EAS test 21

At the beginning of spring, the vernal equinox, what is the right ascension of the sun?

0

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

3

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?

5.2

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

A year measured in sidereal time would be about one ay longer than a year based on solar time

Galileo Aristotle Kepler Newton

Aristotle

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

Axial precession

The apparent path of the Sun upon the celestial sphere is called the _______

Ecliptic

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

Galileo

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

Galileo

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

He made very precise measurements that were key data used by Kepler

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 showed that Venus could not be in orbit around the earth between the earth and the sun because it shows "full" and "new" phases that would never occur in geocentric geometry

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

Johannes Kepler

Three laws of planetary motion were discovered by ________.

Johannes Kepler

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?

Look for the brightest star in the constellation Centaurus

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

Nicolaus Copernicus

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

Nicolaus Copernicus

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, recuasse 2000years 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

declination right ascension perihelion equatorial system

Perihelion

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

Perturbation

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

RA indeterminate, D 90 degrees

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

Several degrees from the North Pole position, with Vega as the North Star

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

Sidereal

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 Issac Newton

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

Synodic

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?

The ellipticity of the orbit is small, so the affect is small; seasons are caused by the tilt of the earths orbit

Why are there only 4-7 eclipses per year

The moons orbit is inclined to the ecliptic and only crosses the ecliptic 2 times per year

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?

The sidereal time, not solar time; a solar day is 24 hours

A sidereal day is defined as _______

The time for one complete revolution of the earth relative to the celestial reference

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

They are Nova or Supernova.

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 the Greeks estimate the size of the 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 the earth.

Why were planets called "wanderers" by early Astronomers?

They move relative to the stars

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?

When Jupiter and Mars align in the sky and the moon is in the 7th constellation of the zodiac, then peace...

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?

Yes, it visible in Hawaii during the summer months

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

celestial sphere

rotation revolution precession declination

declination

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

determine when to plant crops or hunt animals based on seasonal changes

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

earth was in the center of the universe

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

eastward

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

ellipses

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

it is rotating around the sun slower than the earth's rotation

A total eclipse of the Sun is only possible at _______

new moon

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

new moon

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?

on the Southern Hemisphere summer solstice, around Dec 21

The length of daylight on the Moon is about _______

one month

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

retrograde motion

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

seven

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

stars that go Nova or Supernova and appear as bright objects during the event

During a total lunar eclipse, the moon remains visible because _______

the atmosphere of the earth refracts light around it perimeter

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?

the move along the zodiac

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

the two moons of Mars

Relative to the celestial background, the moon moves ________

west to east

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

zodiac