Astronomy Homework 3

3.20 Newton's law of gravity works as well for explaining orbits of planets around other stars as it does for explaining the planets in our own solar system.

science

2. The names of the seven days of the week are based on the

seven naked-eye objects that appear to move among the constellations.

40. What do scientists mean by verifiable observations?

statements that a person can, in principle, verify for himself or herself

32. One of the "nails in the coffin" for Earth-centered universe was

Galileo's observations of the moons of Jupiter.

43. What is meant by Occam's Razor?

the idea that scientists should prefer the simpler of two models that agree equally well with observations

3.03 The ancient Greeks get a lot of attention for their contributions to science because _________.

they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural

20.Why did Ptolemy have the planets orbiting Earth on "circles upon circles" in his model of the universe?

to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky

3.07 The great contribution of Tycho Brahe was to _________.

observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion

22. During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in

Baghdad.

29. When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not?

Copernicus used perfect circles for the orbits of the planets.

33.When we see Venus in its full phase, what phase would Earth be in as seen by a hypothetical Venetian?

Full

27. He discovered that Jupiter has moons.

Galileo

28. He discovered what we now call Newton's first law of motion.

Galileo

19. How did the Ptolemaic model explain the apparent retrograde motion of the planets?

It held that the planets moved along small circles that moved on larger circles around Earth.

3.27 According to Kepler's third law:

Jupiter orbits the Sun at a faster speed than Saturn.

When would you expect to see Venus high in the sky at midnight?

Never

3.08 Which of the following was NOT observed by Galileo?

Stellar parallax

3.09 Which of the following statements about an ellipse is NOT true?

The focus of an ellipse is always located precisely at the center of the ellipse. Which of the following statements about an ellipse is not true?

48. Could acupuncture be responsible for the patients' recovery?

Yes. Just because we don't understand the mechanism doesn't mean the process does not occur.

41. What is meant by a scientific paradigm?

a generally well-established scientific theory or set of theories

3.04 What do we mean by a geocentric model of the universe?

a model designed to explain what we see in the sky while having Earth located in the center of the universe

38. Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that

a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.

18. When did Ptolemy live?

about 2000 years ago

30. When did Copernicus live?

about 500 years ago

3.05 What was the Ptolemaic model?

an Earth-centered model of planetary motion published by Ptolemy

42. What is meant by a hypothesis?

an explanation for a phenomenon that makes a prediction

Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?

at noon

When would a new Venus be highest in the sky?

at noon

8. At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral

at noon on the summer solstice.

3.02 Scientific thinking is _________.

based on everyday ideas of observation and trial-and-error experiments

21. Where was the Sun in Ptolemy's model of the universe?

between the orbits of Venus and Mars

3.21 God created the laws of motion that were discovered by Newton.

falls into the realm of nonscience

14. When and where did the Library of Alexandria exist?

from 300 B.C. to A.D. 400 in Egypt

31. Which of the following was not observed by Galileo?

stellar parallax

49. Must acupuncture be responsible for the patients' recovery?

No. Acupuncture may be responsible for the healing, or it may not. Correlation does not necessarily imply causation.

3.10 Which of the following claims can be tested by scientific means?

People born when the Sun is in the constellation of Leo are more financially successful than other people.

1. People of central Africa predicted the weather by

People of central Africa predicted the weather by observing the orientation of the crescent Moon relative to the horizon.

Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's second law?

Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.

3.30 Which of the following is not true about scientific progress?

Science advances only through the scientific method.

Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's first law?

(Check all that apply.) *Earth is slightly closer to the Sun on one side of its orbit than on the other side. *The Sun is located slightly off-center from the middle of each planet's orbit.

37. From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to

4 astronomical units.

39. All the following statements are true. Which one follows directly from Kepler's third law?

Venus orbits the Sun at a slower average speed than Mercury.

Consider again the set of observations from Part A. This time, classify each observation according to whether it is consistent with only the Earth-centered model, only the Sun-centered model, both models, or neither model. (Note that an observation is "consistent" with a model if that model offers a simple explanation for the observation.)

