question

The number of degrees in a full circle is

answer

360

question

How many arcseconds are there in a full circle?

answer

360 x 3600

question

In angular measurements used in astronomy, how many right angles are there in a full circle?

answer

four

question

One arcsecond is equal to

answer

1/3600 degree

question

One arcminute is equal to

answer

1/60 degree.

question

On a particular night, Jupiter subtends an angle of 42 arcseconds as seen from Earth. This angle is

answer

roughly three-quarters of an arcminute.

question

Astronauts on the Moon look back at Earth, a distance of about 400,000 km away. If the cities of Washington, D.C., and New York are separated by about 300 km, what will be the angle between them when viewed from the Moon?

answer

2.5 arcminutes

question

Two very bright fireworks are exploded at the same time during the July 4 celebrations, one in New York, the other in Los Angeles (4000 km apart). How far apart in angle will these flashes appear to astronauts on the Moon, who are 400,000 km from Earth?

answer

34.4 arcminutes

question

At what distance would a friend have to hold a dime (about 1 cm diameter) for it to subtend an angle of 2 arcseconds?

answer

1 km

question

The number five hundred thousand is written in powers-of-ten notation as

answer

5 × 105.

question

10^5 × 10^8 =

answer

10^13

question

One billionth divided by one millionth is equal to

answer

10^-3

question

By what approximate factor in powers-of-ten notation is a human being (height about 2 m) larger than the nucleus of a hydrogen atom, or proton (diameter about 10^-15 m)?

answer

2 × 10^15

question

One astronomical unit, or one AU is defined as the

answer

mean distance between the Sun and Earth.

question

A light-year is a measure of

answer

distance.

question

If you were able to travel out into space until the angular distance between Earth and the Sun was 1 second of arc, how far would you be from the Sun? (Assume that Earth-Sun line is at right angles to your line of sight.)

answer

1 pc

question

The distance to the star τ Scorpii has been measured as 230 pc. Expressed in light-years, this is approximately

answer

750 ly.

question

The time taken for light to travel to Earth from a galaxy that is 10 Mpc away is

answer

3.26 × 10^7 years.

question

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

answer

km, AU, ly, pc

question

A star rises at 8 P.M., moves across the sky (crossing high overhead), and then sets at

answer

8 A.M.

question

The phrase "diurnal motion" refers to the

answer

gradual motion of the constellations from east to west across the sky each night, resulting in different constellations being visible at 4 A.M. than at 10 P.M. on any given night.

question

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?

answer

circles, with the north celestial pole at the center

question

With respect to the stars, the rotation of Earth carries you toward the

answer

east.

question

Which of the following lines or points is always directly over your head, no matter where on Earth you go?

answer

zenith

question

Diurnal motion of objects in the sky is caused by the

answer

rotation of Earth on its axis.

question

The nightly motion of objects across our the sky is caused by the

answer

rotation of Earth on its axis.

question

The ecliptic is defined as the

answer

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

question

The ecliptic crosses the celestial equator at

answer

two points, known as equinoxes.

question

Earth would not have seasons if

answer

its axis of rotation were perpendicular to its orbital plane.

question

Summertime in the northern hemisphere is when

answer

more direct sunlight shines on this hemisphere.

question

It is warmer in summer than winter because

answer

the Sun is higher in the sky and the days are longer.

question

One required condition for seasons to occur is that a planet's

answer

spin axis be tilted with respect to the perpendicular to its orbital plane.

question

The equinoxes are located at the intersections of the

answer

ecliptic and the celestial equator.

question

When the Sun is at one of the equinoxes,

answer

day and night are of equal length everywhere on Earth.

question

If you observe from a location north of the equator the Sun's position on the horizon as it rises each morning throughout the year you will find that

answer

the rising position moves progressively northward from December through June.

question

The Sun rises due east in the sky when viewed from any site

answer

on Earth only on the first day of spring and the first day of fall.

question

The Arctic Circle is at a latitude of

answer

66.5° N.

question

The Arctic Circle is defined as a line on Earth where the Sun

answer

can be seen for 24 hours on at least one day of the year.

question

Precession is

answer

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

question

What is the significance of Polaris, the North Star?

answer

Polaris is almost on the curve traced out by the rotation axis as a result of the precession of the rotation direction.

