Astronomy Midterm
Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be __________.
greater than your normal weight at rest
_____________ a great circle on the celestial sphere 90 degrees from the zenith
horizon
_____________ the circle around us where the sky meets the ground
horizon
horizon
imaginary circle around you where the sky meets the ground
When we say that a planet has a highly eccentric orbit, we mean that:
in some parts of its orbit it is much closer to the Sun than in other parts.
Refracting telescopes use __________________
lenses
Refractor telescopes use __________ while reflecting telescopes use
lenses, mirrors
For a star (or other astronomical objects), a Doppler shift is a shift in the wavelength of spectral lines in an object's spectrum. The amount of this shift is a measure of the object's ___________________
speed toward or away from Earth
A galaxy is best described as a very large collection of _____.
stars
The sun spends the most amount of time above the horizon on the day of _______ solstice and the least amount of time above the horizon on the day of ______ solstice for an observer at the northern hemisphere.
summer, winter
When you are standing on a scale in an elevator, what exactly does the scale measure?
the force you exert on the scale
The word "apparent" in apparent retrograde motion is meant to imply that
the motion appears backward as we see it from Earth, but it is not really backward in space
The Andromeda Galaxy is located about 2.5 million light-years away. How long does its light take to reach us?
2.5 million years
The earth is tilted by _______ from the line perpendicular to the ecliptic
23.5
The sun's maximum altitude which is _____ happens on the day of _______
23.5, Summer solstice
What do we mean by Earth's "tilt"? We say that Earth's axis has a tilt of 23.5°, which means that __________.
Earth's axis is tilted at an angle of 23.5° compared to a line perpendicular (straight up and down) to its orbit
Why is a sunflower yellow?
It reflects yellow light.
______________ has a well-defined shape and border in the sky
constellation
Which person is weightless?
A child in the air as she plays on a trampoline
Which object emits more light?
A star that is the same size as the Sun but five times hotter
Longitudes are imaginary lines run from the________ Pole to the _________ Pole. Each is identified by the number of degrees it lies east or west of the so-called prime meridian which is located at the city of ______ in ___________
North, South, Greenwich, England
The distance between two adjacent peaks or the distance between two adjacent troughs is called
wavelength
The distance between two adjacent peaks or troughs in a wave is the definition of
wavelength
zenith
point directly overhead
Celestial objects are said to be ____________ shifted if they move away from us
red
A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:
redshifted
Circumpolar stars are stars that __________.
remain above the horizon at all times
Light is considered as an
electromagnetic wave
The Sun rises precisely due east and sets precisely due west only on the days of
equinoxes
The number of cycles in a wave is the definition of
frequency
_______________ is the number of waves that cross a given point per unit time.
frequency
Spring tide occurs when the moon is in the phase of
full moon
The moon has to be in the phase of _____ moon for total lunar eclipse while in the phase of _____ moon for the total solar eclipse
full, new
The moon must be in the phase of _______ for the lunar eclipse and the phase of _______ for the solar eclipse.
full, new
A supercluster is best described as a very large collection of _____.
galaxies
The Local Group is a collection of __________.
galaxies including the Milky Way and others nearby.
A car is accelerating when it is
going around a circular track at a steady 100 miles per hour
Light gets _______________ as it gets farther from its source
weaker
The Sun began to shine as a full-fledged star when nuclear fusion began inside of it, which was __________.
when our solar system was born about 4 ½ billion years ago
Latitudes are imaginary circles which are measured with respect to the ________ , which range from 0 degrees at the _______ to 90 degrees at the ________.
Equator, equator, poles
celestial equator
an imaginary circle between the north and south poles
Right ascension can be expressed either expressed in units of ______ (degrees) or in units of _____
angle, time
Objects which are located on the celestial equator have a declination of ______ degrees while an object which is located on the north celestial pole is going to have a declination of ______
0, 90
Tonight, you observe a star located 10 light-years away. When did the light you see tonight leave the star?
