AY 101 002 CH 3 HW
How far does the planet in part F orbit from the Sun?
10 AU
Tycho Brahe's contribution to astronomy included:
collecting data that enabled Kepler to discover the laws of planetary motion.
Which of the following is not true about a scientific theory?
A theory is essentially an educated guess.
In Carl Sagan's statement "Extraordinary claims require extraordinary evidence," what does he mean by "extraordinary evidence"?
Evidence that is extremely strong.
When would a new Venus be highest in the sky?
at noon
Approximately how fast is Jupiter orbiting the Sun?
a little less than 15 km/s
Uranus, not shown on the graph, orbits about 19 AU from the Sun. Based on the graph, its approximate orbital speed is between about __________.
5 and 10 km/s
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? Check all that apply. - The Sun is located slightly off-center from the middle of each planet's orbit. - Venus orbits the Sun faster than Earth orbits the Sun. - All the planets orbit the Sun in nearly the same plane. - Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. - Inner planets orbit the Sun at higher speed than outer planets. - Earth is slightly closer to the Sun on one side of its orbit than on the other side.
- Venus orbits the Sun faster than Earth orbits the Sun. - Inner planets orbit the Sun at higher speed than outer planets.
Suppose (Figure 1) showed a planet on the red line directly above a value of 1000 AU3 along the horizontal axis. On the vertical axis, this planet would be at __________.
1000 years ^2
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.
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 - If he'd lived, Kennedy would have ended the Vietnam War - The murder of John F. Kennedy was an act of evil - Kennedy's murder was orchestrated by an undetectable shadow government of the United States
Let's now consider possible scientific claims. Recall that a scientific claim is falsifiable if it could in principle be shown to be false by observations or experiments, even if those observations or experiments have not yet been performed. Classify each claim according to whether or not it is falsifiable.
FALSIFIABLE (could be proven false) : - The Sun is at the center of the solar system - The observable universe contains approximately 100 billion galaxies - Earth is at the center of the solar system - The chemical content of the universe is mostly hydrogen and helium NOT FALSIFIABLE (could not be proven false) : - We are all playthings in a computer program created by advanced aliens - The universe was created by God - The laws of nature are magnificent and beautiful
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.
According to Kepler's third law:
Jupiter orbits the Sun at a faster speed than Saturn.
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 - A distant galaxy rises in east, sets in west each day - Stars circle daily around north or south celestial pole - Moon rises in east, sets in west - Positions of nearby stars shift slightly back and forth each year NOT REAL (false statements) : - We sometimes see a crescent Jupiter - A planet beyond Saturn rises in west, sets in east
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
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
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.
When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been
incomplete
Galileo's contribution to astronomy included:
making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.
When would you expect to see Venus high in the sky at midnight?
never
On (Figure 1), you can see Kepler's third law (p ^2=a ^3) from the fact that __________.
the data fall on a straight line
Kepler's third law is often stated as p ^2=a ^3. The value a ^3 for a planet is shown on __________.
the horizontal axis of Figure 1
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 depends only on Earth's rotation
Listed below are a series of statements about events that first happened in one of the four time periods identified in the sorting bins. Place each statement in the correct bin corresponding to when it first occurred in human history.
ANCIENT GREECE THROUGH PTOLEMY (about 150 A.D.) : - Suggestion that Earth might orbit the Sun - Recognition that Sun-centered model should lead to stellar parrallax - Ability to predict planetary positions within a few degrees of arc EARLY COPERNICAN REVOLUTION (about 1543-1600) : - Copernicus proposes Sun-centered model - Planetary observations accurate within 1 minute of arc LATER COPERNICAN REVOLUTION (about 1609-1630) : - Ability to predict planetary positions within 1 minute of arc - Observation of phases of Venus - Sun-centered model with elliptical orbits NEWTON AND BEYOND (after about 1687) : - Mathematical descriptions of how gravity determines planetary orbits - Observations of stellar parallax
How does its average distance compare to that of Pluto
Eris orbits farther than Pluto.
In which of the four time periods did the Sun-centered model gain widespread acceptance, meaning that nearly everyone who looked at the evidence concluded that it was correct?
Later Copernican Revolution (about 1609-1630)
"A huge fleet of alien spacecraft will land on Earth and introduce an era of peace and prosperity on January 1, 2035."
The claim can be evaluated scientifically by seeing whether or not the aliens show up on the appointed date.
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.
An asteroid with an average orbital distance of 2 AU will orbit the Sun at an average speed that is __________.
a little slower than the orbital speed of Mars
We never see a crescent Jupiter from Earth because Jupiter __________.
is farther than Earth from the Sun
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? Check all that apply. - Inner planets orbit the Sun at higher speed than outer planets. - 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. - Venus orbits the Sun faster than Earth orbits the Sun. - All the planets orbit the Sun in nearly the same plane. - Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
- Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
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. - Inner planets orbit the Sun at higher speed than outer planets. - Venus orbits the Sun faster than Earth orbits the Sun. - The Sun is located slightly off-center from the middle of each planet's orbit. - Earth is slightly closer to the Sun on one side of its orbit than on the other side. - All the planets orbit the Sun in nearly the same plane. - Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
- The Sun is located slightly off-center from the middle of each planet's orbit. - Earth is slightly closer to the Sun on one side of its orbit than on the other side.
Part complete Which of the following were key pieces of evidence that led to widespread acceptance of the Sun-centered model "extraordinary claim" during the period from about 1609 to 1630? Select all that apply. - The fact that the Copernican model explained apparent retrograde motion of the planets. - Observations of stellar parallax. - The fact that Kepler's laws allowed virtually perfect prediction of planetary positions. - Galileo's telescopic observations. - The discovery of planets around other stars.
- The fact that Kepler's laws allowed virtually perfect prediction of planetary positions. - Galileo's telescopic observations.
Which of the following is not true about scientific progress?
Science advances only through the scientific method.
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
What is its average distance (semimajor axis) from the Sun? Express your answer using three significant figures.
a = 67.7 AU
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 fourth each year BOTH MODELS: - A distant galaxy rises in east, sets in west each day - Stars circle daily around north or south celestial pole - Moon rises in east, sets in west NEITHER MODEL: - We sometimes see a crescent Jupiter
