Astronomy Test 1 Study
Which spectra has colorful lines?
Emission spectra
Infrared telescopes, which detect heat rays from the universe, must be kept as warm as possible (true or false)
False
One way to determine the age of a world that does not have a solid surface is to count the craters (true or false)
False
The Earth is closest to the Sun in which month of the year?
January
The scientist who formulated the three laws of planetary motion by analyzing the data on the precise location of planets in the sky was:
Johannes Kepler
What planets have no moons?
Mercury and Venus
If you were to take a large sample of the four giant planets, the most common element you would find in them is:
hydrogen
What is the order of wavelengths? (longest to shortest)
Radio Waves, Microwaves, Infrared, Visible, Ultraviolet, X-rays, Gamma Rays Real Men Imitate Vultures Using Xylophones Guiltily
All the planets (without exception) revolve around the Sun in the same direction (true or false)
True
Astronomers call the point directly above your head in the sky your zenith (true or false)
True
Compared to the mass of the Sun, the mass of the Earth is pretty insignificant (true or false)
True
In one year, the Sun completes a circle around our sky on the ecliptic (true or false)
True
Planets move faster when they are closer to the Sun (true or false)
True
The 17th century astronomer who kept a roughly 20-year continuous record of the positions of the Sun, Moon, and planets was:
Tycho Brahe
Rank the four terrestrial planets in our solar system by the thickness of their atmospheres, from thickest to thinnest.
Venus, Earth, Mars, Mercury
Imagine that Earth's orbit was changed to be a perfect circle around the Sun so that the distance to the Sun never changed over the course of one year. How would this affect our experience of seasons?
We would experience seasons in essentially the same way we do now.
Why is there a 4-minute difference between the solar day and the sidereal day?
because the Earth is going around the Sun in the course of a year
Why do different types of atoms (elements) give off or absorb different spectral lines?
because the spacing of the energy levels is different in different atoms
When an object moves toward you it is ________ shift and the wavelengths get ___________.
blue, shorter
On the celestial sphere, halfway between the celestial poles lies the
celestial equator
Using the inverse-square law for light, if we know a star's luminosity and can easily measure its apparent brightness, we can determine the star's...
distance
The fact that each type of atom has a unique pattern of electron orbits helps explain why
each type of atom shows different absorption or emission spectra
Which of the following was NOT done by Galileo Galilei?
explaining retrograde motion with the heliocentric hypothesis
Newton showed that to change the direction in which an object is moving, one needs to apply:
force
When do you see a continuous spectrum?
hot, dense energy through a prism
Which of the following is NOT an advantage that the Hubble Space Telescope has over large telescopes on Earth?
the Hubble has a larger aperture than any visible-light telescope on Earth
How many times wider is the Sun to the Earth?
the Sun is 109 times wider than the Earth
A light year is...
the distance that light travels in a year
From both crater counts and radioactive dating of moon rocks, scientists have found that the Moon is about 10,000 years old (true or false)
False
The scientist who first devised experimental tests to demonstrate the validity of the heliocentric model of the solar system was
Galileo
The large, roughly circular, dark, and somewhat younger regions on the Moon are called:
Maria
Order of the Planets
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What phase of the Moon must it be to have a solar eclipse?
New Moon
Stars that have a declination of zero degrees lie on the celestial equator (true or false)
True
The best places to put large telescopes (that observe visible light) are in locations that are at high altitude, very dry, and away from any sources of light (true or false)
True
The farther away the planet is from the Sun, the slower it orbits (true/false)
True
The larger the ellipse, the slower overall the planet moves (true/false)
True
The more craters we can count on the surface of a moon, the older that surface must be (true or false)
True
The most common element (type of atom) in the outer layers of Jupiter is also the most common in the Sun (true or false)
True
The reason we have a regular cycle of day and night on Earth is that our planet rotates on its axis (true or false)
True
The resolution of a telescope is the size of the smallest feature that can be distinguished on images obtained by using it (true or false)
True
To improve the resolution of telescopes on Earth, astronomers use adaptive optics (true or false)
True
Today, when astronomers use the term constellation, they mean one of 88 boxes into which they divide the sky (true or false)
True
What specific event really made it possible for the three laws of planetary motion to be discovered?
Tycho Brahe died and his assistant was able to get full access to his data
The smaller objects in the solar system composed mainly of ices (frozen gases) that usually orbit far from the Sun are called:
comets
The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called
constellations
When do you see an emission spectrum?
cool, low density cloud of gas through a prism
What is one way that astronomers have actually gotten an idea of the age of the surfaces of terrestrial planets other than the Earth?
counting craters
A friend of yours who takes her astronomy class very seriously challenges you to a contest to find the thinnest crescent moon you can find just after new moon? What time of day is best for looking for this very thin crescent?
just as the Sun is setting, or just after
How do astronomers learn what elements are present in a given star?
look at the absorption lines in its spectrum
Using the inverse-square law for light, if we know a star's distance and can easily measure its apparent brightness, we can determine the star's...
luminosity
An astronomer discovers a new star and wants to measure its temperature. She would typically do this by:
making a blackbody curve and finding the wavelength of the peak (maximum)
How to calculate weight on another planet.
mass (compared to Earth)/radius^2 (compared to Earth) = weight on that planet (in terms of the weight on Earth)
When an object moves away it is ________ shift and the wavelengths get ___________.
