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60 Cards in this Set
- Front
- Back
Big Bang
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about 14 billion years ago, all matter
and energy in the universe was confined to an extremely small area, which suddenly exploded. The universe has been expanding in size ever since. The age of the Universe has recently been more accurately determined to be 13.7 ± .1 billion years. |
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Helium
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In the first few seconds of the universe, energy in the form of photons, condensed
out to form the matter of the universe. After a few minutes, the density and temperature of the universe was such that it fused some of the Hydrogen into Helium (about 25% by mass). |
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Milky Way
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the home galaxy of our Solar System, and of Earth.
it is 100,000 light years in diameter and 1000 light years in thickness |
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Early Astronomy
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Celestial bodies - the Sun, Moon, planets, and stars -
have provided us a reference for measuring the passage of time throughout our existence. Ancient civilizations relied upon the apparent motion of these bodies through the sky to determine seasons, months, years, and the hour of day. |
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First Calenders
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The earliest Egyptian calendar was based on the moon's cycles, but later the Egyptians
realized that the "Dog Star" in Canis Major, Sirius, rose next to the sun every 365 days, about when the annual inundation of the Nile began. Based on this knowledge, they devised a 365-day calendar that seems to have begun in 4236 BC. The Mayans of Central America relied not only on the Sun and Moon, but also the planet Venus, to establish 260 day and 365 day calendars. |
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Obelisk
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(slender, tapering, four-sided monuments) were built as early as
3500 BC. Their moving shadows formed a kind of sundial, enabling people to partition the day into morning and afternoon. Obelisks could also show the year's longest and shortest days when the shadow at noon was the shortest or longest of the year. |
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Shadow Clock
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came into use around 1500 B.C. to
measure the passage of hours. This device divided a sunlit day into 10 parts plus two twilight hours in the morning and evening. When the long stem with 5 variably spaced marks was oriented east and west in the morning, an elevated crossbar on the east end cast a moving shadow over the marks. At noon, the device was turned around to measure the afternoon hours. |
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Stonehenge
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built over 4000 years ago in England, but
its alignments show its purposes apparently included the determination of seasonal or celestial events, such as lunar eclipses, solstices and so on. |
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Zenith
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location in the sky, directly overhead
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Meridian
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imaginary line across the sky, connecting the north celestial pole,
the zenith, and continuing on to the horizon, due south. It splits the sky into an eastern half and a western half. At local solar noon, the Sun transits your meridian. |
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North and South Celestial Pole
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where the axis of Earth’s rotation meets its surface
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Celestial Equator
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a line around the Earth, 90 degrees from both poles. The largest circle of rotation of the
Earth. |
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Ecliptic
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defines the path of the Sun among the stars on the Celestial Sphere. It is tilted,
quite naturally, 23.5 degrees compared to the Earth's Celestial Equator Also defines your Zodiac sign |
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Asterism
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A grouping of stars, like the Big Dipper, that is not
officially a constellation |
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Circumpolar Stars
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a star that, as viewed from a given latitude on Earth, never sets (that is, never disappears below the horizon), due to its proximity to one of the celestial poles.
are therefore visible (from said location) for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare |
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Cause of Seasons
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when the Sun lies in the direction of the Summer Solstice, rotation of the
earth will not make the Sun set in the North Pole! Likewise, from the North Pole, when the Sun is at the Winter Solstice, the Sun will always be below the horizon. When the Sun is at either of the Equinoxes, The Sun stays right on the horizon. With a little bit of thought, you can imagine how this affects our view of the Sun from Cincinnati: at Summer Solstice, the Sun is much higher in the sky during the day and also stays above the horizon longer. |
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Equinox
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The point(s) on the Celestial Sphere where the Ecliptic and the Earth's Celestial
Equator cross |
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Solstice
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where the Ecliptic and Celestial Equator are farthest apart, making a Winter
and Summer solstice. |
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Solar Eclipse
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When the Moon casts its shadow on the Earth, this occurs.
