Ch 3 : History of astronomy Flashcards
What were the purposes of ancient astronomy?
- predict weather patterns (seasons and such)
2. To assist travelers
Give two examples of tools ancient astronomers built?
Mayan pyramids, stonehenge
How much do the stones weigh in stonehenge? How far were they transported? What events do the stones align with?
Built over 1700 years ago. (2800BC)
50 tonne stones. 200km.
summer solstice sunrise aligns with the heel stone. alignments for the winter solstice and Equinoxes are also evident.
List three other ancient calendars
wooden circles in UK
Big horn medicine wheel, Wyoming
Chaco Canyon Sun Dagger.
What nation discovered guest stars? what were they?
Chinese.
the guest stars were supernovas, ike SN-1054 (now the crab nebula).
they also made super detailed maps of the stars
Where did the term Zenith and Azimuth come from?
what else did these people name?
Arabic astronomers.
also named stars like Betelguese and Rigel.
in additiion they had a mathimatical understanding of the moon’s behavior.
Which of these space objects was NOT catalogued by ancient astronomers? A. Planets B. Asteroids C. Supernova D. Stars E. Comets
Asteroids.
What are main accomplishments of ancient Greek astronomers?
distinguished between planets and stars (and the sun and moon. knew they were all diff types of objects)
(planet= wanderers)
also realized planets moved along the ecliptic,, and occasionally moved in retrograde.
What did Plato believe?
424-347BCE
PErfection of the heavens.
objects are circles. orbits are circles. I am a circle. perfect circles. wow.
even the stars orbit all together in one big sphere.
Circles.
Eudoxus
who is he?
what did he do?
Plato’s student
developed a system of 27 spheres to describe the motion of the heavens mathmatically.
this was accurate for up to five months.
Aristotle
where do his arguments stem from?
what did he actually do?
384-322BCE
All of his argeuments stemmed from first principles, which were beliefs that are obviously true. (nat stae of objects is to be at rest, so obvs, the earth is also at rest)
this idiot was considered an authority on a lot of things, and he really set us back.
He modified Euxdoxus’s 27 spheres to a 55 sphere model.
Aristarchus
what’s his deal?
310-230 BCE
propsed the idea that the earth rotated around the sun.
also the first person to wonder how far away the sun is.
he tried to calculate it with triangulation, but was pretty far off.
thanks to Ari prime, he was ignored.
Eratosthenes
276-195 BCE
calculated the radius of the earth by measuring the angle of the shadow in two different cities.
he was accurate to 10%
hot damn, boi
Ptolemy
what did he do?
why was he good?
Made an advanced mathamatical model of geocentric universe.
used deferent (primary path) and epicycles ((an orbit around a point on the deferent).
needed 80 spheres to describe motion
model held for centuries, but was a little off.
Which of these is not explained by Ptolomy’s geocentric model?
a. The noon Sun changes position/height in the sky with the seasons
b. The Earth appears to be flat
c. Sun, Moon and stars follow smooth paths
d. The planets periodically travel in retrograde
e. The Earth feels like it is stationary
b. earth appears to be flat
Copernicus
what was his deal?
was his model superior to Ptolematic model?
HE developed a heliocentric model, that could NOT predict planetary motion.
used 9 spheres.
not superior bc he couldn’t predict movements of planets, even though he had a cleaner explaination for retrograde motion (no epicycle).
What are the six principles of the copernician model?
- Orbits are circular
- There isn’t one common center of orbit.
- the Earth is centre of all gravity and moon’s orbit. the planets orbit the sun and have no gravity.
- the stars are much much farther away.
- the motion of the stars and the Sun is due to rotation of earth on it’s own axis.
- the retrograde motion of the planets is due to Earth’s orbit.
What were galileo’s
revolutionary observations via telescope? (4)
- Moon had craters
- Sun had spots
(perfect artisotle? I think not) - Saw four of jupiter’s moons.
(our moon isn’t special, they can orbit things other than earth) - venus’s phases didnot match up with a geocentric model