Chapter 21 Earth Science – Flashcards

According to the Ptolemaic (Greek) model of the universe, how many "heavenly" bodies could be observed wandering along the background of stars?

Why were planets called "wanderers" by early Astronomers?

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

The apparent westward "drift" of the planets compared to background stars is called _______.

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

In the Ptolemaic (Greek) model of the universe, the stars are attached to the ________.

How did the Greeks estimate the size of the earth?

What is the modern explanation for "guest stars" that appear in the night sky and then disappear?

The earliest astronomical records appear to have been made by the ancient Chinese, Egyptians, and Babylonians in order to ________.

Planets appear to move ________ each night, but occasionally they appear to stop and reverse direction.

When viewing the planets, Mars appears to move backwards, or retrograde, because ________.

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

One of the discoveries which led to the modern view of the solar system was that the orbits of the planets are ________.

Galileo observed several features using the telescope. Which one of the following did he not discover?

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

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

This scientist was the first to use the telescope in astronomy.

Three laws of planetary motion were discovered by ________.

The true shape of the planetary orbits was discovered by ________.

Who wrote the book entitled Of the Revolutions of Celestial Spheres (De Revolutionibus)?

This scientist wrote a book entitled Dialogue of the Great World Systems that compared the Earth-centered system with the Sun-centered system.

Which of these men formulated the Law of Universal Gravitation?

Any variance in the orbit of a planet from its predicted path is referred to as ________.

Tyco Brahe set out to disprove Copernicus, so why is he famous for developing modern astronomical theory?

Kepler's third law states that the planet's orbital period squared is equal to its mean solar distance cubed. Consequently, the solar distances of the planets can be calculated when their periods of revolution are known. The orbital period of Jupiter is 12 years, what is its distance from the sun in astronomical units?

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

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

Astrology is the folklore that arose from watching alignments in the night sky and the belief that these "celestial events" controlled human events. A 1960's folk song, "The Age of Aquarius" has numerous astrology references that relate to the positions of objects in the sky. The song has a line: "When the moon is in the 7th house, and Jupiter aligns with Mars, then peace will guide the planet..." From your knowledge of the stellar constellations and the celestial coordinate system, what does this line mean?

The planets are "wanderers" in the night sky because they move relative to the stars. However, there movement is limited to the plane of the solar system, which is disk shaped. So relative to the celestial coordinate system, how do the planets actually move across the sky?

Alpha Centauri is a famous star because it is one of the closest stars to earth (other than the sun of course). Where would you look in the night sky for Alpha Centauri?

Think about the correlation of the celestial coordinate system, the tilt of the earth's axis, and the positions on Earth. If you are an observer in the Southern Hemisphere, 2 degrees north of the Tropic of Capricorn, What time of year will you be able to see the North Star?

The Southern Cross is a Southern Hemisphere constellation that is as famous the big dipper in the Northern Hemisphere because of the brightness of the stars. It has a Southern Hemisphere declination slightly higher than the big dipper's Northern Hemisphere declination. Is it visible anywhere in the United States?

What is the right ascension and declination for Polaris, the North Star?

Earth hits its perihelion position in January. Solar radiation is proportional to the distance squared between the sun and the earth, so why isn't it hot in "winter" at perihelion?

Where will the North Star be, relative to the celestial coordinates, 12,000 years from now?

The ________ day is the time it takes for Earth to make one complete rotation with respect to a star other than our Sun.

A slow motion of Earth's axis that requires 26,000 years to complete is called ________.

The apparent path of the Sun upon the celestial sphere is called the ________.

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?

A sidereal day is defined as ________.

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?

If you determine the number of days in a year with solar time and sidereal time how would they vary?

The length of daylight on the Moon is about ________.

The period of time required for the Moon to complete a cycle of phases is called the ________ month.

Relative to the celestial background, the moon moves ________.

When the moon appears as a thin crescent in the evening sky, just after sunset, the lunar phase is ________.

At first quarter it is approximately ________ week(s) until the new moon.

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

During a total lunar eclipse, the moon remains visible because ________.

Why are there only 4-7 eclipses per year?