Ast 101

One arcminute is equal to

1/60 degree

The following distance units, arranged in size from smallest to largest, are

km, AU, ly, pc

Heavy elements, such as those throughout Earth and within our bodies, appear to have been formed

deep inside some now-vanished star

In science, if new observations disagree with a well established theory then

the theory must be modified

According to the scientific method, a hypothesis that is proposed to explain a particular physical phenomenon is considered wrong if:
a. it appears to defy logic and logical reasoning.
b. leading scientists in the world believe it is wrong.
c. it disagree

D) it is in conflict with the results of just one reliable and repeatable observation

Astronomers sometimes announce they have discovered a new solar system beyond our own, or a new galaxy beyond our own. Which choice correctly describes the terms "solar system" and "galaxy"?
a. A solar system consists of planets and other objects orbiting

A) A solar system consists of planets and other objects orbiting around a star, whereas a galaxy is a system consisting of an immense number of stars.

In modern astronomy, the constellations are:
a. clusters of stars that are held together by the mutual gravitational attractions of the individual stars in the cluster.
b. nearby galaxies to which astronomers have given specific names.
c. 88 regions of sk

C) 88 regions of sky, covering the entire sky

The nightly motion of objects across our the sky is caused by the:
a. rotation of Earth on its axis.
b. revolution of Earth around the Sun.
c. motion of the solar system around the galaxy.
d. rotation of the whole celestial sphere of stars around the fixe

A) rotation of Earth on its axis.

When we watch the nighttime sky, we find that:
a. most stars and constellations slowly rise in the east, pass overhead, and set in the west.
b. the stars and constellations remain fixed in our sky, not rising or setting in a time as short as one night bec

A) most stars and constellations slowly rise in the east, pass overhead, and set in the west.

Imagine a bright star in the night sky. You watch it rise above the eastern horizon about 2 A.M. in the middle of February. About what time will it rise in the middle of March?
a. 4 A.M.
b. 10 P.M.
c. 2 A.M.
d. midnight

D) midnight

The ecliptic is defined as the
Select one:
a. line traced in our sky by the Sun over one year against the background stars.
b. line in the sky that is perpendicular to Earth's spin axis.
c. line traced in our sky by the Moon each month against the backgro

A) line traced in our sky by the Sun over one year against the background stars.

The ecliptic crosses the celestial equator at:
a. one point only, known as the vernal equinox.
b. two points, known as solstices.
c. the meridian.
d. two points, known as equinoxes.

D) two points, known as equinoxes.

What is the primary cause of Earth's seasons?
Select one:
a. The orbit of Earth is an ellipse, so Earth is not always the same distance from the Sun.
b. Earth's rotation axis tilts with respect to the plane of its orbit around the Sun.
c. Earth's precessi

B) Earth's rotation axis tilts with respect to the plane of its orbit around the Sun.

The vernal equinox is one time of the year when the Sun:
a. crosses the Moon's orbital path in the sky.
b. is at its lowest point in the sky at midday.
c. crosses the ecliptic plane.
d.crosses the celestial equator.

D) crosses the celestial equator.

In San Luis Obispo, how many times during the year will the Sun pass precisely through your zenith (that is, directly on top of you)?
Select one:
a. once
b. every day for a half a year
c. never
d. twice

C) never

Precession is
Select one:
a. the daily spinning motion of Earth, producing the apparent motion of the Sun and the stars.
b. the motion of Earth along its orbital path during a year.
c. the slow coning motion of the spin axis of Earth, similar to that of a

C) the slow coning motion of the spin axis of Earth, similar to that of a spinning top.

A science fiction writer, writing a story about inhabitants on Earth in 14,000 A.D. who have survived a disaster that included the loss of modern navigational aids, describes them traveling due north across barren wastes by walking toward Polaris, the Pol

B) Polaris will no longer be due north, because of Earth's precession.

By observing the sky closely night by night, you would note that a particular star rises
Select one:
a. about 4 minutes earlier every night.
b. about 4 minutes later every night.
c. at the same time every night.
d. at a varying time every night, sometimes

A) about 4 minutes earlier every night.

A solar day is the time it takes Earth to rotate around its axis between two consecutive solar positions (i.e. high noon to high noon or sunset to sunset). A sidereal day is the time it takes Earth to rotate around its axis between two consecutive positio

c. A solar day is always longer.

