Mare in
pink
: Langrenus
i.
Langrenus still has the middle of the crater still visible (central uplift)
ii.
It is not as smooth as Archimedes
4.
Found 2 craters in
cyan
: Copernicus and Kepler, they both are very prominent
craters and have white streaks coming from them.
5.
3476km/1180pix =
2.94576km/pix
6.
Big and Small Crater
○
Plato (bigger crater): 32pix x 2.9457km/pix =
94.2644km
○
Kepler (smaller crater): 7pix X 2.9457km/pix =
20.62033km
7.
Crater diameter km = 50 x (diameter of meteorite km)
○
For Plato, by the rule of thumb, the crater is 94km. Therefore (94km /
50km = 1.88km). The meteors would've been
1.88km
, nearly 2km.
○
For Kepler, the crater is 20km. Therefore (20km / 50km = 0.4km). The
diameter of the meteor would have been
0.4km
.
8.
Crater Size Comparision (the craters are labelled in
brown
in Figure 1)
○
Jerik is 0.63 km in diameter. This is a similar size to Barringer crater which
is 1.2km. This was tricky to find since it was so small. It is located in the
southeastern part of the Mare Serenitatis.
○
Alphonsus is 119km in diameter. This is a similar size to the Manicouagan
crater which is 100km.
○
Von Karman is 180km in diameter. This is the same size as the Chicxulub
crater which is 180km.
9.
Apophis and Swift-Tuttle
●
Apophis:
○
Distance from Impact: 300km
○
Projectile Diameter: 325m
○
Density: 2600kg/m^3
○
Impact Velocity: 10km/s
○
Impact Angle: 45 deg
○
Water Depth: 3000m
○
Rock: Crystalline
Using Earth Impact, the diameter of the Apophis crater is
3.67km
and
438m
deep.
●
Swift-Tuttle:
○
Distance from Impact: 300km
○
Projectile Diameter: 26km
○
Density: 1000kg/m^3
○
Impact Velocity: 50km/s
○
Impact Angle: 45 deg
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○
Water Depth: 3000m
○
Rock: Crystalline
Using Earth Impact, the diameter is
297km
and
1.61km
10. Almost of the inputs were provided in the Lab manual. When I looked up the
density of 99942, it was 2.6g/m^3 or 2600kg/m^3. And the average angle of
impact of a meteorite is 45 deg.
11. Apophis and Swift-Tuttle
Apophis
:
○
Distance from Impact: 300km
○
Projectile Diameter: 325m
○
Density: 2600kg/m^3
○
Impact Velocity: 10km/s
○
Impact Angle: 45 deg
○
Water Depth: 3700m
Tsunami would be less than 6.3m
Swift-Tuttle:
○
Distance from Impact: 300km
○
Projectile Diameter: 26km
○
Density: 1000kg/m^3
○
Impact Velocity: 50km/s
○
Impact Angle: 45 deg
○
Water Depth: 3000m
Tsunami would be 1.2km - 2.4km in height (like the Interstellar wave
scene)
12. You would be safe if Apophis hit because the tsunami won’t even touch the top
of Mount Doug as it is less than 6.3m. However, if Swift-Tuttle hit, then you would
NOT be safe since the wave would be 1.2km - 2.4km high.
13. 1km Asteroid
○
Distance from Impact: 300.00 km
○
Projectile diameter: 1000.00 meters
○
Projectile Density: 3000 kg/m3
○
Impact Velocity: 10.00 km per second
○
Impact Angle: 45 degrees
○
Target Density: 2750 kg/m3
○
Target Type: Crystalline Rock
The size of the crater is
10.7km
and
604m
deep
14. When I was observing the image of the moon, I noticed that there were more
craters on the lunar surface than on maria. This observation leads me to believe
that more craters formed during the early day of the Solar System’s history.
15. Maria coverage of total lunar surface = 16%
○
Total number of craters = (100/16) x # of craters in maria
○
I estimate that there are 120 craters in the lunar maria. I made this
assumption because when I looked up the number of craters in the maria,
the answer was over 100.
