History of Astronomy – Flashcards
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What is refraction? What did Galileo's refracting telescope consist of? What does the primary lens do? What does the eyepiece do?
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Refraction is the bending of light rays as they pass from one medium to another (air to glass). Galileo's refracting telescope consists of primary lens. The primary lens sends more light to eye would receive on its own. The eyepiece re-focuses the rays for the eye
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What change did Kepler make to the refracting telescope, and why?
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Kepler used convex lens at eyepiece instead of concave
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What did Galileo prove about falling objects? Who did this contradict, and why?
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Galileo proved all objects of different mass fall at the same rate. It contradicted Aristotle idea that heavier objects fell faster
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Even before he looked through a telescope, which planetary model did Galileo privately support? How do we know this?
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Galileo privately supported heliocentrism. Galileo admitted in letters to Kepler but would not support it publicly.
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What did Galileo see when he observed the Moon with the telescope? How did this contradict Aristotle's teachings about the celestial bodies?
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Galileo saw the surface of the moon revealed that celestial bodies are not perfect unblemished spheres (rough, uneven). Aristotle said that everything in heavens was perfect and spherical.
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What did Galileo discover when he observed the Milky Way with the telescope? How did this contradict Aristotle's explanation for the Milky Way?
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Galileo discovered that the Milky Way is not atmospheric (as Aristotle taught), but the combined light from millions of stars
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As a result of Galileo's book, what was he charged with by the Roman Inquisition in 1633, and what was his sentence?
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Galileo was sentenced to house arrest for life and publicly deny heliocentrism as heresy. His books were banned
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What did Galileo believe to be the cause of Earth's high and low tides? Why did he include this theory in his book?
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That Earth's ocean tides are proof of Earth's motion. He included this theory in his book because Pope previously rejected he included this theory in his book cuz he thought that it *proved* that Earth moves.(but he was wrong)
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What did Galileo publish in the 1630s, and with whose permission? Describe the format of the book and its characters. Why did this book antagonize the Pope?
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Galileo published "Dialogue on the Two Great World Systems"-1632. Fictional debate between Aristotelian, Copernican and Referee. Aristotelian was portrayed as a fool who spoke the pope's words while Copernican was wise and witty
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When Galileo heard that he was being demonized by the Catholic Church, what did he do in 1615? What were the consequences of his action
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Galileo circulated a letter that he wrote to his employer's wife (the grand duchess of tuscany)... the letter defended the Copernican model. and as a result, the church reviewed the evidence for the Copernican model and decided that it was heresy to believe that the Earth moves, so they banned Copernicus' book, and Keplers' and placed a ban on Galileo, that he musn't "hold or defent" copernicanism
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Why did the Roman Catholic Church maintain that the Universe is geocentric?
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Roman Catholic Church maintained that the universe is geocentric due to Scripture-bible
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What happens to sunspots when they near the edge of the Sun's surface? What did this convince Galileo about sunspots? Why did his conclusion contradict Aristotle?
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Sunspots are blemishes on the sun's rotating surface-imperfection in celestial bodies sunspots appear compressed, or squished together, as they near the edge of the sun, this convinced Galileo that they are actually on the surface of the sun, which contradicted Aristotle, who taught that the Sun is perfect and therefore can't have blemishes on it.
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What did Galileo see when he observed Saturn with the telescope? Why did this contradict Aristotle? What causes this planetary phenomenon to occasionally disappear?
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A). Galileo saw appendages on either side of Saturn he thought they were bumps of some sort attached to the sides of the planet, like ears. B). this contracted Aristotle, who taught that the planets are all perfect spheres C). Disappearance of Saturn's rings is due to our changing view of their tilt
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Why did Galileo not observe phase changes in the outer planets?
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He couldn't observe phases in outer planets since only full and gibbous phases are possible -outer planets are never between Earth and sun.
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What is Venus' phase when it appears smallest, and why? What about when Venus appears biggest?
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Venus is full, as it appears smaller in size. When it is thin crescent it appears big.
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What did Galileo observe with the telescope when he compared the appearance of planets to stars? How did this support the Copernican argument that the stars are too distant for their parallax to be seen?
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he found that planets taken on a circular (or disky) shape, while stars remain looking like pin- points of lite. this can be explained if stars are much further away than planets, which supports Copernicus' argument that the stars are too distant for parallax to be seen
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Which is longer Earth's sidereal day or solar day?
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Solar
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Longitude on the Earthly coordinate system when projected on the sky is
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right ascension
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Within how many degrees of the ecliptic do all the naked eye visible planets move?
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7
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Precession causes the Sun's vernal equinox point to do what over time?
