Lesson 3 Flashcards
What is considered to be the oldest science?
Astronomy
What are the 7 days of the week named after?
Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn)
How did people in Central Africa in 6500 BC use the sky to predict the seasons?
Due to the orientation of the crescent moon
How did Greek philosophy spread?
Through Alexander the Great in (323 BC)
- his followers would found the library of Alexandria, the biggest site of ancient researchers
Who preserved Greek philosophy?
The Muslims in Baghdad
- the fall of Constantinople in 1453 caused Eastern scholars to head to Europe, helping to ignite the European renaissance
Where does the geocentric model place earth?
At the centre of the universe
What properties did Plato claim the heavenly bodies should have?
They should be perfect, and thus their orbits should be perfect circles
What did Ptolemy have to add to Plato’s model?
He explained retrograde motion, keeping a geocentrist view of the universe
What did Copernicus suggest? Was he the first to do this?
He suggested a sun-centred model (however, he kept the idea of perfect circles)
- no, he was not (Aristarchus of Samos was the first one to propose this)
What did Tycho Brahe contribute to our knowledge of astronomy?
He compiled the most accurate naked eye measurements, but he still could not observe stellar parallax
- he still thought earth was at the centre, but now suggested that other planets orbited the sun
What did Johannes Kepler contribute to the field of astronomy?
He tried to match Tycho’s observations with circular orbits but he found an 8 arcminute discrepancy which led him to conclude that orbits were not perfect circles but rather were elipses
What are foci?
Two points on either side of an elipse
What is the origin?
The centre of the elipse
What is the major axis?
It connects both foci
What is the semimajor axis?
The distance from the origin to one focus
What is the amount of squeezing of a circle referred to?
Eccentricity
i.e. how far a shape varies from a perfect circle where E=)
What is the range of eccentricity?
From 0 (perfect circle) to 1 (straight line)
What are Kepler’s three laws of planetary motion?
- the orbit of each planet around the sun is an elipse with the sun at one focus
- as a planet moves around its orbit it sweeps out equal areas in equal times (faster closer to the sun and slower the farther away it gets)
- more distant planets orbit the sun at slower speeds, obeying the relationship P^2 (p=orbital period) OC a3 (= average distance from sun in AU)
What does perihelion mean?
Close to the sun
What does aphelion mean?
Far from the sun
What were three rejections to the Copernican view?
- Earth could not be moving because objects in the air would be left behind
- heavens should be perfect therefore elipses can’t exist
- we would be able to detect stellar parallax
How did Galileo answer each refutal to the Copernican view?
- Galileo showed that a moving object will stay in motion unless a force acts to slow it down
- Galileo saw sunspots on the sun (imperfections) and mountains on the moon (like imperfect earth)
- Galileo showed that stars must be much father than they thought
What is science? Does all knowledge come from science?
Science = knowledge
- not all knowledge comes from science (ex. you can know your favourite band without a scientific theory for it)
What was the final evidence that Galileo showed, proving that the earth was not at the centre of the universe?
- discovered moons orbiting Jupiter (therefore not all object orbited the earth)
- observation of venus’s phases proved that it orbits the sun, not the earth
- in 1631, astronomers observed a transit of mercury across the sun’s face
What are the three characteristics of science?
- explanations of phenomena are based on natural causes (no supernatural forces considered)
- creation of models and testing them to discover the simplest explanation that fits
- the predictions must be testable
What are the necessary requirements for a scientific theory?
they must
- explain a wide variety of observations with a few simple explanations
- be supported by much evidence
- not have failed any major tests of validity
Is astrology accurate?
No; their predictions are no more accurate than by pure chance