During a solar eclipse the conical shaped shadow of the moon reaches back toward the earth and barely reaches to the earth. There are some eclipses where the shadow actually falls short. In either case, the size of the affected area on the earth directly under the moon's shadow is relatively small. The maximum size of the moon's shadow on the earth is about 167 miles in diameter and it travels at a minimum of 1,100 miles per hour. The shadow is typically smaller and usually moves faster than that. It is only inside of this racing shadow that you will experience a total solar eclipse as the moon's disk completely covers the sun's disk. Total solar eclipses are notoriously short, only a few minutes long. |
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Lunar Eclipse
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When the Earth casts its shadow on the Moon, this occurs
During a lunar eclipse, the moon, on its orbit passes through the shadow of the earth. Since the earth is so much larger than the moon, the earth's shadow is larger and longer. It is more than a million miles long, and, at the distance of the moon, is several times larger than the moon. Unlike a solar eclipse where the small shadow passes over your location in just a few moments, it can take the moon several hours to pass through the shadow of the earth. Lunar eclipses are much longer than solar eclipses. |
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Umbra
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The region of the
shadow inside of which totality is experienced is called the umbra. No part of the sun is visible from within the umbra. The umbra is cone-shaped and projects directly away from the sun diminishing in diameter as you move away from the shadow casting body. |
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Penumbra
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Around the umbra and antumbra is a region where the body only partially obscures the sun,
this region is called the penumbra and like the antumbra it is an expanding cone, but it originates from the body itself. |
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Antrumbra
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If you proceed past the tip of the umbrayou will enter another cone, this one increasing in diameter with distance, called the antumbra.
From within the antumbra, you would see the sun as a round disk larger than the body casting the shadow. |
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Total Solar Eclipse
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The umbra's footprint on the earth is very small and one must be directly under the
shadow to experience a total solar eclipse. |
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Partial Solar Eclipse
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If you are within several hundred miles of the path of the
shadow you will experience a partial solar eclipse as from your point of view, the moon's disk grazes past the sun only partially covering it. |
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Annular Solar Eclipse
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f the moon is near apogee, its distance from the earth
will be farther than the length of the umbra, so the antumbra moves across the earth's surface. From within the antumbra the disk of the moon is smaller than the disk of the sun and it cannot cover it completely. It leaves the disk of the sun as a ring around the smaller disk of the moon. This is called an annular solar eclipse derived from the Greek word annulus, meaning ring or circle. |
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Photosphere
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Surface of the sun
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Chromosphere
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a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep.
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Corona
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Extended outer atmosphere of the sun
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Eclipse Year
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The nodes of the lunar orbit are gradually shifting their orientation in
space, giving us proper alignment about every 346.6 days |
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Ofteness of Eclipses
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Since the eclipse year is shorter than the tropical year, it is possible to have the tropical year begin
with an eclipse season, experience a second eclipse season about 155 days later, and end the year with part of a third eclipse season. This only happens once every couple of decades and provides the opportunity for as many as 7 eclipses in 1 tropical year. Typically there are two eclipse seasons per tropical year and typically each eclipse season contains two eclipses. So usually there are only 4 eclipses a year, 2 solar and 2 lunar, but precise phasing of the tropical year, the eclipse year and the moon's nodes, 5 or 6 or (very rarely) 7 eclipses can occur in 1 tropical year |
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Nodes
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the two points where the Moon's orbit intersects the plane of the Earth's orbit, the
ecliptic |
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Why does the moon turn red during a lunar eclipse
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Some of the Sun's light passes through Earth's
atmosphere and is bent around and behind the Earth. Much of this light is scattered as blue light, and never reaches the lunar surface. Only the longer wavelengths of light (mostly red or orange) will reach the Moon, tinting its surface in a coppery glow. |
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Penumbral Lunar Eclipse
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Sometimes the moon only enters the penumbra without
touching the umbra. |
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arc second
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: a sub-division of an arc-minute (1/21,600th of a circle) into 60 equal finer divisions. Equal to 1/60th of an arc-minute, 1/3,600th of a degree, or 1/1,296,000th of a complete circle. It is symbolized by a double accent or quote following the value, as in 8” (eight seconds). It is an angular measurement and not related to any unit of time.
