Astronomy Chpt. 3

LG 3.3: How did Copernicus, Tycho, and Kepler challenge the Earth-centered model? What are Kepler's three laws of planetary motion? How did Galileo solidify the Copernican revolution?

1. Copernicus created a Sun-centered model of the solar system designed to replace the Ptolemaic model, but it was no more accurate than Ptolemy's because Copernicus still used perfect circles. Tycho's accurate, naked-eye observations provided the data needed to improve on Copernicus's model. Kepler developed a model of planetary motion that fit Tycho's data. 2.(1) The orbit of each planet is an ellipse with the Sun at one focus. (2) A planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times. (3) More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship p2 = a3. 3.Galileo's experiments and telescopic observations overcame remaining objections to the Copernican idea of Earth as a planet orbiting the Sun. Although not everyone accepted his results immediately, in hindsight we Venus Earth see that Galileo sealed the case for the Sun-centered solar system.

LG 3.2: Why does modern science trace its roots to the Greeks? How did the Greeks explain planetary motion?

1. The Greeks developed models of nature and emphasized the importance of agreement between the predictions of those models and observations of nature 2.The Greek geocentric model reached its culmination with the Ptolemaic model, which explained apparent retrograde motion by having each planet move on a small circle whose center moves around Earth on a larger circle

LG 3.4: How can we distinguish science from nonscience? What is a scientific theory?

1.Science generally exhibits three hallmarks: (1) Modern science seeks explanations for observed phenomena that rely solely on natural causes. (2) Science progresses through the creation and testing of models of nature that explain the observations as simply as possible. (3) A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions did not agree with observations. 2.A scientific theory is a simple yet powerful model that explains a wide variety of observations using just a few general principles, and that has survived repeated and varied testing

LG: 3.1 In what ways do all humans use scientific thinking? How is modern science rooted in ancient astronomy?

1.Scientific thinking relies on the same type of trial-and-error thinking that we use in our everyday lives, but done in a carefully organized way 2. Ancient astronomers were accomplished observers who learned to tell the time of day and the time of year, to track cycles of the Moon, and to observe planets and stars. The care and effort that went into these observations helped set the stage for modern science

What do we mean by a model in science? Briefly summarize the Greek geocentric model.

A scientific model is a conceptual representation created to explain and predict observed phenomena. ... In astronomy, the geocentric model is a description of the universe, or at least the Solar System, where the Earth is at the orbital center of all the celestial bodies

Why did ancient peoples study astronomy? Describe the astronomical origins of our day, week, month, and year?

Astronomy had practical benefits for timekeeping, keeping track of seasonal changes, and navigation. one day- time it takes for the sun to make one full curcuit of the sky. one month-moon cycle of phases. one year-cycle of seasons. 7 days named after 7 planets of ancient times

What was the Copernican revolution, and how did it change the human view of the universe?

Copernican revolution The dramatic change, initiated by Copernicus, that occurred when we learned that Earth is a planet orbiting the Sun rather than the center of the universe (65). For the longest time we thought the all the objects in the sky revolved around us, and that the earth was the center of the universe

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.

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.

What do we mean by the Ptolemaic model? How did this model account for the apparent retrograde motion of planets in our sky?

Ptolomy's model of the solar system was geocentric, where the sun, moon, planets, and stars all orbit the earth in perfectly circular orbits. The problem with perfectly circular orbit around the Earth is that they do not explain the occasional backward motion, or retrograde motion, of the planets

State and explain the meaning of each of Kepler's laws of planetary motion.

The first law states that planets move in an elliptical orbit, with the Sun being one focus of the ellipse. ... The third law states that the ratio of the squares of the orbital period for two planets is equal to the ratio of the cubes of their mean orbit radius.

What is an ellipse? Define its foci, semimajor axis, and eccentricity.

The locations of the two tacks are the foci of the ellipse. The long axis of the ellipse is the major axis and each half of the major axis is called a semimajor axis. The eccentricity of an ellipse describes to what extent an ellipse is stretched out in comparison to a circle

In what way is scientific thinking natural to all of us, and how does modern science build upon this everyday type of thinking?

We use scientific thinking naturally because that is how the human brain lives life through trial and error, modern science tries to simplify its finding so everyone can understand but it takes a lot of unnatural organizing.

Tycho Brahe's contribution to astronomy included

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

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.

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

the planet actually goes backward in its orbit around Earth.