Assignment 7_2390F23
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School
University of Ottawa *
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Course
2390
Subject
Astronomy
Date
Dec 6, 2023
Type
Pages
5
Uploaded by PresidentDuckMaster968
Chapter 11:
1:
How does the darkness of the night sky tell you something important about the universe?
A:
Observations of the dark night sky, including Hubble's Law, the cosmic microwave
background radiation (CMB), the distribution of galaxies and large-scale structure and stellar
evolution provide valuable insights into the evolution and age of the universe. These
observations support the Big Bang theory and allow scientists to estimate that the universe
originated from a single point approximately 13.8 billion years ago. The measurement of cosmic
expansion through Hubble's Law helps determine the rate of the universe's expansion and its age.
The darkness lets us know that there is an existence of several astronomical objects millions of
miles away in the universe. As the earth revolves and rotates around the sun in its own orbit,
there is more scope to explore every part of the universe during night times as the sky is darker.
If the proximity of two planets revolving around the sun is closer, then the darkness of the night
sky shows the existence of the planets in close proximity. The darkness of the night sky also
indicates that the universe is not infinitely old. Had this been the case, every other point in the
sky would be the same as the surface of a star in terms of brightness. This is referred to as
Olber’s paradox which confirms to astronomers that the universe did originate from somewhere
and is continuously evolving.
2:
Why can't the universe have a centre?
A:
Modern observations suggest that the universe may be infinite and without end. The edges of
galaxies, global clusters, oceans, pizzas, and other objects can be used to locate their centres. As
a result, the universe cannot have a center because this establishes logical consistencies to the
universe and it lacks an edge. Furthermore, the lack of an absolute coordinate system, combined
with the universe's expansion, makes determining a definite centre impossible.
8:
What is the evidence that the universe was very uniform during its first 400 OOO years?
A:
During the first 400,000 years, temperatures of the universe dropped to 3000 K and protons
could capture and hold onto the free electrons to form neutral Hydrogen atoms (Called
recombination). The free electrons held by the atoms were unable to deviate from the photons.
The gas became transparent since the photons could easily pass through it. Photons maintained
the same blackbody temperatures as gas and photons were in recombination. These photons are
observed in the cosmic microwave background (CMB). Cosmic background radiation is isotropic
or uniform in all directions, the universe must have been remarkably consistent during its first
400,000 years. The early homogeneity is primarily due to the inflationary period.
Learning to Look 1:
A:
The microwave background irregularities determine the nature of spots at different angular
sizes. The calculations conform to the spots which are one degree in diameter. The size and
position bring a better understanding of the age, acceleration and expansion of the universe. The
irregularities in the background radiation give evidence for the flat universe. If the universe is
open, then the most common irregularities would be smaller. And if the universe is closed, they
should be bigger. During the very early stages of the universe, it was dense enough for sound to
travel through the gas. The result of this is that the big bang did in fact make a noise. These
powerful sound waves determined the size of the irregularities which are now found in the
cosmic microwave background radiation.
Chapter 12:
1:
What produced the helium now present in the Sun's atmosphere? In Jupiter's atmosphere? In
the Sun's core?
A:
The Big Bang Theory is one of the most reliable models of the formation of the universe
which answers many questions about the formation of the sun and other planets of our solar
system. This model states that it is formed by the high density and temperature that makes the
universe possible in many states. Most of the formation of helium from the Sun's and Jupiter's
atmosphere was produced briefly after the Big Bang. Some of it is produced by nuclear fusion in
the stars (within the Sun's core and is responsible for the production of large-scale helium in the
same atmosphere).
3:
What is the evidence that the solar system formed about 4.6 billion years ago?
A:
The solar system formed about 4.6 billion years ago due to the gravitational collapse of a
small part of a molecular cloud which centred forming the sun while the rest flattened forming
the planets, asteroids, moon out of the proto-planetary disk. The radiometric dating method of
measuring the half-life is used for the calculation of the earth. Since all organisms take in C-14, a
constant level of isotope is maintained by all organisms. This method of radioactive dating has
been successful in determining the age of the earth, accordingly, comes to around 4.5 billion
years. “The entire solar system formed in about 100 million years” can be explained by the fact
that the entire mass about 99.9 percent of the solar system is concentrated in the sun alone which
makes it possible for the solar system to stop dissipating further away. The radioactive dating of
various elements on Earth determined that the Earth's oldest rocks are approximately 3.9 billion
years old. By assuming that the sun and planets formed simultaneously, the Earth and solar
system must be at least 3.9 billion years old. This assumption keeps the solar nebula theory in the
equation, which describes the overall appearance and structure of our solar system. The
radioactive dating of rocks on the moon determines that the rocks are approximately 4.48 billion
years old, the radioactive dating of rocks on Mars determines that the rocks are approximately
4.5 billion years old, the radioactive dating of meteorites determined that they were about 4.6
billion years old, suggesting that the solar system must be at least 4.6 billion years old. Dating of
the oldest rocks from Earth and the Moon shows lesser ages but they are consistent with the
estimations from the meteorites.
