Astronomy Concepts: Seasons, Eclipses, Tides, Kepler's Laws, and Newton's Laws, Quizzes of Astronomy

Download Astronomy Concepts: Seasons, Eclipses, Tides, Kepler's Laws, and Newton's Laws and more Quizzes Astronomy in PDF only on Docsity! TERM 1 What causes seasons? DEFINITION 1 The Earth's tilt causes seasons. TERM 2 When do we have summer in the northern hemisphere? DEFINITION 2 We have summer in the northern hemisphere when the northern hemisphere is tilted toward the Sun. TERM 3 Why is it warmer in the summer than in the winter? DEFINITION 3 It is warmer in the summer than in the winter because the sunlight is more concentrated on the ground when the Sun is higher in the sky. TERM 4 When do the vernal and autumnal equinoxes occur? DEFINITION 4 When the declination of the Sun is zero degrees, or located on the celestial equator. TERM 5 What is the vernal equinox? DEFINITION 5 The first day of spring. TERM 6 What is the autumnal equinox? DEFINITION 6 The first day of fall. TERM 7 When do solar eclipses occur? DEFINITION 7 Solar eclipses occur when the Moon is between the Sun and the Earth. They occur at NEW MOON. TERM 8 When do lunar eclipses occur? DEFINITION 8 Lunar eclipses occur when Earth is between Sun and Moon. Lunar eclipses occur at FULL MOON. TERM 9 What causes tides? DEFINITION 9 Tides are caused by the difference between the Moon's gravitational force on different sides of the Earth. TERM 10 What is the time between high tides? DEFINITION 10 12 hours, 25 minutes TERM 21 When do retrograde motions occur naturally? DEFINITION 21 Retrograde motions occur naturally if planets further from the Sun move more slowly. For example, Earth and Mars. Earth's orbital radius is 1 AU and its orbital speed is 30 km/sec. Mars' orbital radius is 1.5 AU and its orbital speed is 24 km/sec. As Earth "laps" Mars, Mars appears to go backward as seen by an observer on Earth. This is the apparent retrograde motion. TERM 22 Why is Copernicus' model met with great resistance? DEFINITION 22 It implies that the distance from the Sun to the stars is much greater than the distance from the Sun to the Earth. TERM 23 What are the radical aspects of the Copernican model? DEFINITION 23 1) Earth is not at the center of the universe.2) Earth is moving.3) Earth is just another planet.4) Space is big-- really big. TERM 24 What are the conservative aspects of the Copernican model? DEFINITION 24 1) Uniform circular motion assumed2) Epicycles are still required TERM 25 Eclipse DEFINITION 25 An event in which one astronomical object causes a shadow on another or crosses our line of sight to the other object. TERM 26 Semimajor Axis DEFINITION 26 Halft the distance across the long axis of an ellipse; in this text, it is usually referred to as the average distance of an orbiting object, abbreviated in the formula for Kepler's third law. TERM 27 Eccentricity DEFINITION 27 A measure of how much an ellipse deviates from a perfect circle; defined as the center-to-focus distance divided by the length of the semimajor axis. TERM 28 Aphelion DEFINITION 28 The point at which an onject orbiting the Sun is farthest from the Sun. TERM 29 Periphelion DEFINITION 29 The point at which an object orbiting the Sun is closest to the Sun. TERM 30 Ellipse DEFINITION 30 An oval built around two points, called focuses (or foci) TERM 31 What is Kepler's first law of planetary motion? DEFINITION 31 Each planet moves in an ellipse with the Sun at one focus. TERM 32 What happens to the ellipse when the foci are close together? DEFINITION 32 The ellipse is nearly circular and the eccentricity is close to zero. TERM 33 What happens to the ellipse when the foci are far apart? DEFINITION 33 The ellipse is very flattened and the eccentricity is close to one. TERM 34 What is Kepler's second law of planetary motion? DEFINITION 34 The line between the Sun and the planet sweeps over equal areas in equal time intervals. TERM 35 What are the consequences of Kepler's second law? DEFINITION 35 Planets move fastest when closest to the Sun. TERM 46 What is Newton's First Law of Motion? DEFINITION 46 An object remains at rest, or moves in a straight line at constant speed, unless acted on by an outside force. What is TERM 47 What is Newton's Second Law of Motion? DEFINITION 47 The acceleration of an object is directly proportional to the force acting on it, and inversely proportional to its mass. In mathematical form: a = F/m or F = ma. Or alternatively, F = G(Mm/r^2) TERM 48 What is Newton's Third Law of Motion? DEFINITION 48 For every action, there is an equal and opposite reaction. Whenever A exerts a force on B, B exerts a force on A that's equal in size and opposite in direction. All forces come in pairs. TERM 49 What is Newton's Law of Gravity? DEFINITION 49 Gravity is an attractive force acting between all pairs of massive objects. Gravity depends on 1) masses of the two objects, and 2) distances between the objects. TERM 50 Gravitational force varies _____ with mass and _____ with square of distance. DEFINITION 50 directly; inversely TERM 51 What was Newton's assumption about the Moon's orbit? DEFINITION 51 He said that the Moon is on a circular orbit. Even if its orbit were perfectly circular, the Moon would still be accelerated. TERM 52 How did Newton expand Kepler's first law of motion? DEFINITION 52 While Kepler said that the orbits of the planets around the Sun are ellipses with the Sun at one focus, Newton said that the orbits of ANY PAIR OF OBJECTS are CONIC SECTIONS with the CENTER OF MASS at one focus. TERM 53 Light-year DEFINITION 53 (ly) The distance that light can travel in one year. 1 light year = 9.5 x 10^12 km. It's a unit of distance. TERM 54 Energy of a photon DEFINITION 54 The energy of a photon is related to the frequency of a wave. E = hf. E= energy of a photonf = frequency of lighth = Planck's constanth = 6.626 x 10^-34 joule x s TERM 55 What does a longer wavelength mean? DEFINITION 55 A lower frequency TERM 56 Light forms a spectrum from ______ to ______ wavelength DEFINITION 56 short to long TERM 57 What are the wavelengths of visible light? DEFINITION 57 400 to 100 nanometers TERM 58 What is the wavelength of blue light? DEFINITION 58 480 nm TERM 59 What is the wavelength of green light? DEFINITION 59 530 nm TERM 60 What is the wavelength of red light? DEFINITION 60 660 nm