chapter 21 physical science quiz

Why did Galileo's observation that Venus showed phases like the Moon indicate that the geocentric theory of the solar system was not possible?

It demonstrated that Venus could not be in orbit around Earth between Earth and the Sun because it shows "full" and "new" phases that would never occur with geocentric geometry.

Three laws of planetary motion were discovered by ________.

Johannes Kepler

The first modern astronomer to propose a Sun-centered universe was ________.

Nicolaus Copernicus

Axial precession is sometimes called the precession of equinoxes because it results in a gradual shift, relative to the celestial background, of the position where the Sun crosses the celestial equator at the equinox. Astrology is a mythology based on things like your "sign" which refers to the position of the Sun in the celestial zodiac (the 12 constellations along the ecliptic) on your birthday. This system was established almost two thousand years ago. If this mythology were true (and you believe your horoscope) can you use the dates for your "sign" based on this 2000 year old system?

No, because 2000 years is almost 1/12, or one full sign shift, in the zodiac, so the 2000 year old signs are off by almost one full sign.

Why do the planets "drift" east relative to the stars and then move west for periods of time?

They are moving in the same rotation sense as the earth around the Sun, but as the earth moves faster (or slower, depending on the planet) the motion appears to be backwards.

How did Eratosthenes estimate the size of Earth?

They measured the angle of the Sun above the horizon at midday in two places with different latitude and used the angle to estimate the circumference of Earth.

A statement you will sometimes hear people say is that a day is not 24 hours but is really 23 hr. 56 min. and 4 sec. What does this refer to?

This is sidereal time, not solar time; a solar day is 24 hours.

Patterns or configurations of stars named in honor of mythological characters are called ________.

constellations

In the Ptolemaic (Greek) model of the universe, ________.

earth was in the center of the universe

A total eclipse of the Sun is only possible at ________.

new moon

This scientist determined the nature of the forces that kept the planets in their orbits.

sir Isaac newton

Which of these men formulated the Law of Universal Gravitation?

sir Isaac newton

The 5000 year old Stonehenge stone circle of Salisbury Plains, England, allows light shafts to come straight between two rocks on ________ in the Northern hemisphere.

summer solstice

What is the modern explanation for what the ancient Chinese called "guest stars"?

they are nova or supernova

The belt of constellations through which all the planets move is called the ________.

zodiac