Why do we see different phases of the Moon?
Select one:
a.The rotation of the Moon around its own axis causes us to see different amounts of the sunlit side of the Moon.
b.The distance of the Moon from Earth changes because of the elliptical orbit of the

c. The motion of the Moon in its orbit around Earth causes us to see different amounts of the sunlit side of the Moon.

Eclipses of the Moon can occur only
Select one:
a. at new Moon.
b. in June and December, when the Sun is near the solstices.
c. in the spring and fall, when the Sun is on the ecliptic plane.
d. at full Moon.

D) at full Moon

During a solar eclipse, the
Select one:
a. Moon comes between Earth and the Sun.
b. Sun comes between Earth and the Moon.
c. Earth comes between the Sun and the Moon.
d. Sun goes below the horizon.

A) Moon comes between Earth and the Sun.

The maximum number of eclipses (both solar and lunar) that can occur in one calendar year is
Select one:
a. one.
b. seven
c. two
d. five

B) seven

In a period of 1 month, the Moon moves across the sky
Select one:
a. precisely along the celestial equator.
b. parallel to the horizon.
c. precisely along the ecliptic plane.
d. along a plane that is neither the ecliptic plane nor the celestial equator, n

D) along a plane that is neither the ecliptic plane nor the celestial equator, nor is it parallel to the horizon.

A lunar eclipse does not occur at every full moon because
Select one:
a. a lunar eclipse cannot occur after sunset.
b. the path of the Sun is inclined at an angle of 5� to the ecliptic plane.
c. the plane of the Moon's orbit is at an angle to the plane of

C) the plane of the Moon's orbit is at an angle to the plane of Earth's orbit.

When in total lunar eclipse, the Moon shows
a reddish color because
Select one:
a. light from the northern and southern lights (the aurora) on Earth, which is predominantly red, illuminates the Moon.
b. this is the color of the residual thermal glow from

C) only the red part of the solar spectrum is deflected onto it by Earth's atmosphere.

We can occasionally see a total eclipse of the Sun on Earth and the solar corona because
Select one:
a. the Sun is closer than the Moon
b. the angular sizes of Sun and Moon, when viewed from Earth, are almost the same.
c. both the Moon and Sun move precis

b. the angular sizes of Sun and Moon, when viewed from Earth, are almost the same.

A total lunar eclipse can last more than an hour and a half, but a total solar eclipse never lasts more than 7 1/2 minutes. Why this difference?
Select one:
a. A total solar eclipse always occurs when Earth is at perihelion, and it is moving fastest at th

c. Earth's shadow at the Moon's distance is much larger than the Moon's shadow at Earth's distance. As Earth rotates, this narrow lunar shadow sweeps quickly over any given spot.

The word planet is derived from a Greek term meaning
Select one:
a. wanderer.
b. astrological sign.
c. bright nighttime object.
d. non-twinkling star.

a. wanderer

The Ptolemaic model of the universe included each of the following features, except one. Which one is the exception?
Select one:
a. The planets move in circular orbits called epicycles. The centers of the epicycles move along circular orbits called defere

c. The apparent daily motion of the stars is due to the rotation of Earth.

What was the most important difference in development between Isaac Newton's theory of planetary motion and that of Johannes Kepler?
Select one:
a. Newton based his theory on accurate telescopic observations, whereas Kepler used observations made by eye.

d. Newton developed his theory from first physical principles, whereas Kepler found the model that provided the best fit to the data

Which one of the following statements describes the Newtonian understanding of the mechanics of the solar system?
Select one:
a. The natural motion of the planets, asteroids and comets would be that of a straight line if there was no gravitational pull fr

a. The natural motion of the planets, asteroids and comets would be that of a straight line if there was no gravitational pull from the Sun. Since there is, they move in one of four possible trajectories (circle, ellipse, parabola, or hyperbola)

Suppose I am at Earth's equator at a time when my location is experiencing a high tide that is higher than usual. What is happening one quarter of the way around the equator at this same time?
Select one:
a. This location will experience an exceptionally

a. This location will experience an exceptionally low tide.

In 1675, R�mer measured the speed of light by
Select one:
a. opening a shutter on a lantern on a hilltop and measuring the time taken for light from an assistance's shuttered lantern to return.
b. timing eclipses of Jupiter's satellites, which appeared to

b) timing eclipses of Jupiter's satellites, which appeared to occur later when Earth was farther from Jupiter.

