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80 Cards in this Set
- Front
- Back
How old is the Universe? |
Around 14 Billion years old |
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Scientific Method 3 Parts |
1. Theory 2. Prediction 3. Experiment |
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True or False, the science can START OR END at any point of the scientific method? |
True |
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True or false, science proves things? |
False |
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Science proves theories, true/false |
false, science disproves theories it rejects bad ideas and theories science is concerned with what is useful |
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Modern Scientific Theories 4 parts |
1. Requirement: Testable/Falsifaible 2. Requirement: Repeatable/Repeated 3. Refinement: Simple 4. Aesthetics: Elegant |
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What is testable/falsifiable? |
the inherent possibility thta it can be proved false.
Theory must make predictions about phenomena such that failure to confrim predictions results in rejection of theory |
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What is repeatable? |
Anyone an repeat and prove to themsleves that the results of the experiment are intially found |
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What is a simple theory? |
Two competing theories; the simpler one is preferred Both explain the same phenomena Generally interpreted to mean: a theory should not include unecessary/extra/superflous details |
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What is elegant theory? |
Theory can be stated concisely, but consequences are broad Ties together multiple phenomena in a way that is simpler than their independent theories |
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Were Ancient Astronomers were scientists? |
Yes, they observed the night sky, theorized patterns and made predictions...many ancient theories now disproved but does'nt mean that it wasn't science of the time |
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What is a constellation? |
Patterns observable in the proximity of bright stars to each other |
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Zodiac constellations |
Line from Earth to sun points to zodiac constellation Therefore the sun blocks the astrological constellation |
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What is Asterism? |
Big Dipper, Great Bear etc. A collection/pattern of start that is not a constellation |
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Usefulness of ancient astronomy (3)
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1. Travel: North Star/Polaris stays in the same position 2. Agriculture: Constellation position indicated seasons 3. Behaviour: Constellation overhead during day of birth indicates aspects of a person's future |
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Celestial Sphere |
The seeminlgy static angular relations between stars that cylce across the sky during a year or put another way... An imaginary sphere of gigantic radius with the earth located at its center. The poles of celestial sphere are aligned with the poles of the Earth. The celestrial equator lies along the celestial sphere in the same plane that includes the Earth's equator. |
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Celestial Poles |
The distant point in the night sky that ll stars rotate about - example Polaris the North Star |
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Precession |
Like a spinning top, the axis of rotation oscillates...so polaris is the north start but Thuban was the North Star in 3000 BC |
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CCelestial Equator |
The imaginary line that is equidistant from each of the celestial p[oles...coincides with the Earths equator |
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Declination and Right Ascension |
We can locate any object on the celestial sphere by giving two coordinates, called the Right Ascension and Declination. Celestial coordinates. Stars and galaxies have almost fixed positions in right ascension and declination...planets and sun on other hand move around Reference point is the vernal equinox |
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Ecliptic |
Because of the Earth's yearly orbital motion, the sun appears to circle the ecliptic.... Ecliptic is the path that the sun appears to trace among the stars in a year because of the Earths revolution around it. |
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Solstice |
When the sun is at the furthest point from the equator
Winter solstice in December and summer solstice in June |
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Equinox |
When the sun is directly overhead of equator Vernal Equinox in March Autumnal Equinox in September |
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What causes the seasons? |
The earth's tilt! the earth is closest to the sun during North Hemisphere winter! |
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Solar Day |
Time taken for the sun to be in the same position overhead 24 hours ...1 hour = 60 mins...1 min = 60 seconds |
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Sidereal Day |
Time taken for the stars to be in the same position overhead 23 hours 56 minutes |
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Triangulation |
The over-arching principle of using triangles to measure determine distances Measure 1 (or two angles) and 1 distance Planet distance determined from two observations Star distance determiend from orbit around sun Reverse process to measure diameter size of planet! |
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Eratosthenes Measurement |
Measured parallax between 2 cities 780km apart Used deep well to measure angle, found 7.2 degrees Calculated radius of 6366km...actual was 6378km |
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Measuring things withon our solar system |
Use two distant observations ot measure angles |
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Measuring things outside our solar system |
Mearure angles now and 6 months from now |
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AU |
Astronomical Unit The average distance between Earth and Sun 1 parasec = 206 265 AU =30860000000000km On a 1m radius circle, 1" would cover about 5 um of the circumference |
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Ancient Astronomy |
Purpose 1: Predict seasonal changes Purpose 2: Assist travelers Knowledge was guarded closely Visual observations enhanced with ancient tools/devices Guard knowledge by obscuring with myth, ritual |
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Stonehenge |
3D calendar, tracked celestial events |
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Ancient Chinese Astronomy |
Created detailed star maps Used as calendar, aslo prophetic regarding dynasties Observed "guest stars such as SN 1054 |
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Islamic Astronomy |
During Europe's Dark Ages, Islamic Astronomers improved upon Ancient Greek astronomy Zenith, Azimuth, Altitude |
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Zenith |
the direction directly overhead |
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Azimuth |
The angle relative to North Direction |
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Altitutde |
The angle relative to the horizon |