question

The position in Earth's orbit around the Sun which presently corresponds to Winter Solstice will instead correspond to Summer Solstice in about

answer

13,000 years.

question

Precession of Earth's axis of rotation is caused by

answer

the gravitational pull of the Moon and the Sun on the equatorial bulge of Earth.

question

The reason for the slow movement of the vernal equinox through our sky against the background stars over long periods of time is the

answer

precession of the spin axis of Earth.

question

The precessional motion of the north celestial pole of Earth over a period of 26,000 years is a circle of 47° diameter in the northern sky. The equivalent motion of the south celestial pole is

answer

a circle of 47° diameter, covered in 26,000 years.

question

Which of the following is the correct sequence of appearances of Moon phases in the sky?

answer

waxing crescent, first quarter, waxing gibbous, full moon

question

Why do we see different phases of the Moon?

answer

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

question

A full moon is always at its highest in our sky at

answer

midnight.

question

In its orbit around Earth, the Moon

answer

always keeps the same side toward Earth.

question

Earth's shadow falling on the Moon is the reason we see

answer

lunar eclipses.

question

What is the one major difference between the Sun and the Moon in our sky?

answer

The Sun emits light while the Moon merely reflects it.

question

At what approximate time does a full moon rise?

answer

sunset

question

A full moon always occurs

answer

when the Moon is farther from the Sun than is Earth.

question

The phase of the Moon when the Sun and Moon are separated by 6 hours of right ascension is always

answer

either first or third quarter.

question

When the Sun and Moon are separated by 12 hours of right ascension, the phase of the Moon is always

answer

full moon.

question

The correct order of "appearance" of the following "actors" on the "stage" of scientific discovery is

answer

Ptolemy, Copernicus, Kepler, Newton, Einstein.

question

The word planet is derived from a Greek term meaning

answer

wanderer.

question

When observing planetary motions from Earth, the phrase "retrograde motion" refers to

answer

a slow westward motion of the planet from night to night against the background stars.

question

Retrograde motion of a planet against the background stars is always

answer

movement from east to west.

question

The epicycle in the Greek planetary model is

answer

a small circle through which the planet moves as the center of this circle orbits Earth.

question

In the geocentric model for the solar system developed by Ptolemy, to what does the word "deferent" refer?

answer

the large circle around Earth through which the center of a smaller circle moves while the planet moves around the smaller circle

question

When Venus is at inferior conjunction,

answer

it is at its smallest distance from Earth.

question

When Venus is at superior conjunction,

answer

it is at its greatest distance from Earth.

question

n which direction is Venus moving when it is at greatest elongation?

answer

directly toward or away from Earth

question

When Saturn is at its farthest distance from Earth, it is at

answer

conjunction.

question

Galileo's early observations of the sky with his newly made telescope included the

answer

fact that Venus showed phases similar to those of the Moon.

question

How many moons of Jupiter were seen by Galileo?

answer

4

question

Which of the following statements correctly states the significance of Galileo's observation that Jupiter has satellites (moons)?

answer

It showed that bodies can orbit an object other than Earth.

question

As Venus orbits the Sun, by what factor, as viewed from Earth, does its angular size change from smallest to largest?

answer

5.8 ×

question

Which of the following statements correctly states the significance of Galileo's observation that Venus shows phases?

answer

The phases were correlated with angular size in a way that supported the heliocentric theory.

question

In the geocentric model of the solar system, which one of the following phases of Venus should be visible from Earth?

answer

new

question

A body whose velocity is constant

answer

has zero acceleration.

question

Which path would a planet (like Earth) take if the force of gravity from the Sun were to be suddenly removed?

answer

The planet would move in a straight line tangential to its present orbit.

question

Newton's law of universal gravitation is so named because it

answer

holds for all objects in the universe.

question

Suppose that an object is discovered moving around the Sun once every 120 years. Which of the following paths is a possible orbit for this object?

answer

ellipse

question

Spring tides occur

answer

twice a month, at full and new moon.

question

The highest of all tides on Earth's oceans occur at

answer

full or new moon, at times when Moon and Sun are closest to Earth.

question

Neap tides occur

answer

twice a month, at first and third quarter moon.

question

Does the Sun or the Moon have a greater effect in causing the tides on Earth?