red, longer
The higher the energy the ___________ the wavelength
shorter
The higher the frequency the ___________ the wavelength
shorter
The celestial sphere turns once around each day because
the planet on which we live is rotating
In Ptolemy's system, the planets orbit the Earth and not the Sun. How did the system explain the retrograde motion of planets like Jupiter?
the planets moved on a small circle whose center, in turn, circled a point near the Earth
When a planet, in its orbit, is closer to the Sun, it:
moves faster than average
When a planet temporarily moves westward in the sky over the course of several weeks or months (instead of eastward, as it typically does), we call it:
retrograde motion
The Stefan-Boltzmann Law relates the energy flux coming from a blackbody (such as a star) to its:
temperature
Formula for Weight of a Planet
(G*M)/r^2
Please put the planets in order of what you would weigh, from least to most. Planet 1: Same mass and radius Size as Earth Planet 2: 4 times Earth's mass and radius Planet 3: 1/2 Earth's Mass, same radius Planet 4: Same mass as Earth's, 1/2 Earth's radius Planet 5: 1/2 Earth's mass, 1/2 Earth's radius
2 ,3, 1, 5, 4
A star is 230 light-years away. The light we see tonight from that star left it
230 years ago
Which spectra is a rainbow with dark lines?
Absorption spectrum / Dark line spectrum
What's a characteristic of an asteroid, comet, or both (sort it) -rocky/metallic composition -icy/rocky composition -remnants of the formation of the solar system -mostly found orbiting in the outer solar system -mostly found orbiting between Mars and Jupiter -generally not large enough to have differentiated interiors
Asteroid: rocky/metallic, orbiting between Mars and Jupiter Comet: icy/rocky, orbiting in the outer solar system Both: remnants of the creation of solar system, generally not large enough for differentiation
Which spectra looks like a rainbow?
Continuous Spectra
All the planets in the solar system are similar in terms of what materials they are mostly made of (true or false)
False
All four of the terrestrial planets have large moons (true or false)
False
The band of star patterns that the celestial equator crosses is called the zodiac (true or false)
False
The eight planets may be different in size, but they all have roughly the same density (true or false)
False
The most common detector used with large visible-light telescopes on Earth is the human eye (true or false)
False
The path that the Sun appears to make in the sky over the course of a year is called the celestial equator (true or false)
False
To improve the resolution of their telescopes, astronomers want to be as close to sea-level on Earth as possible (true or false)
False
While humans and robot spacecraft have landed on the Moon, no robot spacecraft have yet landed on another planet (true or false)
False
The first radio telescope was built in the 1930's by
Karl Jansky
The great astronomer of ancient times who summarized and improved a system of circles upon circles to explain the complicated motions of the planets (and published the system in a book now called The Almagest) is:
Ptolemy
An astronomer observes two ordinary stars that are the same size. The first one turns out to be twice as hot as the second. This means that the first one radiates:
about 16 times the energy of the second
To go from a lower level in an atom to a higher level, an electron must
absorb a photon of energy
To overcome the problems that blur images and don't provide the best resolution from Earth, astronomers have started using flexible mirrors that change shape many times each second. This technique is called:
adaptive optics
We now know that the orbit of a stable planet around a star like the Sun is always in the shape of:
an ellipse
When it comes to our place in the solar system today, which model do we accept?
heliocentric
When do you see an absorption spectrum?
hot, dense energy passes through cool, low density cloud of gas
The shorter the wavelength the __________ the temperature.
hotter
The idea that objects (in the absence of an outside force) tend to continue doing what they are already doing is called the law of
inertia
The Julian calendar made the significant advance of:
introducing the leap year, so that every fourth year had an extra day
In studying the surfaces of solid bodies in the solar system, astronomers have learned that the number of craters (per unit area):
is roughly proportional to the age of the surface we are examining
According to the geocentric view, everything in the heavens had to go around the Earth, which was the center of the universe. What objects did Galileo discover with his telescope that clearly didn't go around the Earth?
moons around the planet Jupiter
How many times wider is the Earth to the moon?
the Earth is 4 times wider than the moon
The Astronomical Unit (AU) as defined by astronomers is
the average distance between the Earth and the Sun
In an ellipse, the ratio of the distance between the foci and the length of the major axis is called:
the eccintricity
The Sun's apparent path around the celestial sphere is called
the ecliptic
Suppose two stars have the same apparent brightness but one is more distant than the other. What can you say about these two stars relative to each other?
the more distant star is more luminous
What zodiac sign do you see in the sky? -the one on the other side of the Sun (Earth -> Sun -> Star) -the one behind the Earth (Star -> Earth -> Sun)
the one behind the Earth
What zodiac is the current one? -the one on the other side of the Sun (Earth -> Sun -> Star) -the one behind the Earth (Star -> Earth -> Sun)
the one on the other side of the Sun
The strip of the sky through which the Sun, the Moon, and the bright planets appear to move in the course of a year is called
the zodiac
Which of the following characteristics do all four terrestrial planets have in common?
they all have solid surfaces with signs of geological activity on them
A single star in the process of forming starts by spinning slowly (while it is quite large and relatively cool.) As the star collapses under the pull of its own gravity, its size decreases. As a result, its rate of spinning:
will increase
Which of the following types of telescopes can be used ONLY above the Earth's atmosphere?
x-ray telescope
The point in the sky directly above your head at any given time is called the
zenith