5:
Why does the solar nebula theory predict that planetary systems are common?
A:
The solar nebula theory predicts that planets form as a natural byproduct of star formation. As
the cloud collapses to form a star, small planetesimals form. These small planetesimal accrete
(combine) matter to form planets. As said, planets form from the gases that surround a newly
formed star. Planet formation is a natural process associated with star formation. As a result, the
theory suggests that the majority of stars should have a planetary system. As a star forms, the
leftover gas and dust in the surrounding region coalesce to form planets. The planets were
formed simultaneously yet they differ in composition. The planets that formed near the Sun
contain metallic iron and a few minerals with very high temperatures and little gas. These planets
are Mercury, Venus and Mars. The planets that formed far from the Sun have low temperatures
and materials in the cloud do not get condensed. As a result, they contain massive amounts of
hydrogen. These planets are Jupiter, Saturn, Uranus and Neptune.
8:
What does the term differentiated mean when applied to a planet? Would you expect to find
that planets are usually differentiated? Why?
A:
Differentiation is the process by which gravity helps separate a planet’s interior into layers of
different compositions and densities. The heavier metals sink to form a core, while the lightest
minerals float to the surface to form a crust. Later, when the planet cools, this layered structure is
preserved. In order for a rocky planet to differentiate, it must be heated to the melting point of
rocks, which is typically more than 1300 K. When applied to a planet, differentiation means the
restructuring through density. Planets are normally differentiated due to a bombardment of
meteorites or other structures that affect the atmosphere (global warming). In the Terrestrial
planets, the denser materials sink to the center of the Earth and the heat creates a molten core.
Yes, it is expected to find planets that are usually differentiated because the stability relations are
not identical and components will migrate from less stable conditions to more stable conditions.
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It is an important aspect of the solar nebula theory. If planets formed in a manner similar to that
proposed by the theory, then planets should be differentiated.
9:
What are asteroids and comets, what are their connections to meteors and meteorites, and
what clues do they give about the origin of the solar system?
A:
Asteroids and comets are both celestial objects that orbit the Sun. Asteroids are primarily
found in the asteroid belt, a region between Mars and Jupiter. They are composed mainly of
metals and rocky materials that vary in size from a few meters to hundreds of kilometres in
diameter. Comets are icy bodies with a nucleus made of dust, frozen gases, water, ice and other
organic compounds. When they approach the Sun, they develop a glowing coma and a tail due to
the sublimation of the ice. Comets come from the distant reaches of the solar system, like the
Kuiper Belt and the Oort Cloud. Their connection to meteors and meteorites helps scientists
uncover these mysteries and learn more about our cosmic origins. Meteoroids are smaller
fragments of asteroids or comets that travel through space. When a meteoroid enters Earth's
atmosphere and burns up due to friction, it creates a streak of light known as a meteor or
"shooting star." If a meteoroid survives its journey through the atmosphere and lands on Earth's
surface, it is called a meteorite. These objects are remnants from the early solar system, dating
back billions of years. By studying them, scientists can gain insights into the conditions and
processes that led to the formation of our solar system. Asteroids and comets are considered the
building blocks of the solar system. They contain materials that have remained relatively
unchanged since the solar system's formation, providing clues about its chemical composition
and the processes that shaped it. Studying comets can shed light on the delivery of these vital
ingredients for life to Earth and other planets. The study of impact craters and the analysis of
meteorites can help us understand past impacts and their effects.
Learning to Look 2:
A:
The rings around the planet in the image indicate that this planet formed far from the Sun.
When a planet is far from the Sun, the ring particles are not swept away as quickly by radiation
pressure and solar wind. If the planet were closer to the Sun, solar wind and radiation pressure
would drive ring particles away. The fact that this planet has rings indicates that it must be a
massive planet. Massive planets tend to form far from the Sun due to the outer regions of the
solar system having more material available for planet formation. As a result, the presence of
rings around the planet indicates that it is far from the Sun.