When light passes through a prism of glass, the
Select one:
a. different colors or wavelengths of light are separated in angle by the prism.
b. prism absorbs colors from different parts of the broad beam coming out of the prism, leaving the complementary

a. different colors or wavelengths of light are separated in angle by the prism.

Which one of the following statements is true?
Select one:
a. Visible light takes up only a very small part of the total range of wavelengths in the electromagnetic spectrum.
b. Visible light is not part of the electromagnetic spectrum.
c. Visible light t

a. Visible light takes up only a very small part of the total range of wavelengths in the electromagnetic spectrum.

A blackbody is an idealized object that
Select one:
a. reflects and emits light with the same intensity at all wavelengths.
b. neither reflects nor emits light.
c. reflects no light and emits light in a manner determined by its temperature.
d. both reflec

c. reflects no light and emits light in a manner determined by its temperature.

Why does the Sun look red at sunset?
Select one:
a. The air molecules absorb blue light better than red light, allowing more red light to reach our eyes.
b. The air molecules scatter red light better than blue light, so more red light reaches our eyes.
c.

c. The air molecules scatter blue light better than red light, so only red light arrives to our eyes.

If light from a hot, dense star is viewed through a cool cloud of gas
Select one:
a. the whole spectrum will be reduced in intensity.
b. the spectrum of the star will still be seen unchanged because the gas cloud is cool.
c. only specific wavelengths of l

c. only specific wavelengths of light will be removed from the spectrum.

When electromagnetic radiation (e.g., light) is Doppler-shifted by motion of the source away from the detector the
Select one:
a. measured frequency is higher than the emitted frequency.
b. speed of the radiation is reduced below the emitted speed.
c. det

c. detected wavelength is longer than the emitted wavelength.

Lenses are used in applications like microscopes and telescopes. What does a lens do in these applications?
Select one:
a.
Lenses sort out the entering light by color (or wavelength) and absorb the colors not required for the image.
b.
A lens captures all

d. Light which would not otherwise form an image enters a lens and has its direction changed so that it focuses to form an image.

Which of the following statements correctly describes the refraction of light?
Select one:
a. A light ray reverses its direction of travel after striking a mirror surface.
b. A ray of light spreads after passing through an opening because of the wave natu

d. The path of a ray of light bends as the light enters or leaves a dense transparent medium such as glass.

The light-gathering power of a telescope is related directly to the
Select one:
a. focal length of its primary mirror or lens.
b. area of its primary mirror or lens.
c. image quality of its optics (resolution).
d. ratio of the focal lengths of its primary

b. area of its primary mirror or lens.

By what factor is the amount of light gathered by the 10-m diameter Keck telescope on Mauna Kea, Hawaii, greater than that gathered by the 2.5-m diameter Mount Wilson telescope?
Select one:
a. 256
b. 16
c. 4
d. 2

b. 16

Which of the following types of telescope will suffer from chromatic aberration unless very expensive measures are taken to avoid it?
Select one:
a. radio telescope
b. reflecting telescope
c. Cassegrain telescope
d. refracting telescope

d. refracting telescope

To produce the sharpest images of very distant objects, the best shape for the cross-section of a large astronomical mirror should be
Select one:
a. parabolic
b. elliptical
c. spherical
d. flat

A) Parabolic

At the extreme limit of magnification, the major cause of blurred and unsharp images of objects observed through very large telescopes is
Select one:
a. air turbulence in Earth's atmosphere.
b. the poor optical polish achievable on large mirrors.
c. the p

a. air turbulence in Earth's atmosphere.

The technique used by astronomers to increase the amount of detail that can be seen or photographed through telescopes is
Select one:
a. increased size, where mirrors are made far larger than was possible before, e.g., 8 to 10 meters in diameter and large

c. adaptive optics, where the tilt and shape of mirrors in the telescope are changed many times per second to compensate for atmospheric turbulence.