○
Total # of craters = (100/16) x (120) =
750
total craters
16. Rate of collision = Age of Maria / # of craters
○
Age of Maria = (3.1 billion years + 3.9 billion years) / 2 = 3.5 billion years
○
Rate of collision = 3.5 billion years / 750 asteroids =
46666667
years per
asteroid
17. Average asteroids = # of craters/age of Maria
○
Average asteroid = 750 asteroids / 3.5 billion years =
2.14 x 10^-7
asteroids per year
18. Average asteroids rate on Earth = ((area Earth) x (moon rate)) / (area moon)
○
Average asteroid rate on Earth = ((510 million) x (2.14 x 10^-7)) / (38
million) =
2.88 x 10^-6
asteriods per year
19. Any impact made on the moon will show up on its surface because there is no
atmosphere protecting the moon. Based on the number of craters on the Monn’s
surface, it is safe to estimate that it has been hit a lot. Compared to Earth, a lot of
meteors and space debris crash into Earth. However, only the larger ones that
don’t burn up upon entry into Earth’s atmosphere will leave a mark on the Earth’s
surface. It’s possible that Earth has been hit or was about to be hit just as much
as the Moon, but due to the atmosphere and other terrestrial factors like wind,
weather and tectonic activity, there’s no way of knowing. We can only count the
big meteors that have yet to be covered/hidden.
20. Human civilization is 6000 years old. The last catastrophic meteor that wiped out
all the dinosaurs occurred 65 million years ago. Once every 500 million years,
there will be a major mass extinction asteroid that will hit Earth. Since the last
one was 65 million years ago, the next one will not happen for another 435
million years.
21. A lot of the craters on Earth are covered by dust. Due to erosion, and tectonic
activity such as earthquakes, it is possible that many craters on Earth have been
covered. The bigger craters would take more time to disappear which is why
evidence of bigger craters is still visible. We also need to consider that the moon
has no atmosphere, no weather, no water, no wind or means to cover up craters.
That’s why the moon’s surface is unchanged. We can use the craters to calculate
how many asteroids have made an impact on the Moon.
Discussion
During this lab, I examined the aspects of the Moon’s surface. From the
high-resolution image that was provided, it appears that there are more craters on one
side of the moon which leads me to believe that the moon had a higher rate of objects
making impact on the surface as opposed to today. But there are still meteors creating
craters today.
For question 13, I assumed that the diameter of the meteorite was 1km and used
that to calculate the size of the crater. When I did my own research, I found that the
angle of impact for most meteors is 45 deg. Since the distance from the impact site
does not matter in this case, I chose 300km since it is the same distance as the other
asteroids from the lab (Swift-Tuffle and Apophis). The average velocity of an asteroid is
18km/sec, and since the asteroid I came up with is in the medium to small range, I
chose 10km/sec to be its velocity. The density can be 3g/cm^3 to 4g/cm^3. I assumed
that the density of the meteorite is 3000kg/m^3 since its diameter of it was relatively
small. As for the type of rock target, I selected crystalline rock since it’s similar to the
surface of the moon.
Some errors would have been found when I was using GIMP to measure the
diameters of the craters. Since I was using a trackpad on my laptop, it was tricky to
create a straight line. And because of this, it is possible that some of my previous
calculations were not completely accurate. Another error would’ve been the count of the
craters. Since there were many tiny craters, I could have missed them. That is why I
made an estimate. This all could’ve caused inaccurate data.
Conclusion
I learned a lot from this lab. For example, I learned that there are different types
of craters on the moon and you can use them to estimate when the meteor made an
impact on the moon as well as the meteor’s size. When doing my own research, I
learned of the moon is slowly drifting away from Earth’s orbit. But by the time the moon
gets too far that it affects the tides, humanity would’ve died out. And that the average
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angle of a meteor impact is 45 deg. I did not know that objects crashing into the Earth
hit at an angle. This lab has expanded my knowledge of the moon and its properties.
References
J. Mehta, “The Landing Site of NASA Apollo 11”, in Jatan’s Space. [Online]. Available:
https://blog.jatan.space/p/apollo-11-landing-site
[Accessed: July 18, 2020]
B. King, “How to See All Six Apollo Moon Landing Sites”, in Sky and Telescope.
[Online]. Available:
https://skyandtelescope.org/observing/how-to-see-all-six-apollo-moon-landing-sit
es/
[Accessed: April 15, 2015]