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arc minute
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a sub-division of a degree (1/360th of a circle) into 60 equal finer divisions. Equal to 1/60th of a degree, or 1/21,600th of a complete circle. It is symbolized by a single accent or quote following the value, as in 31’ (thirty-one minutes). It is an angular measurement and not related to any unit of time.
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angular size of the moon
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29.3′ to 34.1′
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Why were Aristotle's astronomical theories so detrimental to the progress of
western astronomy? |
His
astronomical views were biased towards absolute symmetry, simplicity and perfection. Aristotle, proposed models where the stars, Sun, Moon, and planets are attached to spherical transparent shells undergoing uniform circular motion around the Earth. This is known as a Geocentric Universe. |
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Parallex
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Stellar parallax occurs as the Earth orbits the Sun and our line of sight to a nearby
star varies. The effect is to make the star appear to shift position over the course of the year. In reality, stellar distances are so great that parallax shifts are less than an arc second, completely unobservable to the unaided eye. |
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Parallex continued
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1. The Earth is not part of the heavens.
2. The celestial objects are bright points of light while the Earth is an immense non-luminous sphere of mud and rock. 3. There is little change in the heavens: Stars are the same night after night. Earth is home of birth, change, and destruction. Celestial bodies have immutable regularity that is never to be achieved on the corruptible Earth. 4. Our senses show Earth is stationary: Air, clouds, birds, and other things unattached to Earth are not left behind, as they would be if the Earth were moving. There is no strong wind. If the Earth were moving, then a man jumping from a high point would hit the Earth far behind from the point where the le |
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Heliocentric
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Sun centered Universe
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Ptolemaic model for Planetary Motions
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Ptolemy attempted to explain the backwards motion in the sky by placing the planets on a small circular path that was not quite centered on a larger circular path. Offset circles on circles:
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Epicycles
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A small circle whose center moves around the circumference of a larger one.
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retrograde motion
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The motion in question is called retrograde motion and it occurs when a particular planet, "wandering" eastward along the ecliptic for the most part, slows down, stops and then moves westward for a while. It soon (several weeks later) slows down, stops moving westward, and begins moving eastward again.
-This temporary, apparent, "backwards" motion against the Celestial Sphere is caused by the Earth orbiting the Sun faster than the planets that are farther from the Sun. -all the planets farther away from the earth have retrograde motion. They are called superior planets. |
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After the fall of the roman empire
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IX-XI century A.D. Intensive development of Arabic and Persian astronomy (star
charts and catalogs, planets and the Moon movement, better estimations of the Earth size, and calendar improvement) A.D. 813 Al Mamon founds the Baghdad school of astronomy. Mathematike Syntaxis by Ptolemy is translated into Arabic as al-Majisti (Great Work) later called by Latin scholars Almagest A.D. 903 Al-Sufi draws up his star catalog 1054 Chinese astronomers observe supernova in Taurus (now this supernova remnant is known as the Crab Nebula (M1) |
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Why did Copernicus's heliocentric model 'fail'? What is the significance of
'The Revolution'? |
Recall the premise for the Ptolemaic Model: 1) Earth-Centered, 2) Uniform
circular motion. BOTH are wrong and the Copernican model only corrected the first error. In this way, the Copernican model had both radical and conservative aspects By the 15th century exploration of new trade routes via sea-going ships begins in earnest. New navigation technologies are needed (based on astronomical knowledge). The Catholic Church's power begins to erode. People begin asking for a new way of worship. The Protestant Reformation! |
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Brahe
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Danish, From his underground observatory, Uraniborg, he studied and measured the heavens for more than 20 years. He compiled detailed observation logs of the locations of the stars, planets and comets, all before the invention of the telescope. He never processed any of the data and hired Johannes Kepler to analyze the data and provea Brahe-based Ptolemaic hybrid model of the Universe correct a year before Brahe’s death
He believed in a geocentric universe He discovered a new distant star in Cassiopeia |
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Kepler
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Used Copernicus observations and Brahes data to develop his three laws
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Keplers three laws
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1. The orbit of every planet is an ellipse with the Sun at one of the two foci