answer

The Moon, because it has a larger difference between pulling on the near side and pulling on the far side of Earth

question

How many "tidal bulges" are there on Earth, due to the Moon's gravitational pull?

answer

two, one facing (almost) directly toward the Moon and one facing (almost) directly away from the Moon

question

What are spring tides?

answer

High tides that are significantly higher than the average high tide

question

The reason the Moon always keeps one face toward Earth is that

answer

gravitational forces from Earth act on the tidal bulge of the Moon.

question

In 1675, Rømer measured the speed of light by

answer

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

question

The average distance of Pluto from the Sun is 40 AU. How long does it take for light to travel across the solar system from one side of Pluto's orbit to the other?

answer

11 hrs

question

Radio waves travel through space at what speed?

answer

at the speed of light, 3 × 108 m/s

question

When light passes through a prism of glass, the

answer

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

question

Around 1670, Isaac Newton performed a crucial experiment on the nature of light when he

answer

demonstrated that the colors that make up white light are intrinsic, not produced by the glass through which the light passes.

question

Visible light occupies which position in the whole electromagnetic spectrum?

answer

between infrared and ultraviolet

question

In terms of wavelengths, gamma rays are

answer

the shortest-wavelength electromagnetic waves.

question

What is the wavelength of electromagnetic radiation whose frequency is 106 cycles per second (106 Hz or 1000 kHz, the frequency of ordinary AM radio)?

answer

300 m

question

On the absolute scale of temperature (in kelvins), the zero of the scale corresponds to the

answer

temperature at which motions of atoms and molecules essentially cease.

question

A typical but very cool star might have a temperature of 3100°C. On the Kelvin scale, this is about

answer

3373 K.

question

Wien's law, relating the peak wavelength λmax of light emitted by a dense object to its temperature T , can be represented by

answer

λmax T = constant.

question

We plot the intensity of the radiation emitted from a solid object at a certain temperature versus its wavelength. As we increase the temperature, the wavelength at which the spectrum peaks becomes shorter and shorter. This is an illustration of

answer

Wien's Displacement Law.

question

We plot the intensity of the radiation emitted from a solid object at a certain temperature versus its wavelength. As we increase the temperature, the total amount of energy emitted all across the spectrum increases as the fourth power of the temperature. This is an illustration of

answer

the Stefan-Boltzmann Law.

question

Cepheid-variable stars pulsate regularly in size. During the contraction part of the cycle, when the star's temperature is increasing, the peak wavelength of the emitted radiation

answer

shifts from the visible to the UV part of the spectrum.

question

The total energy flux F of radiation emitted per unit area by a blackbody (e.g., star) is related to its temperature T and a constant σ by which equation?

answer

F = σT 4

question

A piece of iron is heated from 400 to 800 K (127 to 527°C). By what factor will the total energy per second emitted by this iron increase?

answer

16

question

Pieces of metal are heated by varying amounts in a flame. The hottest of these is the one that shows which color most prominently?

answer

blue

question

What changes would you expect to see in the resulting spectrum of emitted light from a piece of metal when it is heated slowly in an intense flame from 500 K to 1500 K?

answer

The intensity of radiation would increase and its color would change from red through white to blue.

question

The spectrum of sunlight, when spread out by a spectrograph, has what characteristic appearance?

answer

continuous band of color, crossed by innumerable dark absorption lines

question

The dark absorption lines in the solar spectrum are caused by absorption

answer

of sunlight in a cooler layer of gas overlying the hot solar surface.

question

The star Betelgeuse has a lower surface temperature than the Sun; therefore (with IR = infrared and UV = ultraviolet)

answer

Betelgeuse emits less IR and less UV flux than the Sun.

question

When a rod of metal is heated intensely, its predominant color

answer

changes from red, through orange to white, and then to blue.

question

The Sun's surface has a temperature of 5800 K. What will be the peak wavelength of the spectrum of a star that emits twice the Sun's flux of energy?

answer

2.5 × 10^-7 m

question

Atoms in a hot, low-density gas (e.g., in a laboratory-type spectral source) emit a spectrum that is

answer

a series of specific colors, unique to the type of atom in the tube, but fixed in position even when the gas temperature changes.

question

Why is the sky blue?

answer

The air molecules scatter blue light better than red light, so more blue light reaches our eyes.

question

The setting Sun appears red because

answer

its light is scattered by a thicker layer of air than during the day.

