AST_101_Lesson_4_Homework_Rev (1)
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Arizona State University, Tempe *
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Course
101
Subject
Astronomy
Date
Feb 20, 2024
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docx
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Uploaded by ProfessorSheep4002
AST 101 Lesson 4 Homework
Student Name: Isabella Brown
Question 1 (4 points) Describe the differences between refracting and reflecting telescopes.
Refracting telescopes use lenses to gather and focus light, while reflecting telescopes use mirrors. Refractors provide sharp, high-contrast images and are low maintenance, but their size is limited, and they can show chromatic aberration. Reflectors, on the other hand, offer lager apertures for better light gathering, higher resolution images, and do not suffer from chromatic aberrations. However, they are bulkier, require regular maintenance, and need longer acclimatization time. Question 2 (4 points): Describe two so-called "spectral windows" in the Earth's atmosphere which allow the transmission of electromagnetic radiation to the Earth's surface. In your answer,
describe the type of telescope used to observe through each window.
The Earth's atmosphere has several “spectral windows” that allow certain wavelengths of electromagnetic radiation to reach the surface. The two main ones are the optical window and the radio window. Optical telescopes, which include both refracting and reflecting types, are used to observe through the optical window. Radio telescopes which use large antenna systems
to collect radio waves, observe through the radio window. Question 3 (10 points): Your cell phone has a camera and a digital detector similar to the CCD sensors used for scientific imaging and research. Describe the differences between your cell phone and a research telescope with a CCD sensor that might limit your cell phone's use for astronomical research.
Your answer should use complete sentences and good grammar.
While both cell phone cameras and research telescopes with CCD sensors capture images, there are significant differences. CCD sensors in research telescopes are designed for low noise levels and high-quality images, while CMOS sensors in cell phones tend to have higher noise levels. Additionally, research telescopes have larger apertures allowing them to collect poor light and offer better views of distant objects. Cell phone cameras, while portable and convenient, are not designed for the detailed, long-distance imaging required in astronomical research. Page 1 of 4
AST 101 Lesson 4 Homework
Question 4 (8 points): Provide several reasons astronomers locate observatories on mountains far from urban areas.
Observatories are often located on mountains for several reasons. The thin atmosphere at high altitudes results in less atmospheric interference and clearer observations. Secondly, these locations are usually far from urban areas, reducing light pollution. Lastly, being above some of the turbulent atmosphere minimizes image distortion caused by air turbulence.
Question 5 (4 points): Explain the scientific advantages of placing telescopes in Earth's orbit.
Placing telescopes in Earth's orbit offers several scientific advantages. It allows observation of the full electromagnetic spectrum, including wavelengths absorbed by the Earth's atmosphere. It
eliminates the distortion caused by the Earth's atmosphere, enabling higher resolution imaging. Lastly space-based telescopes can operate continuously, not being limited by day-night cycles or weather conditions. Question 6 (8 points, 2 points each): Describe the significant differences between terrestrial planets as a group and the Jovian planets as another group. Compare the following 4 properties:
A)
Composition:
Terrestrial planets including Mercury Venus Earth and Morris have solid rocky surfaces and are primarily composed of silicate rocks and metals. In contrast Jovian planets namely Jupiter Saturn Uranus and Neptune are characterized by their gaseous composition primarily of hydrogen and helium.
B)
Size:
Terrestrial planets are significantly smaller than Jovian planets. For instance, earth the largest terrestrial planet is dwarfed by Jupiter, the largest Jovian planet which has a radius approximately eleven times that of Earths.
C)
Orbital properties:
Terrestrial planets orbit closer to the sun resulting in a shorter orbital period. On the other hand, Jovian planets being farther from the sun have a longer orbital period.
D)
Existence of satellites or rings:
While terrestrial planets have few or no moons, Jovian planets have a higher number of satellites. Additionally, Jovian planets like Jupiter and Saturn have rings of dust and debris orbiting them, a feature not seen in terrestrial planets.
Question 7 (5 points): Describe several properties of the solar system that support the nebular model in which planets of our solar system condensed from a spinning mother cloud spun away from the young Sun.
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AST 101 Lesson 4 Homework
The nebular model which posits that the solar system formed a spinning cloud of gas and dust, is supported by several properties of the solar system., the planets in our solar system all orbit the sun in the same direction, which is consistent with the rotation of the original nebular disk. Secondly the planets are roughly aligned on a plane, which is what we would expect if they formed from a flattened disk. Rocky plants closer to the sun and gas giants farther away, which can be explained by the temperature gradient in the nebular disk.
Question 8 (4 points): Describe the difference between Earth and Mars that allowed the Earth to
retain an atmosphere whereas Mars lost its atmosphere.
Earth and Mars differ significantly in their atmosphere due to their size in geological activity. Come up being larger, has a stronger gravitational pull that helps retain its atmosphere. Additionally, Earth's active geology through processes like volcanic eruptions continually replenishes the atmosphere. Myra's come a being smaller, has a weaker gravity and less geological activity, which makes it less capable of retaining and replenishing its atmosphere.
Question 9 (4 points): Describe how the ages of rocks may be determined using radioactive elements.
The ages of rocks can be determined using a technique called radiometric dating, which relies on the decay of radioactive elements. Each radioactive element decays at a known rate, transforming into a different element over time. By measuring the ratio of the original radioactive
element to its decay product in a rock sample, and knowing the half-life of the parent, scientists can calculate the age of the rock.
Question 10 (4 points): Would you expect as many impact craters per unit area on the surface of Venus as on the surface of Mars? Why or why not?
Venus and Mars differ in the number of impact critters per unit area due to their different geological activities. Venus has fewer craters than Mars because its active geology resurfaces the planet, erasing many craters. Mars, with lest geological activity, preserves its craters for a longer time. Therefore, we would expect to see fewer impact craters per unit area on the surface of Venus compared to Mars. Question 11 (5 points): A radioactive nucleus has a half-life of 5 × 10
8
years. Suppose a sample of rock (say, in an asteroid) solidified right after the solar system formed. Then approximately what fraction of the radioactive element should be left in the rock today? Show your calculations
.
Answer: (½)^9.2 = 0.0019 or 19% Page 3 of 4
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AST 101 Lesson 4 Homework
Work: 4.6 • 10^9years / 5 • 10^8years = 9.2
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