Astronomy Module 3

Tycho Brahe is noted for all of the following achievements except

innovative use of the telescope.

The Babylonians were important to the history of astronomy for all of the following EXCEPT:

measuring the diameter of Earth.

Which of the following observations provided the most direct challenge to the geocentric model of solar system orbits?

phases of Venus

Megaliths like Stonehenge provided astronomical information to ancient societies, including predictions of:

seasonal changes.

Which of the following characteristics were included in Ptolemy's model of the Universe?

All the planets, as well as both the Sun and the Moon, revolve about a fixed Earth. Planets move in circles on top of circles called epicycles. The heavens are perfect and unchanging. The nested set of crystalline, celestial spheres is maintained as proposed by Aristotle.

Who was the first astronomer to discover sunspots?

Galileo Galilei

Who was the first astronomer to make measurements of the sky with a telescope?

Galileo Galilei

The earliest ancient civilization known to have developed the geocentric model to explain the motions of the heavens was the:

Greeks.

Which of the following describes Kepler's approach and contributions to astronomy?

He constrained his models of planetary motion with the positional data from Tycho Brahe.

Which of the following does not describe a contribution that Galileo made to science?

He theorized that there was a mutually attractive force proportional to distance to explain how and why planets orbit the Sun.

Ptolemy's model of the Universe was accepted as valid for over a thousand years. Which of these is not one of the reasons for its acceptance?

It correctly put the Sun at the center.

The astronomer who formulated the three general laws of planetary motion was:

Johannes Kepler

In 1500s, Copernicus reintroduced the heliocentric model that the ancient Greeks had rejected, and it began to gain favor among some scientists. He suggested that the planets all orbit around the Sun in perfect circles, as shown in the figure to the right. This offers a much more elegant explanation of retrograde planetary motion than the geocentric model. What would be the next step in the scientific process for the Copernican heliocentric model?

Make predictions from Copernicus's model, and verify them with observations.

Choose the correct phases of Mars as seen by Earth from each of Earth's five different positions around its orbit compared to Mars.

Middle (between Sun and Mars) clockwise: A, C, B, L, K

Which of Galileo's observations disputed the perfect nature of the heavens above the sublunar region?

Mountains on the Moon; sunspots

The heliocentric model offered a simple explanation for retrograde motion, but the ancient Greeks determined that it was incorrect. Not only did the Earth feel like it was not moving, but the paradigm of the time was that Earth was special and thus had to be at the center of the universe. They did, however, consider the possibility that their paradigm was incorrect by testing the heliocentric model through the prediction that stellar parallax would exist if the Earth orbited around the Sun. Study the figure, which shows the line of sight between Earth and two stars. Choose the answer that most closely matches what we would observe in our sky, according to this figure, if the Earth orbits around the Sun.

Over the course of a year, stars should appear to move back and forth, with stars closer to us moving a larger distance.

Sort the following characteristics by the model of the solar system they describe: the Ptolemaic model, the Copernican model, or Kepler's laws of planetary motion.

Ptolemaic Model: Retrograde motion is explained by epicycles.; Earth at the center of the solar system.; Sky objects held by crystal spheres. Copernican Model: Planets orbit the Sun only on circular paths.; Introduced the idea of Earth's rotation. Kepler's Laws: P^2=R^3; Planets have elliptical orbits.; Planets orbit faster when near perihelion.

The astronomer who used the geocentric model to make accurate predictions of planetary positions was:

Ptolemy.

Place the following ancient astronomers in chronological order, from earliest to most recent:

Pythagoras, Aristotle, Hipparchus, Ptolemy.

The Greek figure most responsible for introducing mathematical explanations of natural phenomena was:

Pythagoras.

How does the heliocentric model explain the retrograde motion of Mars?

The heliocentric model explains retrograde motion because Mars only appears to move backward as Earth passes it in its orbit around the Sun.

Kepler's laws of planetary motion were formulated using data recorded by:

Tycho Brahe.

What was the first observation to challenge Aristotle's conception of perfect and unchanging heavens?

Tycho's supernova

In the heliocentric model, retrograde motion occurs when:

Earth catches and passes another planet in its orbit.

Sort the statements by whether they are a part of the geocentric (Earth-centered) model of the Solar System or the heliocentric (Sun-centered) model.

Geocentric: planets orbit on epicycles; no predicted stellar parallax; epicenter travels at constant speed Heliocentric: planets only ever orbit in one direction; stellar parallax is predicted; Venus travels behind the Sun

To explain the retrograde motion of planets, it was suggested that the Earth and planets orbit around the Sun (heliocentric, or Sun-centered model). The following image shows the orbits of Mars and Earth according to this model (toward the bottom of the image), with positions of each planet at specific times marked by numbers. Show how Mars would appear to move in relation to the stars (top of the image) by placing the numbered labels (at right) on the locations Mars would appear to be in the sky for the corresponding orbital positions. The apparent positions of Mars among the stars are shown by a row of small white dots. Lines connect these to the targets where you can place your labels. Tip: Mars will appear to be along the line of sight of Earth, where a straight line connecting Earth and Mars intersects with its apparent location on the celestial sphere. It may be helpful to use a straight-edge passing through the centers of Mars and Earth to extend Mars's apparent position among the stars.

Left to Right: E, B, C, D, A

From our vantage point on Earth, it looks like the Earth is stationary, and the Sun, Moon, stars, and planets are orbiting around us. Humans believed this geocentric (Earth-centered) view of the universe for the majority of history. The geocentric model of the universe looked like the left figure shown, with all celestial objects orbiting Earth in perfect circles. The brightest planets are visible to the naked eye, and they move through the background of the stars from one night to the next. Study the picture, which shows Mars's position with respect to the stars over the course of many nights. What can you conclude from this, assuming that the geocentric model holds that the Sun, Moon, and planets like Mars all orbit around Earth in simple circles?

The geocentric model is wrong because it falsely predicts that Mars should always move in the same direction with respect to the stars.

Which of the following most closely explains what we would see from Earth according to the geocentric model that includes epicycles?

The planets would usually move west to east through the stars, but they appear to reverse direction when they are on the part of the epicycle that has motion opposite to that of the larger circle.

Galileo was put on trial by the Catholic Church for:

publishing a book in support of the heliocentric model.

Ptolemy's formulation provided the first successful set of accurate predictions for the:

retrograde motion of the planets.