question

The physical structure of an atom is

answer

negatively charged electrons moving around a very small but massive, positively charged core.

question

In a simple atom the electrons making transitions between the outermost energy levels and the innermost energy levels give rise to photons with

answer

the highest energies.

question

Electrons in atoms

answer

occupy levels whose energies are fixed.

question

The spectrum of a star shows an equivalent set of dark absorption lines to those of the Sun, but with one exception: Every line appears at a slightly longer wavelength, shifted toward the red end of the spectrum. What conclusion can be drawn from this observation?

answer

The star is moving rapidly away from Earth.

question

When electromagnetic radiation (e.g., light) is Doppler-shifted by motion of the source away from the detector the

answer

detected wavelength is longer than the emitted wavelength.

question

When an object is moving toward you the visible radiation which it emits is Doppler shifted toward the

answer

ultraviolet

question

An astronomer photographs the spectrum of an object and finds a spectral line at 499 nm wavelength. In the laboratory, this spectral line occurs at 500 nm. According to the Doppler effect, this object is moving

answer

toward Earth at 1/500 the speed of light.

question

Compared to its speed in a vacuum (or in space), the speed of light in glass is

answer

less

question

As light passes from air into a dense but transparent material it

answer

slows down

question

Lenses are used in applications like microscopes and telescopes. What does a lens do in these applications?

answer

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

question

When light passes from air into glass it is refracted. This means that

answer

the wave slows down.

question

Refraction is the

answer

bending of light as it enters a transparent material.

question

Which type of telescope uses a lens as the main optical element?

answer

refracting telescope

question

The main reason for building large optical telescopes on Earth's surface is

answer

to collect more light from faint objects.

question

A refracting telescope has an objective lens of focal length 80 cm, a diameter of 10 cm, and an eyepiece of focal length 5 cm and diameter 1 cm. What is the magnifying power of this telescope?

answer

16x

question

A particular reflecting telescope has an objective mirror with a focal length of 1.2 m and an eyepiece lens of focal length 6 mm. What is the magnifying power of this telescope?

answer

200x

question

Chromatic aberration occurs in a refracting telescope when

answer

all colors of light do not come to the same focal point.

question

How can you increase the magnification of a refracting telescope without decreasing the light gathering power?

answer

decrease the focal length of the eyepiece

question

At the mirror of a reflecting telescope, the light reflects from a coated surface rather than refracting through a lens. This eliminates

answer

chromatic aberration.

question

It is difficult to improve the angular resolution of optical telescopes located on the surface of Earth beyond a certain limit because

answer

air turbulence distorts the star images more than does the telescope optics.

question

One major difference between radio waves and light is that

answer

radio waves have lower frequencies.

question

A radio telescope

answer

is very similar to a reflecting optical telescope.

question

The correct sequence of planets in our solar system from the Sun outward is

answer

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

question

In our solar system, which of the following planets is not a member of the terrestrial group?

answer

Jupiter

question

In our solar system, which of the following planets is not a member of the Jovian group?

answer

Mars

question

Orbital eccentricity is a number that describes the

answer

shape of the orbital ellipse.

question

The planet whose orbit is inclined at the greatest angle to the plane of the ecliptic is

answer

Mercury.

question

A perfect circle is an ellipse with an eccentricity of

answer

zero.

question

The best way to measure the mass of a planet is to measure the

answer

gravitational pull of the planet on an orbiting satellite or a nearby spacecraft.

question

A curious fact about the structure of the planet Jupiter, compared to that of Earth, is that it has

answer

much greater mass but much lower average density.

question

Viewed from a position above the north pole of the Sun, the directions of the motions of the planets in their orbits are

answer

all counterclockwise.

question

Determination of the chemical composition of the atmospheres of the planets is carried out most effectively by what type of study?

answer

spectroscopy—the measurement of absorption features in their spectra

question

Comets are typically

answer

chunks of ice that begin to vaporize if they pass close to the Sun.

question

In general, large bodies in the solar system show less evidence of cratering than do small bodies. Why should we expect this correlation?

answer

Large bodies cool more slowly and are more likely to retain internal heat and be geologically active, capable of resurfacing the planet and obliterating craters.

question

In general, small bodies in the solar system are less likely than large bodies to possess a planet-wide magnetic field. Why should we expect size and magnetism to be correlated?

