Flashcards in Lecture 7 Deck (36):
What asteroid will Osiris Rex visit?
Bennu, to pick up some soil samples
What did ancient civilizations use astronomy for?
Measuring time and space
When was Stonehenge built?
What were the first clocks/calendars based on?
The sun (Sundials)
What were the three things that allowed Greek civilization to develop astronomy?
1. tradition to understand nature w/out the supernatural 2. mathematics 3. Reasoning based on observations
Who developed the geocentric model in 400 bc?
How many planets did the Greeks expect?
What was unique about Thales' model of the universe?
The first one that didn't rely on supernatural forces
What Anaximander's model of the universe?
A cylinder floating in space surrounded by the celestial sphere
What did Pythagoras change about Anaximander's model?
The earth is a SPHERE
What were Anaxagoras's key hypotheses?
Earth and Heavens are made from the same elements and that the moon reflects light
Who first thought that the Earth rotates?
Who proposed heliocentric?
What did Eratosthenes measure?
The circumference of the Earth
Who proposed epicycles?
What did Ptolemy do?
He made many predictions, recorded in his Almagest
Who revived Aristarchus's sun-centered model?
How did Copernicus deal with the inaccuracy of circular orbits?
He added epicycles
What was Tycho Brahe's contribution?
He recorded the best naked eye observations, hired Kepler, and began to dismantle the stellar parallax, and discovered that planets go around the sun (with earth in the center)
What did Kepler finally decide?
Orbits had to be ellipses
Is the perihelion the short or long side?
Is the aphelion the short or long side?
What is Kepler's first law?
The orbit of each planet is an ellipse with the sun at one focus, which dispelled heavenly perfection
What is Kepler's second law?
A planet sweeps out equal distances at equal times (slower when further away)
What is Kepler's third law?
a planet orbiting further out orbits slower (p^2=a^3)
What was Thomas Digges's contribution?
He dismantled the stellar parallax, and proved that the universe was infinitely large with infinite stars at various distances
What three things did Galileo dismantle?
1. stellar parallax 2. non-circular orbits 3. Earth could not be moving because air would be left behind
How did Galileo prove that the heavens were imperfect?
He detected sunspots on the sun and mountains on moon
How did Galileo prove heliocentricity?
He used the phases of Venus
What did the Julian calendar add?
What did the Gregorian calendar add?
Fixed leap years and timing
What is the sidereal period?
The time it takes for a planet to orbit the sun
What is the apparent solar time?
The time when the sun appears highest
What is the mean solar time?
Average of all apparently solar times
What is the synodic period?
Time between when a planet is lined up with the sun and when it is lined up again