What is a charge-coupled device (CCD)?
Select one:
a. a very fine grained photographic film which can be "read" electronically
b. an array of electronic sensors which record the charge buildup due to photon absorption
c. an extremely sensitive thermocoupl

b. an array of electronic sensors which record the charge buildup due to photon absorption

Astronomers began to use radio telescopes to investigate the universe
Select one:
a. in the late 1940's, shortly after World War II.
b. during the 1920s.
c. in the early 1960s, with the development of satellites.
d. during the 1980s, with the development

a) in the late 1940's, shortly after WWII

If the unaided human eye is sensitive enough to see about 6000 of the stars in the entire sky, about how many stars can be seen from the North Pole?
a. All 6000 of them every night
b. only half (3000) because the rest are below the horizon all the time
c.

b. only half (3000) because the rest are below the horizon all the time

What basic pattern do stars seem to trace out in our sky if you watch (or photograph) stars near the north celestial pole for a period of several hours?
a. almost straight lines, rising from the horizon towards the zenith
b. spirals, as the stars move whi

c. circles, with the north celestial pole at the center

The two coordinates used by astronomers to define the position of a star in the sky that is applicable anywhere on Earth are
a. azimuth and elevation
b. right ascension and declination
c. horizontal and vertical angles
d. latitude and longitude

b. right ascension and declination

The summer solstice position coordinates are RA = 6h, declination = +23.5�. What are the coordinates of the winter solstice?
a. RA = 18h, declination = +23.5�
b. RA = 0h, declination = 0�
c. RA = 12h, declination = -23.5�
d. RA = 18h, declination = -23.5�

d. RA = 18h, declination = -23.5�

What is the primary cause of Earth's seasons?
a. The orbit of Earth is an ellipse, so Earth is not always at the same distance from
the Sun.
b. Earth's rotation axis tilts with respect to the plane of its orbit around the Sun.
c. Earth's precession axis p

b. Earth's rotation axis tilts with respect to the plane of its orbit around the Sun.

At what time of the year will the shadow of a vertical pole (a sundial) at any site in the northern hemisphere be the shortest?
a. noon, August 5, midsummer
b. noon, December 21, at the beginning of winter
c. noon, June 21, at the beginning of summer

c. noon, June 21, at the beginning of summer

Precession is the
a) accuracy with which numbers are given in astronomy.
b) slow motion of the Earth's rotation axis on the celestial sphere.
c) apparent backward motion of planets on the celestial sphere.
d) daily eastward motion of the Sun around the ce

b) slow motion of the Earth's rotation axis on the celestial sphere.

Which of the following is NOT a consequence of precession:
a) The star that we refer to as the "north star" changes every few thousand years
b) The seasons "shift" in time very slowly (March will feel more like winter in a
few thousand years)
c) The exist

c) The existence of seasons

The phase of the Moon during a lunar eclipse
a) is always full.
b) is always new.
c) is always waning crescent.
d) is always waxing gibbous.

a) is always full.

Suppose tonight is new Moon. You are an astronaut on the side of the Moon facing the Earth. What phase of Earth do you see?
a) You can't see the Earth because it is eclipsed by the Sun.
b) new Earth
c) first quarter Earth
d) full Earth

d) full Earth

If the Moon was third quarter last Saturday, what phase will it be this Saturday? (Remember that it takes about 30 days for the Moon to complete a full revolution)
a) waning crescent
b) waxing gibbous
c) at or very near first quarter
d) at or very near ne

d) at or very near new

If you observe the Moon rising in the east as the Sun is setting in the west, then you know that the phase of the Moon must be
a) new.
b) first quarter.
c) full.
d) third quarter.

c) full

Why don't lunar eclipses happen at every full moon?
a) The Moon's orbit has a 5 degrees tilt with respect to the Earth's orbit around the Sun
b) The Moon's orbit sometimes takes it far enough away that the Earth's shadow has disappeared
c) The Moon's orbi

a) The Moon's orbit has a 5 degrees tilt with respect to the Earth's orbit around the Sun

The Moon goes around the Earth in the same counter-clockwise direction in which the Earth rotates around itself and around the Sun
a) True
b) False

a) True

What would an astronaut on the near side of the Moon see during one month?
a) See the Earth neither rise nor set, but stay nearly fixed at the same position in the skye.
b) See the Earth rotate on its axis once every 24h
c) See the Earth go through phases

d) All of the above

A correct description for the relationship between the period of revolution (P) and the distance of a planet to the Sun (A) would be
a) P2 is proportional to A3
b) P is proportional to A2.
c) P is proportional to A.
d) P does not correlate at all with A.

a) P2 is proportional to A3

__________ was the first person to truly solve the problem of accurately describing planetary motion.
a) Copernicus.
b) Tycho.
c) Kepler.
d) Galileo.

c) Kepler.