10 years ago
During a total eclipse, the moon or the earth is located in the umbra which is the dark part of the shadow
umbra
During an eclipse, there are two parts of the shadow. A dark shadow which is called ________ and bright one which is called _______
umbra, penumbra
_________ a point in the sky where the ecliptic (the Sun's path) crosses the celestial equator on March 21.
vernal equinox
The sun's minimum altitude which is _________ happens on the day of ________
-23.5, Winter solstice
Right ascension is measured from _______ degrees to ______ degrees where it's reference starting point is _________ equinox
0, 360, vernal
Description: Understanding Newton's Version of Kepler's Third Law. Find the orbital period for the planet in each case. (Hint: The calculations for this problem are so simple that you will not need a calculator.) A planet with twice Earth's mass orbiting at a distance of 1 AU from a star with the same mass as the Sun.
1 year
What is the best estimate for the age of the universe?
14 billion years
Two hours of right ascensions correspond to ______ degrees
30
Suppose a galaxy is located 10 billion light-years away. Given that the universe is now about 14 billion years old, how old was the universe at the time when the galaxy emitted the light we see today?
4 billion years
Description: Understanding Newton's Version of Kepler's Third Law. Find the orbital period for the planet in each case. (Hint: The calculations for this problem are so simple that you will not need a calculator.) A planet with the same mass as Earth orbiting at a distance of 1 from a star with four times the Sun's mass.
6 months
At the North Pole, the Sun rises when it reaches the vernal equinox and sets when it reaches the autumnal equinox. Each year there are _______ months of sunshine at each pole, followed by ________ months of darkness.
6, 6
full moon
Bright side of the moon faces Earth
Consider the statement "There's no gravity in space." This statement is:
Completely false.
Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:
Earth travels faster in its orbit around the Sun in January than in July.
new moon
Dark side of the moon faces Earth
According to our modern, Sun-centered model, planets rise in the east and set in the west each day because __________.
Earth rotates from west to east each day
______________ the path of the sun across the celestial sphere
Ecliptic
Latitude are lines of parallel circles which are measured with reference to
Equator
Longitudes are lines of meridians which are measured with reference to
Equator
All stars rise and set
False
True or False: Right ascension and declination are coordinate systems which are used to locate positions of objects on the surface of Earth
False
True or False: The moon must be in the phase of the new moon or full moon during low tides and the phase of the first and third quarter during high tides.
False
True or False: We have different seasons because the Earth is closer to the sun in summer and further away in winter.
False
True or False: We put telescopes into space to get closer to stars
False
True or False? As you accelerate upward, you have more mass than when you are stationary.
False
Newton's second law of motion states that force equals mass times acceleration or F=ma. Suppose you have already calculated the gravitational force, which we will call Fg, attracting Earth and the Moon. Then the amount of acceleration of Earth due to this force is __________.
Fg divided by the mass of the Earth
Newton's second law of motion states that force equals mass times acceleration or F=ma. Suppose you have already calculated the gravitational force, which we will call Fg, attracting Earth and the Moon. Then the amount of acceleration of Earth due to this force is __________.
Fg divided by the mass of the Earth
all planets orbit around the Earth
Geocentric model
all planets orbit around the Sun
Heliocentric model
Earth orbits around the Sun Sun and planets orbit around the Earth Geocentric model is proposed by Heliocentric model is proposed by
Heliocentric model Geocentric model Ptolemy Copernicus
When the sun, earth and moon lines up, we have
Spring Tide
Suppose you go outside and look at three stars. Star A is blue, Star B is white, and Star C is red. Which star is the hottest and which star is the coldest?
Star A is the hottest and Star C is the coldest.
Take a sheet of paper and drop it from shoulder height. Then pick it up, crumple it into a ball, and drop it again from the same height. What happens?
The crumpled paper falls to the ground faster.
Essentially all chemical elements heavier than hydrogen and helium, including carbon and oxygen, were made __________.
by nuclear fusion in massive stars
Suppose two cars both drive for one hour. Which statement is true?
The one that goes faster travels farther
In the Greek geocentric model, the retrograde motion of a planet occurs when:
The planet actually goes backward in its orbit around Earth.
You've now seen that Earth's varying distance cannot be the cause of our seasons. So what is the cause of the seasons?
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
True or False: During the day, we see most objects because of the reflected sunlight that enters our eyes.
