other astro terms

94 terms by mcguiregillan 

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Which of the following represents a case in which you are not accelerating?

Driving in a straight line at 60 miles per hour

Suppose you drop a 10-pound weight and a 5-pound weight on the Moon, both from the same height at the same time. What will happen?

Both will hit the ground at the same time.

Why are astronauts weightless in the Space Station?

Because the Space Station is constantly in free-fall around the Earth

A net force acting on an object will always cause a change in the object's _________.

momentum

Suppose you are in an elevator that is traveling upward at constant speed. How does your weight compare to your normal weight on the ground?

It is the same.

The planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that _________.

a force is acting on the planets

Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen?

The Sun would rotate faster than it does now.

Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight?

The ball's gravitational potential energy is greatest at the instant when the ball is at its highes

Suppose you heat an oven to 400°F and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven?

The water can transfer heat to your arm more quickly than the air.

Which of the following scenarios involves energy that we would typically calculate with Einstein's formula E=mc2?

A small amount of the hydrogen in of a nuclear bomb becomes energy as fusion converts the hydrogen to helium.

A rock held above the ground has potential energy. As the rock falls, this potential energy is converted to kinetic energy. Finally, the rock hits the ground and stays there. What has happened to the energy?

The energy goes to producing sound and to heating the ground, rock, and surrounding air.

Suppose that the Sun shrank in size but that its mass remained the same. What would happen to the orbit of the Earth?

Earth's orbit would be unaffected.

Imagine another solar system, with a star of the same mass as the Sun. Suppose a planet with a mass twice that of Earth (2MEarth) orbits at a distance of 1 AU from the star. What is the orbital period of this planet?

1 yr

Imagine another solar system, with a star more massive than the Sun. Suppose a planet with the same mass as Earth orbits at a distance of 1 AU from the star. How would the planet's year (orbital period) compare to Earth's year?

The planet's year would be shorter than Earth's.

Newton showed that Kepler's laws are _________.

natural consequences of the law of universal gravitation

Each of the following lists two facts. Which pair of facts can be used with Newton's version of Kepler's third law to determine the mass of the Sun?

Earth is 150 million km from the Sun and orbits the Sun in one year.

When space probe Voyager 2 passed by Saturn, its speed increased (but not due to firing its engines). What must have happened?

Saturn must have lost a very tiny bit of its orbital energy.

Suppose that a lone asteroid happens to be passing Jupiter on an unbound orbit (well above Jupiter's atmosphere and far from all of Jupiter's moons.) Which of the following statements would be true?

The asteroid's orbit around Jupiter would not change, and it would go out on the same unbound orbit that it came in on.

Which of the following best describes the origin of ocean tides on Earth?

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the Earth.

At which lunar phase(s) are tides most pronounced (for example, the highest high tides)?

Both new and full moons

Which of the following best explains why the Moon's orbital period and rotation period are the same?

The Moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period.

Suppose the Moon's orbit were unchanged, but it rotated faster (meaning it did not have synchronous rotation). Which of the following would be true?

We would no longer always see nearly the same face of the Moon.

Which of the following has your "cosmic address" in the correct order?

ou, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

Using the ideas discussed in your textbook, in what sense are we "star stuff"?

Nearly every atom from which we are made was once inside of a star.

How are galaxies important to our existence?

Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

When we look at an object that is 1,000 light-years away we see it _________.

as it was 1,000 years ago

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________.

we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?

The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.

If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?

Several thousand years

The total number of stars in the observable universe is about _________.

the same as the number of grains of sand on all the beaches on Earth

Where is our solar system located within the Milky Way Galaxy?

Roughly halfway between the center and the edge of the visible disk of the galaxy

If we imagine the history of the universe compressed into one year, dinosaurs became extinct _________.

yesterday morning

Relative to the age of the universe, how old is our solar system?

It is about one-third the age of the universe.

How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?

Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.

Why do the patterns of the stars in our sky look the same from year to year?

Because the stars in the constellations are so far away.

Astronomers infer that the universe is expanding because distant galaxies all appear to _________.

be moving away from us, with more distant ones moving faster

Which statement about motion in the universe is not true?

The mysterious dark matter is the fastest-moving material in the universe.

When did humans learn that the Earth is not the center of the universe?

Within the past 500 years

Which of the following statements about the celestial sphere is NOT true?

The "celestial sphere" is another name for our universe.

The Andromeda Galaxy is faintly visible to the naked eye in the constellation Andromeda. Suppose instead it were located in the same direction in space as the center of the Milky Way Galaxy (but still at its current distance). How would it appear to the eye in that case?

We could not see it at all.

An angle of 1 arcsecond is _________.

less than the thickness of a human hair held at arm's length

When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________.

higher in the sky

Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at _________.

latitude 40 degrees south

Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?

To the right of Polaris; that is, 90 degrees counterclockwise from its current position

In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________.

our evening view of space depends on where Earth is located in its orbit around the Sun

The Sun's path, as viewed from the equator, is highest in the sky on _________.

the spring and fall equinoxes

Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true?