(Earth-centered only) - a planet beyond Saturn rises in west, sets in east (Sun-centered only) - Mercury goes through a full cycle of phases - positions of nearby stars shift slightly back and forth each year (Both models) - stars circle daily around north or south celestial pole - moon rises in east, sets in west each day - a distant galaxy rises in east, sets in west each day (Neither model) - we sometimes see a crescent Jupiter

Let's start with an example from history. Listed below are a series of claims regarding United States President John F. Kennedy (1917-1963). Classify each statement according to whether or not it is falsifiable.

(Falsifiable: could be proven false) - Kennedy was the 35th president of the United States - Kennedy died from a bullet in his brain (Not falsifiable: could not be proven false) - Kennedy's death was the will of God - The murder of John F. Kennedy was an act of evil - If he'd lived, Kennedy would have ended the Vietnam War - Kennedy's murder was orchestrated by an undetectable shadow government of the United States

Consider the following observations. Classify each observation based on whether it is a real observation (a true statement of something we can actually see from Earth) or one that is not real (a statement of something that does not really occur as seen from Earth).

(Real:true statements) - Mercury goes through a full cycle of phases - Moon rises in east, sets in west each day - stars circle daily around north or south celestial pole - positions of nearby stars shift slightly back and forth each year - a distance galaxy rises in east, sets in west each day (Not real:false statements) - we sometimes see a crescent Jupiter - a planet beyond Saturn rises in west, sets in east

We never see a crescent Jupiter from Earth because Jupiter __________.

*Is farther than Earth from the Sun

Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p2=a3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law?

*Venus orbits the Sun faster than Earth orbits the Sun *Inner planets orbit the Sun at higher speed than outer planets

Consider the hypothetical observation "a planet beyond Saturn rises in west, sets in east." This observation is not consistent with a Sun-centered model, because in this model __________.

*the rise and set of all objects depend only on Earth's rotation

44. Which of the following statements about scientific theories is not true?

A theory cannot be taken seriously by scientists if it contradicts other theories developed by scientists over the past several hundred years.

3.31 Which of the following is not true about a scientific theory?

A theory is essentially an educated guess.

35.Kepler's third law, p2 = a3, means that

All of the above are correct.

3.26 Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July.

3.01 What practical value did astronomy offer to ancient civilizations?

It helped them keep track of time and seasons, and it was used by some cultures for navigation.

3.24 Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model?

It made significantly better predictions of planetary positions in our sky.

26. He discovered that the orbits of planets are ellipses.

Kepler

34. Which of the following is not one of, nor follows directly from, Kepler's laws?

The force of attraction between any two objects decreases with the square of the distance between their centers.

3.23 In the Greek geocentric model, the retrograde motion of a planet occurs when:

The planet actually goes backward in its orbit around Earth.

The video states that the planetary orbits are shown to scale. Which statement correctly describes the way the planet sizes are shown compared to their orbits?

The planets are all much too large compared to their orbits.

In Ptolemy's Earth-centered model for the solar system, Venus always stays close to the Sun in the sky and, because it always stays between Earth and the Sun, its phases range only between new and crescent. The following statements are all true and were all observed by Galileo. Which one provides evidence that Venus orbits the Sun and not Earth?

We sometimes see gibbous (nearly but not quite full) Venus.

15. How did Eratosthenes estimate the size of Earth in 240 B.C.?

by comparing the maximum altitude of the Sun in two cities at different latitudes

3.28 Tycho Brahe's contribution to astronomy included:

collecting data that enabled Kepler to discover the laws of planetary motion.

3.14 Several kilometers below its surface, Jupiter's moon Europa has an ocean of liquid water.

could be evaluated scientifically

3.06 The great contribution of Nicholas Copernicus was to _________.

create a detailed model of our solar system with the Sun rather than Earth at the center

In Ptolemy's Earth-centered model for the solar system, Venus's phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.

full whenever it is on the opposite side of the Sun from Earth, although we cannot see the full Venus because it is close to the Sun in the sky

11. The Jewish calendar is kept roughly synchronized with a solar calendar by

having a thirteenth month with 5 days each year.

3.25 When we say that a planet has a highly eccentric orbit, we mean that:

in some parts of its orbit it is much closer to the Sun than in other parts.

3.32 When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been:

incomplete

3.29 Galileo's contribution to astronomy included:

making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

36. From Kepler's third law, a hypothetical planet that is twice as far from the Sun as Earth should have a period of

more than 2 Earth years.