Astronomy of Solar System (AST-121) Homework: Earth and Moon Analysis

This astronomy homework assignment, covering Chapters 9 and 10, explores the Earth and the Moon. It begins by identifying the Earth's layers, determining the densest layer, and calculating the movement of tectonic plates. The assignment then investigates the sources of Earth's atmosphere and the process of how the sun heats the atmosphere, along with the impact of greenhouse gases on temperature. Chapter 10 shifts focus to the Moon, detailing observable features like mountains, impact craters, and maria, while explaining their formation processes. The assignment also describes the leading theory for the Moon's formation and explains why golf balls travel further on the Moon compared to Earth. The assignment includes detailed calculations, descriptions, and explanations based on scientific concepts and theories.

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Geography
Astronomy of Solar System
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Homework questions
Chapter 9.
1. The question requires the main layers of the earth, and the densest layer.
There are three (3) main layers of the earth;
 Core is closest to the center of the earth and is made up of the inner core and outer core.
 Mantle is composed of the lower mantle and upper mantle.
 Crust is the less dense layer made of the oceanic crust and the continental crust.
Out of these three layers, the inner core has the highest density.
2. If the sea floor of Eurasian and North American plates has drifted apart by 60km in a
period of 3.3 million years, how far do they move apart in one year?
Working
Conversion of units: 60 km is equivalent to 60,000,000 mm = 6 x 107 mm
3.3 million years is equivalent to 3,300,000 years= 3.3 x 106 years
If the plates drift apart in 3,300,000 years by 6 x 107 mm, what will be the drift in 1 year?
Drift = 1 year∗6 x 10 ˄7 mm
3.3∗10 ˄6 years = 18.18 mm/year
Therefore, the Eurasian and North American plates move apart by 18.18 mm every year.
3. The question requires the three main sources of the present-day earth’s atmosphere.
The three main sources of the atmosphere are gases (mostly Nitrogen, Oxygen, argon and
carbon), water vapour and dust particles.

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4. In this question, a description is required of how the sun heats the lower part of the
atmosphere in a sequential process.
Since the sun is very hot, it releases short-wave radiant solar energy. A short-wave radiation has
shorter wavelengths and high energy. This radiation travels through space and reaches the earth
surface.
The earth surface and objects on it absorb the solar energy and re-emits it in form of long wave
radiation (infrared light). Due to energy losses, the long wave radiation has lesser energy. This
re-emitted energy by the earth then heats up the lower part of the atmosphere (Abdusammatov).
It should be noted that even clouds and other objects on or near the earth surface also absorbs the
short-wave terrestrial radiation and re-emits it back to the atmosphere. This can be through
radiation, conduction and convection. The heat from sun passes through the atmosphere and
reaches earth’s surface by radiation. The movement of wind transfers heat by convection from
the earth’s surface to the atmosphere, warming it.
5. The question requires an explanation on the effect of greenhouse gases on temperature of
the earth.
Green house gases are able to absorb and emit radiations. The shortwave radiation from the sun
reaches the surface of earth and is re-emitted in form of long waves. The greenhouse gasses then
absorb the heat and re-emits them again increasing the temperature of the atmosphere. Since they
capture the heat from earth’s surface, there is lesser heat leaving from the atmosphere as most of
it is trapped and not released to the space. This accumulation of heat on the atmosphere results
into higher temperatures, a phenomenon called global warming (Kweku).

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Chapter 10
1. This question requires a description of the three features on the moon that can be seen
using a telescope.
The three main features of the moon are mountains (highlands), impact craters and maria
(seas).
The impact craters on the earth’s moon are formed by impacts of high-speed space
objects hitting the moon, totaling to 5185 craters spread across 12 miles. The moon is like
a desert with valleys and mountains, of interest are the Mons Piton and the Mons Pico.
Marias are also featuring on the moon, formed by ancient volcanic eruptions and are
called “seas”.
2. The process of how Maria was created, and why the far side has lesser Maria than the
near side.
3.9 billion years ago, as the moon cooled and solidified during its formation, some areas sunk
forming depressions on the surface of the moon. These sunken areas were then filled with
outpouring lava to form Marias or “seas”. Since there is no water in the moon, these areas
were filled by lava during the ancient Lunar volcanism (Nissani). Another theory postulates
that these low altitude areas where maria are formed were created due to the bombardment of
asteroids and other objects with the surface of the moon.
The near side of the moon has thinner crust, which allowed for more volcanic activities in the
ancient time, resulting to more craters and maria. This explains why there are fewer Maria on
the far side of the moon, as it has thicker crust that did not allow for much volcanic eruptions.

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3. Formation of the mountains on the moon.
The mountains on the moon were purely formed by the impacts of large asteroids and other
space debris hitting the surface of the moon. This is because the moon does not have tectonic
plate movements or volcanic activities, thus mountain ranges and highlands were as a result
of impacts and collisions with steroids.
4. Description of the leading theory for the formation of earth’s moon.
The leading theory for the formation of the moon is the Giant-impact hypothesis, also called
the Big-Splash. It suggests that the moon was formed when an object smashed into early
earth, throwing vaporized chunks of earth into space. The particles were then bound together
by gravity, forming the moon. Since the materials that formed the moon after collision came
from crust, it is less dense than the earth.
5. Why golf balls hit on moon travelled further than they would on earth.
 There is less gravitational pull on the moon (one-sixth of the earth’s gravitational
pull) therefore the balls travel further before being acted upon by the force of gravity
as compared to earth.
 There is no atmosphere on the moon, therefore no air resistance. With no force
impeding the ball from forward movement, the golf balls traveled further than if they
were to be hit on earth’s surface.

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References
Abdussamatov, Habibullo I. "The Influence of the Atmospheric Transmission for the Solar
Radiation and Earth's Surface Radiation on the Earth's Climate." Journal of Geographic
Information System 2.4 (2010): 194-200 .
Kweku, Darkwah Williams. "Greenhouse Effect: Greenhouse Gases and Their Impact on Global
Warming." Journal of Scientific Research and Reports 17.6 (2018): 1-9.
<https://www.researchgate.net/publication/323223192_Greenhouse_Effect_Greenhouse_
Gases_and_Their_Impact_on_Global_Warming>.
Nissani, Moti. "Phases of the Moon." Journal of Science Activities 31.3 (1994): 26-29.
Xuelong Chen, Juan A. An and Zhongbo Su. "The Deep Atmospheric Boundary Layer and Its
Significance to the Stratosphere and Troposphere Exchange over the Tibetan Plateau."
8.2 (2013).
<https://www.researchgate.net/publication/235757845_The_Deep_Atmospheric_Bounda
ry_Layer_and_Its_Significance_to_the_Stratosphere_and_Troposphere_Exchange_over_
the_Tibetan_Plateau>.