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Geocentric Universe |
Ancient Greeks distinguished between Sun/Moon and the Stars
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What is the celestial dome? |
a sphere that covered the sky at night which carried the stars |
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Geocentric Universe |
"Earth centred" all planets, stars, etc orbit the Earth |
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Path of Planets |
Planets speed up and slow down and even reverse |
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Prograde |
When planets move in the same direction as the stars |
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Retrograde |
When the planets move in opposite direction of the stars |
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Geocentric Theory (4) |
Needs to account for: 1. Motion of the stars 2. Motion of Sun and Moon 3. Brightness changes due to distance from Earth 4. Retrograde/prograde motion of planets |
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Geocentric theory - epicycle |
a small circle whose center moves around the circumference of a larger one |
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Geocentric theory - planets travel along an epicycle |
True |
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T/F planets travel along the epicycle, the centre of which orbits the Earth along a deferent |
True |
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How do geocentric models predict the future positions of planets? |
By adjusting the size of deferent, epicycle and the speed of each |
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Improvements of Geocentric theory (2) |
Centre of deferents were offset from the Earth (no longer truly geocentric) Deferents of inferior planets had to be tied to the Sun |
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Ptolemaic Model |
Required 80 distinct circles |
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Heliocentric Model |
More elegant theory than Geocentric and Plotemaic |
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who rediscovered Aristarchus' Greek theory of heliocentricity - sun centred |
Copernicus |
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What was the Copernican Revolution |
the heliocentric model |
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Foundations of Coperniacan Revolution (7) |
1. Celestial spheres did not have single common centre 2. Earth is the centre of gravity and the centre of Moon's orbit 3. All other planets revolve around the sun 4. The stars (firmament) are much much further away from Earth than the Sun 5. The motion of the stars id due to the motion of the Earth (about its own axis) and stars are otherwise "fixed in place 6. The motion of the Sun during the day is also due to the rotation of the Earth 7. Retrograde motion is also due ot the motion of the Earth |
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True or false - Planets orbit retrograde orbit in our solar system |
False, no planet in our solar system orbits retrograde |
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True or flase Venus and Uranus rotate in retrograde? |
True, they rotate in retrograde |
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Inferior Planets |
Orbit is closer to the Sun than Earth |
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Superior planets |
Orbit is further from Sun |
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Conjunction |
When the planets are close to the axis between Earth and the Sun |
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Opposition |
When superior planets are opposite Earth in line with the Sun |
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What were Galileo's Methods (2) |
1. Performed experiemtns to test predictions 2. Used a telescope which he built himself |
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What did Galileo discover? |
1. Discovered/observbed that the moon had mountains, vallyes and craters 2. Observed sun spots (sun rotated!) |
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Galileo and Jupiter |
Observed 4 small points of light near Jupiter which were:
1. always in proximity to Jupiter 2. Smaller than jupiter 3. moved back and forth across jupiter |
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Galileo's explanation of the light near jupiter explained... |
four moons of Jupiter...clear evidence of an object NOT orbiting the earth |
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Galielo and Venus |
Observed Venus and discoverd Venus orbiting the Sun, not an epicycle of a deferent |
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James Bradley |
Observed 20" aberration of starlight (stellar parallax) in 1728 |
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Geocentricity was rejected when James Bradley observed aberration of starlight (stellar parallax) |
False, Took until 1838 for conclusive measurements of stellar parallax to completlely reject geocentricity |
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Stellar parallax |
the apparent shift of postion of any nearby star against the backdrop of distant objects |
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Tycho Brache |
Used naked eye measurements which were acccutrate toe date to 1'
Stars, planets, coments, SN |
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Keplers Triangulation technique (3) |
1. Motion of the Earth to generate baseline distance 2. Referenced all measuremnts to R*earth (not known in kilometres, just an arbitrary unit, AU 3. Knowledge of the angle that Earth moved in 1 day (1/365 of a circle, close to 1 degree) |
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Laws of Planetary Motion (3) |
1. Orbits are not Elliptical (not circular), with the Sun at one focus 2. Equal areas of the ellipse are swept out by a line connecting Sun Sun to the planet in equal intervals of time ✤3) The SQUARE of a planets orbital period is equal to the CUBE of its semimajor axis |
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✤Laws of Planetary Motion(3) |
1) Orbits are ELLIPTICAL (not circular), with the Sun at one focus 2) Equal areas of the ellipse are swept out by a line connecting Sun to the planet in equal intervals of time 3) The SQUARE of a planets orbital period is equal to the CUBE of its semimajor axis |
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True/ False: Elongation IS NOT described by the eccentricity |
False, Elongation IS described by the eccentricity |
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T/F Sun sits at one point of the foci |
True |
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Perihelion |
Closest approach |
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Apheilioin |
Furthest approach |
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Netwons Laws (3) |
1. Everything in motion, or at rest, continues on in that state until acted upon by an external force. 2. An unbalanced force leads to an acceleration 3. For every action (i.e. Force), there is an equal and opposite REaction. |
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T/F Aristotle said “natural state of all things is at rest” |
True |
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Newton's Law of Gravitation |
a) “Any object with mass exerts a gravitational force on all other objects” ✤b) Gravitational forces are ALWAYS attractive c) The Earth has a large mass, and exerts a force on all objects on its surface |