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shift westward
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At what angle is the ecliptic tilted relative to the celestial equator? (in degrees)
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23.5
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What line does the Sun cross at noon?
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meridian
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How many times a year can an eclipse happen?
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2
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The moon's sidereal period is
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27.3
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Which planet will never be seen at midnight?
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Mercury
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How many degrees does the moon move against the background stars in one day?
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13
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What event does the tomb at new grange orient on?
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sunrise at winter solstice
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which two regions have been most intesviley investigated for their prehistoric astronomy?
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American tropics and Northwest europe
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where does the sun rise and asset almost vertically?
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in the tropics
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do the ceques and the naza lines of the inca orient solely on astronomical events?
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no
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people have speculated that the 56 aubrey holes could have been used to predict
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eclipse
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astronomy has been used for
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navigation, time keeping, predicting the future
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the mayans tended to orient buildings on the motion of which planet
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venus
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seen form earth the paths of the sun and moon and earth cross roughly every
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173 days
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no modern groups still use the sky to keep time and predict the seasons?
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yes
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what alters what stars can be seen from any given location over the centuries
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precession
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by how many days does the seasonal (solar) year exceed the lunar year?
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11
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what event in ancient egypt took place when the waters of the nile began to flood?
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helical rising of sirius
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decans in egypt were based on what?
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regular rising of 36 constellations
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a major problem with creating an accurate calendar is
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natural day, month, year lengths don't match
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what handicapped the development of Egyptians?
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lack of place value system of math
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until the 17th century the goal of astronomy was to
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predict motions in the sky with accuracy
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the babylonian calendar
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was lunar
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our use of 60 for the number of minutes in the hour comes from which culture
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babylonians
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what material did the babylonians record their observations on?
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clay
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19 solar years is how many lunar months
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235
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Egyptian obelisk
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Shadows tell time of day.The obelisk is phallic in its appearance. It is symbolic of the Egyptian sun god, Ra, and is an ancient symbol of male energy and generation (G) in Freemasonry.
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Stonehenge
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Constructed: 3000 - 1550 B.C. Alignments with locations of sunset, sunrise, moonset and moonrise at summer and winter solstices. Probably used as calendar.56 Aubrey holes could have been used to predict lunar eclipses
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Stonehenge has the major alignment to what astronomical event?
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Summersolstice
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Which star's helical rising marked the flooding of the Nile River?
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Sirius
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Constellations
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88 constellations fill the entire sky.12 constellations along the ecliptic. Zodiac, and technically 13
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the brightest stars in a constellation
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may actually be quite far away from each other
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Which one is a fainter star?
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Magnitude 23.5
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Atmosphere refracts starlight in random direction very quickly
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Stars twinkle • Planets don't
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Magnitude was introduced by
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Hipparchus 160- 127 B.C.):
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Zenith
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Point on the celestial sphere directly overhead
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Nadir
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Point on the c.s. directly underneath (not visible!)
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Celestial equator
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projection of Earth's equator onto the c. s.
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north celestial pole
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projection of Earth's north pole onto the c. s.
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What is Zenith?
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Point on the celestial sphere directly overhead
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What is celestial equator
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projection of the earths equator onto the c.s
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What is North Celestial Pole?
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projection of the earths north pole onto the c.s
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Earth rotates
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west to east,so stars appear to circle from east to west (daily).
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Earth orbits
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the Sun(revolves) once every year (annual), counter-clockwise as viewed from above the North Pole.
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The Sun's gravity on slanted Earth causes
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the axis of rotation to wobble around the vertical w.r.t. the Ecliptic plane. It takes about 26,000 years and is called precession (the precession of the Equinox).
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heat
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the closer you are the hotter it is
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in SUMMER
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the Sun is high in the sky, the amount of direct sunlight received is greater.
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in WINTER
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the Sun is low in the sky, the amount of direct sunlight received is less.
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seasons
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Earth's axis of rotation is inclined vs. the normal to its orbital plane by 23.5°
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AXIS TILT
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is the key to the seasons; without it, we would not have seasons on Earth.
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Summer solstice:
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Highest path, rise and set at most extreme north of due east.
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Winter solstice
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Lowest path, rise and set at most extreme south of due east.
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Equinoxes
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Sun rises precisely due east and sets precisely due west.
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what are Synodic and Sidereal period of the Moon?
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29.53 days, 27.32 days
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What is last quarter (3rd quarter) phase of the Moon and when can you see it?
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Opposite D shape, 90o in the west of the Sun, seen before sunrise
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What is first quarter phase of the Moon and when can you see it?
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D shape, 90o in the east of the Sun, seen after sunset.