2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.[1] 3. The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. -third equation uses p as orbital period, a as the semi major axis in oribt, m as mass and g as gravitational constant. I think Galileo would later know why these laws existed. |
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Galileo FIVE observational discoveries
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1. Craters on the Moon
2. The milky way was made of stars 3. Moons of Jupiter 4.Sunspots 5.The phases of Venus |
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Craters on the Moon
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He reported that the moon was not perfect, but instead
had deep shadows from valleys and mountains on its surface. He also showed it was a world not unlike Earth. |
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The milky way was made of stars
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He showed that the great "cloud" called the
Milky Way (which we now know to be the disk of our spiral galaxy) was composed of enormous numbers of stars that had not been seen before. |
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Moons of Jupiter
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Galileo observed 4 points of light that changed their positions with time around the
planet Jupiter. He concluded that these were objects in orbit around Jupiter. Io, Europa, Ganymede, and Callisto are shown below with approximately the correct scale of their orbit and motion to the size of Jupiter's disk. These observations showed there were new things in the heavens that Aristotle and Ptolemy had known nothing about. Jupiter's moons demonstrated that a planet could have moons circling it (other centers of motion) that would not be left behind as the planet moved around its orbit! |
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Sunspots
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Galileo saw that the Sun had dark patches on it,
sunspots. Furthermore, he observed motion of the sunspots indicating that the Sun was rotating. "Blemishes" on the Sun were contrary to the doctrine of an unchanging perfect substance in the heavens, and the rotation of the Sun made it less strange that the Earth might rotate on an axis too, as required in the Copernican model. |
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The phases of Venus
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Galileo used his telescope to show that Venus went through a complete set of
phases, just like the Moon. This observation was among the most important in human history, for it provided the first conclusive observational proof that was consistent with the Copernican system but not the Ptolemaic system. This was because the two systems make different predictions for the progression of the phases of Venus (see below) These discoveries were made from 1608 to 1612, making him quite famous AND at the center of controversy with the Catholic Church. By 1616, Galileo was formally requested by the Church to cease debating (teaching or publishing) his scientific results that supported the Copernican model. From 1616 until around 1630, Galileo did hold off from working on Astronomy. However, he returned to his astronomical research later in life, which eventually got him into deep trouble with the Inquisition. At age 70, he was forced to recant the Copernican system and spent the rest of his natural life under house arrest at his villa. |
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Newton discoveries
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Newton invented calculus and designed the first reflecting telescope (called a
Newtonian design!) based on his studies of light. For the purposes of this class, we shall limit ourselves to his discoveries in Mechanics, specifically having to do with motion and gravitation. In particular, Newton thought like no one previous to him: Analytically seeing the Universe's motions and recognizing that there existed a force, a natural influence existing between particles that affected these motions. |
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Newtons THREE laws
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I. Every object in a state of uniform motion tends to remain in that state of
motion unless an external force is applied to it. II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. In this law the direction of the force is the same as the direction of the acceleration III. For every action there is an equal and opposite reaction. |
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Bodes Law
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The law relates the mean
distances of the planets from the sun to a simple mathematic progression of numbers. Doesnt work for all planets I think Newton is science not Bode |
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Clavius
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German, Jesuit Vatican astronomer to Pope Gregory XIII, who calculated a more correct value for the length of the tropical year. He provided the leap year cycle pattern to keep the civil year (integer solar days) and the tropical (seasonal) year in synch, what we call today the Gregorian Calendar. Wednesday October 4 1582 was followed by Thursday October 15 1582 to account for the extra days that had been added in since Julius Caesar introduced the simple 4-year pattern of leap years 1600 years earlier. Also created decimal and vernier scale
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Harrison
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Carpenter, clockmaker and inventor of the Marine Chronometer and solver of the "Longitude Problem". He is responsible for modern accurate timekeeping and made it possible for ships to accurately calculate their positions on the open sea. He is credited with inventing jewel bearings, roller bearings, bi-metallic strips for temperature compensation, the grasshopper escapement and the gridiron pendulum.
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