The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now.

If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth's rotation period and axis tilt were unchanged, then _________.

the four seasons would each be twice as long as they are now

How does Earth's varying distance from the Sun affect our seasons?

It doesn't --- Earth's orbital distance plays no significant role in the seasons.

Suppose you live in the United States and you see a crescent moon in your evening sky tonight. What will a friend in South America see tonight?

Your friend will also see a crescent moon.

Suppose it is full Moon. What phase of Earth would someone on the Moon see at this time?

new Earth

It's 6 am and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase?

third quarter

You observe a full Moon rising at sunset. What will you see at midnight?

A full moon high in the sky

All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon?

The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.

For most of history, the lack of observable stellar parallax was interpreted to mean that _________.

Earth is stationary at the center of the universe

During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?

Earth is catching up with and passing by Mars in their respective orbits.

Suppose you see a photo showing Jupiter half in sunlight and half in shadow (that is, a first quarter Jupiter). This photo might have been taken by _________.

the Galileo spacecraft that orbited Jupiter in the 1990s

Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use?

6,000 joules

Which of the following statements is true of green grass?

It absorbs red light and reflects green light.

Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true?

The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second.

Gamma rays have a very small ______.

wl

Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?

1 meter

Which of the following best describes why we say that light is an electromagnetic wave?

The passage of a light wave can cause electrically charged particles to move up and down.

Which of the following statements about X rays and radio waves is not true?

X rays travel through space faster than radio waves.

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons

Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would occur as you heated the liquid oxygen to high temperature?

It would evaporate into a gas, then the molecules would dissociate into individual oxygen atoms, then the atoms would become increasingly ionized as you continued to raise the temperature.

Consider an atom of oxygen in which the nucleus contains 8 protons and 8 neutrons. If it is doubly ionized, what is the charge of the oxygen ion and how many electrons remain in the ion?

Charge = +2; number of remaining electrons = 6.

Which of the following statements about electrons is not true?

Electrons orbit the nucleus rather like planets orbiting the Sun.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

he cloud is cool and lies between you and a hot star.n

no object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close approximation to a thermal radiation spectrum?

a hot, thin (low-density, nearly transparent) gas

Which of the following statements about thermal radiation is always true?

A hot object emits more radiation per unit surface area than a cool object.

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color

Correct Answer:

Its surface is cooler than the surface of the Sun.

The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun?

Correct Answer:

The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the red light that is present in the Sun's spectrum.

All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays?

The temperature of the corona's gas is some 1 to 2 million Kelvin.

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

The star is moving toward us.

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Star X is moving away from us faster than Star Y.

If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?

The planet is rotating.

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

The total amount of light in the spectrum tells us the star's radius.

Suppose that two stars are identical in every way - for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth - except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?

The faster rotating star has wider spectral lines than the slower rotating star

Suppose you have two small photographs of the Moon. Although both look the same at small size, when you blow them up to poster size one of them still looks sharp while the other one becomes fuzzy (grainy) looking. Which of the following statements is true?

The one that still looks sharp at large size has better (smaller) angular resolution than the one that looks fuzzy.

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?

the photo will seem to show only one star rather than two.

Suppose you point your telescope at a distant object. Which of the following is not an advantage of taking a photograph of the object through the telescope as compared to just looking at the object through the telescope?

the photograph will have far better angular resolution than you can see with your eye.

Which of the following best describes the principle advantage of CCDs over photographic film?

CCDs capture a much higher percentage of the incoming photons than film.

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

the 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.

Which of the following best describes the development of astronomical telescopes over the past 65 years?

The world's most powerful telescope remained the same for most of this period, but in the past 20 years many new and more powerful telescopes have been built.

Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?

Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light.

Which of the following is not a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry climates?

The thin air on mountaintops makes the glass in telescope mirrors less susceptible to warping.

the stars in our sky twinkle in brightness and color because of ______.

turbulence in the Earth's atmosphere

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?

It is closer to the stars.

The Chandra X-ray Observatory must operate in space because:

X rays do not penetrate Earth's atmosphere.

Which of the following telescopes would benefit most from adaptive optics?

The Keck I telescope on Mauna Kea.

Consider two future observatories in space. Observatory X consists of a single 50-meter telescope. Observatory Y is an interferometer consisting of five 10-meter telescopes, spread out over a region 100 meters across. Which observatory can detect dimmer stars, and which one can see more detail in its images? (Assume all else is equal, such as quality of optics, types of instruments, and so on.)

Observatory X can detect dimmer stars and Observatory Y reveals more detail in images.

Which of the following is not a major reason why astronomers would like an observatory on the far side of the Moon?

Telescopes on the Moon could see objects in all parts of the sky equally well, whereas telescopes on Earth can see only portions of the sky that depend on their latitude.

Which of the following studies is best suited to astronomical observations that fall into the category called timing?

Studying how a star's brightness varies over a period of 3 years.

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