True
True or False: The Earth has a bigger shadow than the moon and so the total lunar eclipse lasts longer than total solar eclipse
True
True or False: The solar system rotates around the center of the galaxy.
True
True or False: Tidal forces from the moon affect both the liquid part and the solid part of the earth
True
True or False: We put telescopes into space to come over the effect of the Earth's atmosphere
True
True or False: We put telescopes into space to come over the light pollution problem
True
True or False: When we look at the moon, we see the same face
True
The Earth rotates from
West to East
The point which is directly overhead in your local sky is called
Zenith
If you are in an elevator that is accelerating upward, you will feel __________ while the elevator __________.
a force pressing you to the floor; moves upward with increasing speed
star constellation
a group of stars within the same area in the sky and have a certain ship
Kepler's third law states that for any planet orbiting the Sun, the orbital period squared ( P2) is equal to the average orbital distance cubed (a3 ), or p2 = a3 . This implies that __________.
a planet with a large average distance from the Sun has a longer orbital period than a planet with a smaller average distance from the Sun
circumpolar star
a star which does not set
The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:
above Earth's atmosphere.
According to Newton's second law, the greater the force exerted on an object, the greater the object's _____.
acceleration
The universe is best defined as __________.
all the galaxies and everything within and between them
ecliptic
apparent path of the sun across the celestial sphere
According to Kepler's second law, as a planet or other object moves around its orbit, it sweeps out equal __________ in equal __________.
areas / times
When we look at the most distant observable objects in the universe, we see the
as they were about 14 billion years ago
What does retrograde mean?
backward
We say that the force of gravity follows an inverse square law with distance. This means that the force attracting two objects _________ as two objects come closer together
becomes stronger
Celestial objects are said to be ____________ shifted if they move toward us
blue
For Doppler effect, _________ shift means that the celestial object is moving toward you and ____________ means that the celestial object is moving away from you.
blue, red
Right ascension and declination are considered equatorial coordinate systems which are measured with respect to the
celestial equator
Tycho Brahe's contribution to astronomy included:
collecting data that enabled Kepler to discover the laws of planetary motion.
Ptolemy
developed geocentric model
Copernicus
developed heliocentric model
During a total lunar eclipse, the earth is in between the moon and the sun.
earth, moon
Compared to their values on Earth, on another planet your
mass would be the same but your weight would be different
Reflecting telescopes use _________________
mirrors
During a total solar eclipse, the moon is in between the earth and the sun.
moon, earth
According to Kepler's second law, planets and other objects orbiting the Sun move fastest when they are __________.
nearest to the Sun
According to the Greek Earth-centered model of the universe, apparent retrograde motion
occurred because planets moved in small circles that in turn moved in larger circles around Earth
The time a planet takes to complete one orbit is called its __________.
orbital period
We can see each other because we __________
reflect visible light
If there is going to be a total lunar eclipse tonight, then you know that:
the Moon's phase is full.
The fact that we always see the same face of the Moon tells us that
the Moon's rotation period is the same as the Earth's rotation period.
Our solar system is __________.
the Sun and the planets and other objects that orbit it.
retrograde motion
the apparent backward movement of a planet
An astronomical unit is equal to __________.
the average distance between Earth and the Sun
The time at which the Big Bang occurred can also be considered __________.
the birth of our universe
One light-year is equal to __________.
the distance light can travel in one year
first quarter
the moon is illuminated by 50%
last quarter
the moon is illuminated by 50%
In space or air, the speed of light is __________.
the same for light of all wavelengths
Compared to its angular momentum when it is farthest from the Sun, Earth's angular momentum when it is nearest to the Sun is
the same.
Order from smallest to the largest
the solar system; the Milky Way; the Local Group
The key discovery that led to the idea of the Big Bang was that __________.
the universe is expanding
Order from the largest to the smallest
the universe, the local supercluster,the local group, the Milky Way Galaxy, our solar system, the Sun, Jupiter, Earth
A week after full moon, the Moon's phase is:
third quarter
When we say that a quantity is conserved, we mean that its value does not change. Which of the following are examples of quantities that are conserved for a system of objects?
total momentum total energy total angular momentum
