Astronomy Chapter 3

Kepler's third law of planetary motion:

T^2/R^3 has same value for every planet ( T = revolution, R = average distance)

What did Aristarchus propose?

earth was rotating on axis, and revolving around sun, and star shifts were too small to see

Which of Kepler's Laws governs how a particular planet speeds up and slows down?

equal area law

What's another name for kepley's second law of planetary motion?

equal area rule

Perihelion:

planet's closest approach to sun

Aphelion:

planet's farthest approach from sun

Epicycle:

small circular path

What did Kepler figure out?

orbits are ellipses

How precise were Tyco's angle instruments?

1/60 degree of arc

Copernicus said that the rotation of the Earth on its axis caused the: A. daily motion in the heavens B. phases of the moon C. retrograde motion of planets D. motion of sun along ecliptic

A

Aristarchus of Samos is known for a number of things. One of them was: A. the idea that an explanation or model should save the appearances. B. A model in which the Earth rotates on its axis and revolves around the Sun. C. A model of the Solar System in which the Earth is fixed and everything rotates around the Earth. D. the discovery that planets move on elliptical orbits around the Sun E. his measurement of the size of the Earth.

B

By making extensive observations of planetary motion, Tycho Brahe A. proved that Copernicus was right B. provided only a lot of accurate data. C. disproved Ptolemy's theory of planetary motion D. explained how planets move. E. discovered new planets.

B

Copernicus said that the daily motions in the heavens were caused by the A. planets speeding up and slowing down. B. earth turning on its axis. C. earth and the planets orbiting the Sun. D. planets turning on their axes E. planets moving on epicycles.

B

In addition to being accurate, Tycho Brahe's observations focused on measuring the positions of the planets A. near the horizon. B. all the time. C. when they were in retrograde motion. D. during conjunctions. E. during the solstices.

B

Jupiter is farther from the Sun than Mars. Which of the following statements is true? A. Jupiter takes longer to go around the Sun than Mars because it has farther to go, but actually moves faster than Mars B. Jupiter takes longer to go around the Sun than Mars and moves more slowly than Mars does C. Jupiter takes longer to go around the Sun than Mars because it has farther to go, but actually moves at the same speed as Mars D. Jupiter takes less time to go around the Sun than Mars and moves much faster E. Jupiter takes less time to go around the Sun than Mars does but moves slower because Mars keeps making rest stops.

B

Aristarchus of Samos is known for a number of things. One of them was A. A model of the Solar System in which the Earth is fixed and everything rotates around the Earth B. his measurement of the size of the Earth. C. A model in which the Earth rotates on its axis and revolves around the Sun. D. the idea that an explanation or model should save the appearances. E. the discovery that planets move on elliptical orbits around the Sun.

C

By making extensive observations of planetary motion, Tycho Brahe: A. discovered new planets B. explained how planets moved C. provided accurate data for the first time D. disproved Ptolemy's theory of planetary motion E. proved Copernicus was right

C

In comparison to the Copernican Theory, the Ptolemaic Theory made predictions that were of: A. much higher accuracy B. much less accuracy C. about same accuracy

C

Kepler found that the orbit of Mars is best described as A. a circle with the Sun off-center, combined with epicycles. B. a circle with the Sun at the center. C. an ellipse D. a complicated fourth-order polynomial curve.

C

Mars is farther from the Sun than Earth. Which of the following statements is true? A. Mars takes longer to go around the Sun than the Earth because it has farther to go, but actually moves faster than the Earth. B. Mars takes longer to go around the Sun than the Earth because it has farther to go, but actually moves at the same speed as the Earth. C. Mars takes longer to go around the Sun than Earth and moves more slowly than the Earth does. D. Mars takes less time to go around the Sun than the Earth and moves much faster E. Mars takes less time to go around the Sun than the Earth does but moves slower because the Earth keeps making rest stops.

C

One reason that the Copernican System failed to fit Tycho's observations was that: A. it placed the Earth at the center of the universe. B. it used elliptical orbits instead of circles. C. it used circular orbits instead of ellipses. D. it placed the Sun at the center of the system.

C

The Greek theory of Gravity as a force pulling everything toward the center of the universe implied that the Earth should be fixed at the center of the universe. Which of the following models of the Solar System was in accord with that theory? A. the Copernican System. B. the model of Aristarchus that the Earth goes around the Sun. C. none of these models. D. the final version of the Ptolemaic System

C

What did Kepler test and fail?

Copernican system

Who published De Revolutionibus Orbium Coelestium?

Copernicus

Tycho Brahe's careful observations of the planets agreed, to within observational error, with: A. copernican system B. ptolemaic system C. tychonic system D. none of these systems

D

Which of these was the Solar System model that assumed the Earth is fixed and the Sun, Moon, and planets all move on epicycles that, in turn move on circular orbits around the Earth? A. Keplerian model B. Tychonic model C. Copernican model D. Ptolemaic model

D

Which of these was the Solar System model that assumed the Earth is fixed and the Sun, Moon, and planets all move on epicycles that, in turn move on circular orbits around the Earth? A. Copernican Model B. Tychonic Model C. Keplerian Model D. Ptolemaic Model

D

The statement that the orbit of each planet is an ellipse with the Sun at one focus is due to

Kepler

The statement that the orbit of each planet is an ellipse with the Sun at one focus is due to who?

Kepler

Who published Astronomia Nova?

Kepler

Who was Tyco's assistant?

Kepler

What did Ptolemy create?

Ptolemaic model, which had sun and moon moving in epicycles around earth

Who became court astronomer in Denmark?

Tyco Brahe

Who pointed out that comets appeared in same constellation?

Tyco Brahe

What was the name of Tyco's castle, and how much of budget did it take?

Uraniborg, and 1% of budget

Kepler's second law of planetary motion:

a given planet moves fastest when closest to sun

Deferent:

a point

what did early astronomers assume?

celestial sphere existed and everything revolved around earth

The Ptolemaic model of the Solar System has each planet moving along a

circular epicycle whose center, in turn, moves around the Earth

what do earth's foci look like?

close together

What did Copernicus propose?

earth and planets were rotating around sun

Copernicus said that the retrograde motion of the planets was caused by the

earth and the planets orbiting the Sun

what do mars's foci look like?

far apart

Retrograde Motion:

looping backwards/westward

What did Tyco attempt to do?

measure positions of planets, time, and angles

As the two foci of an ellipse are moved apart, the shape of the ellipse becomes

more like a line between the foci

Kepler's first law of planetary motion:

orbit of each planet is an ellipse w/ sun at one focus

Retrograde Motion refers to the

westward motion of the planets relative to the stars.

When can an ellipse be an ellipse?

when foci are far apart

When can an ellipse be circular?

when two foci are at same point