answer

A small body cools more rapidly and is less likely to possess a molten, liquid interior — one requirement for planet-wide magnetism.

question

One distinct difference between Earth and its neighboring planets, Venus and Mars, is the presence of

answer

liquid water on its surface and water molecules chemically locked into rocks.

question

The albedo of a planet is the fraction of energy that is

answer

reflected by the whole planet, including atmosphere and surface.

question

The greenhouse effect is the

answer

absorption by atmospheric gases of infrared radiation emitted by a planet that has been heated by solar visible and ultraviolet radiation.

question

Earth has an average density of

answer

5.5 times that of water.

question

"Chemical differentiation" in planetary sciences refers to

answer

the sinking of heavier elements toward the center of a planet and the floating of lighter elements toward the surface.

question

The mantle of Earth is composed of

answer

rock.

question

What is the basic structure of Earth's interior?

answer

solid iron inner core, molten iron outer core, rocky mantle, lighter rocky crust

question

Earth's magnetic field is caused by

answer

electric currents flowing in the molten core.

question

The auroral display of northern and southern lights in the atmosphere is caused by

answer

solar wind electrons hitting the high atmosphere after being accelerated by the magnetosphere.

question

Photosynthesis is a chemical process which takes place in green plants. What is its effect on our atmosphere?

answer

Photosynthesis consumes carbon dioxide from our atmosphere and produces oxygen.

question

Which is the most abundant gas in Earth's atmosphere?

answer

nitrogen

question

Why did Earth's earliest atmosphere, composed primarily of hydrogen, not last long?

answer

Hydrogen is a very light gas, and it soon escaped into space.

question

The major layers of Earth's atmosphere from the surface upward in correct order are

answer

troposphere, stratosphere, mesosphere, thermosphere.

question

In which layer of Earth's atmosphere does all weather occur?

answer

troposphere

question

In which layer of Earth's atmosphere is the ozone layer located?

answer

stratosphere

question

In its orbit around Earth, the Moon

answer

always keeps the same side toward Earth.

question

How long is a "lunar day," or the time between two successive sunrises or sunsets on the Moon?

answer

about 1 month

question

Astronauts at a Moon base visible from Earth will NOT see

answer

Earthrise or Earthset.

question

The Moon has

answer

no measurable atmosphere or liquid water.

question

Maria on the Moon exist

answer

only on Earth-facing side of the Moon.

question

Why are the lunar maria concentrated almost entirely on the near side of the Moon?

answer

The crust is thicker on the far side of the Moon, restricting massive lava flows after asteroid impact.

question

The mountains on the Moon were mostly caused by

answer

impacts from meteoroids from outer space.

question

One effect of the ocean water's tidal drag on Earth is to

answer

slow down Earth's spin rate.

question

Because of the tides on Earth's oceans, the Moon is

answer

spiraling outward away from Earth.

question

Which of the following is believed to be the correct explanation for the origin of the Moon?

answer

Earth was struck by a large planetesima, which caused material to be ejected. This material coalesced to form the Moon.

question

The existence of stars composed almost entirely of neutrons was first predicted by

answer

Fritz Zwicky and Walter Baade, in 1933.

question

A pulsar is

answer

a rapidly rotating neutron star, emitting beams of radio radiation and in some cases X-rays and visible light

question

The pulsation periods of most pulsars are in the range

answer

of 1/1000 second and a few seconds.

question

The very strong magnetic field of a neutron star is created by

answer

the collapse of a star, which significantly intensifies the original weak magnetic field of the star.

question

The strength of the magnetic field around a typical neutron star is

answer

about a trillion (1012) gauss, or about a million times stronger than the strongest magnetic fields ever produced in laboratories on Earth.

question

The periods of most pulsars

answer

increase with time.

question

Synchrotron radiation is emitted whenever

answer

charged particles are forced to move along curved paths within a magnetic field.

question

Glitches are occasionally observed by astronomers studying pulsars. What are these glitches?

answer

sudden increases in rotation rate

question

Astronomers believe neutron stars may have atmospheres. What form of evidence do we have for this?

answer

dips in the X-ray spectrum emitted by the neutron star suggesting that these wavelength ranges are absorbed by an atmosphere

question

The Black Widow pulsar is unusual because it appears to

answer

be eating away at its companion star.

