Astronomy 101 Final Exam Questions & Answers 2024/2025 (Grade A+)

Astronomy 101 Final Exam Questions & Answers 2024/2025 (Grade A+) Melanoheliophobia - ANSWER-An irrational fear of black holes What are the three main attributes of photons? - ANSWER-Frequency, Wavelength, Energy If a photon's frequency is increased by a factor of two, what happens to its wavelength? - ANSWER-Its wavelength decreases by a factor of two If a photon's wavelength is increased by a factor of two, what happens to its frequency? - ANSWER-Its frequency is decreased by a factor of two If a photon's wavelength is increased by a factor of two, what happens to its energy? - ANSWER-Its energy is decreased by a factor of two The regions of the electromagnetic spectrum in order of increasing energy - ANSWER-Radio, infrared, visible, ultraviolet, x-rays, gamma rays What is incandescence? - ANSWER-The emission of electromagnetic radiation from a hot body as a result of its temperature. What is luminescence? - ANSWER-The emission of light by a substance that has not been heated, as in fluorescence and phosphorescence. What is the Doppler effect? - ANSWER-The Doppler effect occurs when a source of sound or light is moving relative to someone observing it If a light source moves toward you, what would you observe? - ANSWER-You would observe blue-shifted light You observe that light from a star has a longer wavelength than expected. What is a possible explanation? - ANSWER-The star may be moving away from you What effect does gravity have on light? - ANSWER-Gravity bends the path that light follows Two stars are near each other, and experience gravitational force between them. What happens if the distance between them is decreased by a factor of two? - ANSWER-The gravitational force increases by a factor of four Two stars are near each other, and experience gravitational force between them. What happens if the mass of one star is increased by a factor of two? - ANSWER-The gravitational force increases by a factor of two Two stars are near each other, and experience gravitational force between them. What does Newton's third law say about them? - ANSWER-The stars each experience the same force, but in opposite directions What is weight? - ANSWER-Weight is the apparent force due to gravity as something is pulled against a planet's surface If a thing is initially at rest, what happens to its kinetic energy as it is gravitationally pulled toward a massive object - ANSWER-Its gravitational potential energy is changed into kinetic energy When does an object have "escape velocity"? - ANSWER-Escape velocity is when an object has enough kinetic energy to escape a gravitational field What is a dark star? - ANSWER-A dark star has a surface escape velocity equal to the speed of light What is the relationship between a dark star and a black hole? - ANSWER-A dark star with a stable surface does not exist in nature, while a black hole with an event horizon at the same place as the dark star's surface exists and can be observed. What phenomena might black holes help explain? - ANSWER-Dark matter, dark energy What is the event horizon of a black hole? - ANSWER-The event horizon is the radius within which light cannot escape a black hole What is a star? - ANSWER-A star is a self-gravitating body of gas which is massive enough to sustain fusion What is hydrostatic equilibrium in a star? - ANSWER-Hydrostatic equilibrium is when gas pressure balances gravity What is luminosity? - ANSWER-Luminosity is a measure of the light emitted by a star What is apparent brightness? - ANSWER-The observed brightness of a star What is the phenomenon where stars produce light based on their heat? - ANSWER-Blackbody radiation What are differences between fusion and fission? - ANSWER-Fission is when a nucleus is split, and fusion is when nuclei merge What is one direct piece of evidence for fusion in the Sun? - ANSWER-The streams of neutrinos flowing outwards from the Sun's core Where does the energy from fusion come from? - ANSWER-The energy from fusion is created by the conversion of mass to energy through the equation E=mc^2 Which term describes the situation when an element is unable to release energy through either fission or fusion? - ANSWER-The iron catastrophe Identify the three methods of energy transfer. - ANSWER-Convection, conduction, radiation Name the regions of the sun in their order from inward to outward. - ANSWER-Thermonuclear core, convective zone, photosphere, chromosphere, corona If you see the spectrum of a distant star and it appears as a rainbow of colours with missing, dark lines, what could that mean? - ANSWER-There is an element in the photosphere of the star, which absorbs light with the same colours as the missing lines What causes main sequence turnoff? - ANSWER-A star runs out of hydrogen fuel and its core contracts while its outer envelope expands What happens when a star collapses to the point that its core is composed of iron? - ANSWER-The star can no longer get energy from fusion, and will die Which is a technique for finding the age of a cluster of stars? - ANSWER-Map the cluster on a Hertzsprung-Russell diagram and see what types of stars have disappeared from the main sequence How old is the Sun? - ANSWER-5 billion years old Put the steps of the Sun's evolution in chronological order from 1 to 3 - ANSWER-1) fuse hydrogen into helium at its core 2) run out of hydrogen and become a red giant 3) shed outer layers in a nebula and become a white dwarf What stops a white dwarf from collapsing? - ANSWER-Electrons in the core producing degeneracy pressure that stops the white dwarf from collapsing What causes a white dwarf to collapse, releasing the energy to explode in a Type Ia supernova? - ANSWER- What causes a core-collapse supernova? - ANSWER-A core-collapse supernova is caused by the collapse of a star with a high enough mass that it forms an iron core What can be produced when a high-mass star dies by core-collapse supernova? - ANSWER-A black hole, A neutron star, A nebula What is degeneracy pressure? - ANSWER-Degeneracy pressure is the resistance of certain particles to being in the same place and energy state what are characteristic of neutron stars? - ANSWER-1) Supported by degeneracy pressure 2) Primarily comprised of densely packed neutrons 3) Formed by core-collapse supernova Who discovered pulsars - ANSWER-Jocelyn Bell Burnell Who discovered that mass and energy are interchangeable? - ANSWER-Einstein who discovered the mass limit for white dwarfs? - ANSWER-Chandrasekhar who discovered evidence for dark matter? - ANSWER-Zwicky Who hypothesized the existence of dark stars? - ANSWER-Zwicky Who discovered the law of gravitation? - ANSWER-Issac Newton What is a main outcome of the Theory of Relativity? - ANSWER-Observers moving at different velocities do not agree on measurements of distance and time intervals. How are plots of paths in spacetime usually drawn by scholars of relativity? - ANSWER-Time is drawn on one axis, one spatial dimension on another, and one or more spatial dimensions are omitted. What is the "light cone" in relativity? - ANSWER-The light cone contains the events that can be experienced in 4-dimensional spacetime by an observer who travels slower than light. How can the Twin Paradox be resolved using Special Relativity? - ANSWER-Special relativity not only involves time dilation, but also length contraction. As a result, a person moving with respect to stars and planets measures their distance differently from a stationary person. In the twin paradox involving Luke and Leia, what happens to their age difference as Leia travels faster, assuming Luke stays still? - ANSWER-Luke and Leia end up further apart in age. Continues...