Which situation does NOT correspond to having a force acting on the object:
a) a car traveling with constant speed on a straight road.
b) a car traveling with constant speed around a bend.
c) a planet traveling in its orbit around the Sun.
d) a car slowin

a) a car traveling with constant speed on a straight road.

You are an astronaut taking a spacewalk to fix your spacecraft. You are working with a hammer when your lifeline breaks and you start drifting away. To return safely to your spacecraft you should
a) throw the hammer at the spaceship
b) throw the hammer in

b) throw the hammer in the direction opposite to the space ship.

Which fundamental misconception(s) made Ptolemy's geocentric model very complicated and prevented it from adequately describing the movements of bodies in the Solar System?
I) The Sun is at the center of the universe. II) All heavenly bodies move in combi

d) II and III.

Observations of Venus are at odds with the geocentric model because in this model
a. Venus would not be expected to significantly change in size
b. Venus would never appear in "full" phase
c. Venus would never show retrograde motion
d. Venus would not be

b. Venus would never appear in "full" phase

Galileo's discovery of the moons of Jupiter was shocking because it showed those who believed Earth to be at the center of the Universe that
a. A planet could have more than one moon b. Earth was unusual to have only one moon c. Gravity could hold a moon

e. Objects could move around a moving object that wasn't Earth

If the radius of the Earth was doubled, your weight would be
a) less than half your current weight
b) half your current weight
c) the same
d) double your current weight

a) less than half your current weight

When light passes through a prism of glass, the
a) different colors are caused by multiple reflections in the prism and interference
between the resulting beams.
b) different colors or wavelengths of light are separated in angle by the prism.
c) prism abs

b) different colors or wavelengths of light are separated in angle by the prism.

Which is the correct reasoning for why a x-ray telescope located in Antarctica that is to
be used to look for evidence of black holes in the centers of galaxies should not get
funded?
A)There is no way to detect the presence of a black hole.
B) Only half

D) X-rays don't penetrate Earth's atmosphere.

The first reliable method developed to measure the speed of light involved
A) careful observation of the eclipses of the moons of Jupiter at different times in Jupiter's orbit.
B) observing the opening and closing of shutters on lanterns on hilltops separ

A) careful observation of the eclipses of the moons of Jupiter at different times in Jupiter's orbit.

Gamma rays and visible light are
A) different because gamma rays are made up of particles, whereas light is made up of waves.
B) the same thing except that gamma rays have a smaller frequency than visible light.
C) the same thing except that gamma rays ha

C) the same thing except that gamma rays have a larger frequency than visible light.

As a new star evolves from a warm gas to a very hot body, the peak wavelength of its spectrum of electromagnetic radiation should
A) change from the ultraviolet to the visible range.
B) change from the infrared to the visible wavelengths.
C) increase from

B) change from the infrared to the visible wavelengths.

A blackbody is an idealized object that
A) reflects and emits light with the same intensity at all wavelengths.
B) neither reflects nor emits light.
C) both reflects and emits light in a manner determined by its temperature.
D) reflects no light and emits

D) reflects no light and emits light in a manner determined by its temperature.

The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a tube in a laboratory or a gas cloud in space) are caused by
A) the vibrations of the electrons within the atom.
B) an electron dropping into the nucleus and causing changes in

C) electrons jumping to lower energy levels, losing energy as they do so.

The hot, dense gas existing in the Sun emits energy
A) at all wavelengths uniformly.
B) at all wavelengths, with a peak at one particular wavelength (color).
C) only at certain wavelengths and no others.
D) mostly at the longest and shortest wavelengths,

B) at all wavelengths, with a peak at one particular wavelength (color).

The reason the primary mirror of an astronomical telescope is often polished to a parabolic shape is
A) to avoid the chromatic aberration that would be produced by an equivalent spherical mirror.
B) that it is lighter and easier to mount in a telescope.
C

D) to avoid spherical aberration.

The future EELT (European Extremely Large Telescope) will have a diameter of 40m. How many times larger will be the light gathering-power of the EELT compared to one of the Keck telescopes (which has a diameter 10 m) ?
A) 2 times larger
B) 4 times larger

D) 16 times larger

What are the coordinates of San Luis Obispo?

c) 35.3� N ; 120.7� W