question

The age of the solar system has been dated rather precisely to 4.56 billion years. What method was used to determine this number?

answer

determining the age of meteorites by radioactive dating

question

The most common elements in the universe are

answer

hydrogen, smaller quantities of helium, and very small quantities of heavier elements.

question

Together, hydrogen and helium account for what percentage of the total mass of all matter in the universe?

answer

98%

question

What fraction of the mass of the universe is in the form of atoms other than hydrogen and helium?

answer

2%

question

Where in the universe are heavy elements with masses greater than that of helium being produced at this time?

answer

central cores of stars

question

What was the form of the material from which the solar system formed?

answer

a nebula made mostly of hydrogen and helium gas, but enriched in heavier elements from supernova explosions

question

The temperature began to rise at the center of the solar nebula because

answer

the nebula was contracting, increasing the speed of motion of the atoms.

question

Which of the following statements is an example of Kelvin-Helmholtz contraction?

answer

A contraction of a dense cloud of gas slowly gets hotter due to the release of gravitational energy.

question

Which one of the following is not an example of the conservation of angular momentum?

answer

The Moon always keeps one face pointed toward Earth.

question

The most probable time sequence for the solar system's formation was that the

answer

Sun contracted first as a gas ball, and the planets and moons formed shortly afterward by accretion and condensation.

question

The process of accretion in planetary formation is the

answer

slow accumulation of solid particles by gravity and collision into larger, solid objects.

question

The formation of terrestrial-type planets around a star is most likely to have occurred by what process?

answer

accretion, or slow accumulation of smaller particles by mutual gravitational attraction

question

What is the process of chemical differentiation?

answer

the sinking of heavy material to the center of a planet or other object and the rising of lighter material toward the surface

question

The reason most of the terrestrial planets have dense, iron cores is because

answer

terrestrial planets were initially molten or partially molten, and the iron sank to the center.

question

A Tauri wind is

answer

a rapid expulsion of the tenuous outer layers of a young star.

question

The Oort cloud is

answer

a spherical solar system halo of icy objects far beyond the orbit of Pluto.

question

Astrometry is the very precise measurement of

answer

a star's position in the sky (e.g., to measure its motion).

question

So far, what is the typical mass of the majority of extrasolar planets discovered?

answer

between the the mass of Saturn and a few times the mass of Jupiter

question

What is "special" about the special theory of relativity?

answer

It deals only with objects moving in a straight line at constant speed.

question

In order to use the theory of special relativity to describe an object's motion, the object must be moving

answer

at a constant speed in a straight line; how fast it is moving is not important.

question

Einstein's theory of special relativity contains some very strange ideas such as time dilation (moving clocks run slow), length contraction (moving lengths are shorter), and lack of absolute simultaneity. What are these ideas based upon?

answer

The speed of light is the same for all observers in all reference frames.

question

Suppose you are in a jet airliner traveling at a constant speed of 400 km/h in a constant direction. All windows are blocked so you cannot see outside, and there are no vibrations from the engines. What experiment can you do to determine that you are in fact moving?

answer

None. All experiments will give the same results as when you are at rest on the ground.

question

You are flying your spacecraft on a parallel course with another spacecraft and at the same speed. You are both moving past Earth at an appreciable fraction of the speed of light. Which one of the following statements correctly describes the relationship between your clock and the clock in the other spacecraft?

answer

You will see the clock in the other spacecraft running at the same rate as yours.

question

Two rocket ships are traveling past Earth at 90% of the speed of light in opposite directions (i.e., they are approaching each other). One turns on a searchlight beam, which is seen by scientists aboard the second spaceship. What speed do the scientists measure for this light? (c = speed of light in a vacuum)

answer

c

question

If you see an object moving past you at 90% of the speed of light, you will measure the length of this object to be

answer

shorter than if it were at rest.

question

Einstein's principle of equivalence in his general theory of relativity asserts that

answer

being at rest in a gravitational field is equivalent to being in an upwardly accelerated frame of reference in a gravity-free environment.

question

According to general relativity, why does Earth orbit the Sun?

answer

Space around the Sun is curved and Earth follows this curved space.

question

Black holes are so named because

answer

no light or any other electromagnetic radiation can escape from inside them.

Astronomy Mid Term – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards