AST 104 - FINAL EXAM (HW 1-11)

Which of the following types of electromagnetic radiation can reach the ground through Earth's atmosphere? (Select all that apply.) A) X-Rays B) Radio Waves C) Gamma Rays D) Visible light

B and D Radio Waves and Visible light

A star would emit more light if we could... (select all that apply) A) make it cooler B) make it larger C) bring it closer D) raise its temperature.

B and D Make it larger and raise its temperature

The range of apparent magnitudes of stars (besides the Sun) that you can see with the unaided eye from Earth is about... A) 0 to +100 B) -1 to +6 C) -8 and +16 D) 32 to 212

B) -1 to +6

The Solar System has a diameter of roughly 10^10 km, while the Milky Way Galaxy is about 10^18 km across. How much bigger is the Milky Way Galaxy compared to the Solar System? A) 8 times bigger B) 10^8 times bigger C) 10^18 times bigger D) 10^28 times bigger

B) 10^8 times bigger

The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called A) Zodiacs B) Constellations C) Asterisms D) Epicycles

B) Constellations

Why is an absorption spectrum especially useful for astronomers? A) It has bright lines in it which allow astronomers to determine what elements are in the star. B) It has dark lines in it that allow astronomers to determine what elements are in the star. C) It has bright lines in it that allow astronomers to determine how bright the star is. D) It helped astronomers to understand the rainbows we see on Earth after storms.

B) It has dark lines in it that allow astronomers to determine what elements are in the star.

The red dwarf star Trappist-1 has an absolute magnitude of M = +18.4. How does its luminosity compare to that of the Sun? A) It is much more luminous B) It is much less luminous C) It as about as luminous

B) It is much more luminous

Earth's axis is tilted by about 23.5 degrees relative to its orbit around the Sun. If the axis were tilted by a larger obliquity angle, the seasons would be... A) Unchanged B) More extreme C) Less extreme D) Non-existant

B) More extreme

Star A has an apparent magnitude of 1.5 while Star B has an apparent magnitude of 3.5. How do they compare in brightness? A) Star A is 2.5 times brighter. B) Star A is 6.25 times brighter. C) They are the same brightness. D) Star B is 6.25 times brighter. E) Star B is 2.5 times brighter.

B) Star A is 6.25 times brighter. Lecture 2

The speed needed to move away from Earth forever is called ______.

Escape Speed

Newton's law implies that gravitational force between two massive objects can become zero. True False

False

True or False? When we see the light coming from an object, we are seeing the way it looks right now?

False

Jupiter

Four moons revolving about this celestial body

Comets

Highly elliptical orbits

The Sun's surface temperature is about 5800 K. Suppose another star were the same size but cooler (5000 K) than the sun. What would that star's luminosity be?(Express your answer as a multiple of the Sun's luminosity LSun to two decimal places but input only the number so Blackboard counts it. For example, if the star were 70% as luminous as the sun, you would input 0.70 only.)

0.55 Lecture 6

A planet like Earth is found orbiting its star at a distance of 0.8 AU in 1.2 Earth-years. Use Newton's version of Kepler's third law to find the mass of the star. (Remember that compared to the mass of a star, the mass of an earthlike planet can be considered negligible.) Express your answer in "solar masses" rounded to the nearest 0.01, entering the numerical value only. E.g. if the star's mass is 15% of the Sun's mass, enter 0.15. (If you include text, your answer won't be marked correct!) Hint: Follow Example 3.4 in Chapter 3.3!

0.35

Recall that Newton's Universal Law of Gravitation allows us to calculate the force exerted on our bodies by the Earth while we stand on the surface, e.g. our weight. Suppose you stood instead on the surface of Mars. How much would you weigh on Mars compared to your weight on Earth? Express your answer as a decimal fraction (e.g. enter something like 0.25 if you would weigh 25% of your Earth-weight). Mars has a mass that is about one tenth that of the Earth. Mars has a surface radius that is about half that of the Earth.

0.4

Order the following stars according to spectral class from hottest to coolest. Capella (G3) Spica (B1) The Sun (G2) Trappist-1 (M8) Sirius (A0) Polaris (F7)

1. Spica (B1) 2. Sirius (A0) 3. Polaris (F7) 4. The Sun (G2) 5. Capella (G3) 6. Trappist-1 (M8)

Rank the following by size (from smallest to largest): - The Pleiades Star Cluster - The Earth-Moon System - The Solar System - The Milky Way Galaxy

1. The Earth-Moon System 2. The Solar System 3. The Pleiades Star Cluster 4. The Milky Way Galaxy

TRAPPIST-1 is a red dwarf star hosting three Earth-sized planets. Its spectrum is peaked at about 1200 nm. What is this star's temperature?(Express your answer in Kelvin but only input the number so that Blackboard will count it!)

2,500 Lecture 5

Suppose a star with twice the mass of our Sun had an Earthlike planet that took 3 years to orbit the star. At what distance (semimajor axis) would this planet orbit its star? Remember that the mass of an Earthlike planet is negligibly small compared to the mass of a star, so you can use the expression from section 3.3 for Newton's formulation of Kepler's third law to find the answer (in astronomical units, AU). Please round to the nearest tenth and input the numerical value only. Hint: Follow Example 3.4 in Chapter 3.3!

2.6

The star Vega in the constellation Lyra has a temperature of about 9600 K. What is the peak wavelength of its spectrum? (Express your answer in nanometers but input only the number so Blackboard can count it!)

312.5

The star Bellatrix has an apparent magnitude m = 1.64 and absolute magnitude M = -2.78. Nearby on the sky, Rigel has an apparent magnitude m = 0.13 and absolute magnitude M = -7.84. Which of the following statements is/are true about these two stars? (Select all answers that apply.) A) Rigel is brighter in Earth's sky than Bellatrix. B) Bellatrix is more luminous than Rigel. C) Rigel is more luminous than Bellatrix.

A & C Rigel is brighter in Earth's sky than Bellatrix and Rigel is more luminous than Bellatrix.

In searching for a planet very similar to Earth, which star is most similar to the Sun and would therefor make the best candidate to study? A) 61 Ursae Majoris (class G8) B) Spica (class B1) C) Vega (class A0) D) Gliese 581 (class M3

A) 61 Ursae Majoris (class G8)

What happens when an electron transitions from a higher energy level to a lower energy level in an atom? A) A photon is given off. B) The color of the wave involved shifts to the red. C) A photon is absorbed D) Another electron from the lower level takes its place.

A) A photon is given off.

Of the following planets - Venus, Earth, Mars, Jupiter which has the largest... eccentricity A) Mars B) Earth C) Venus D) Jupiter

A) Mars

Why do the planets orbit the Sun? A) The Sun's gravitational attraction keeps them in elliptical orbits. B) The Earth's motion around the Sun causes them to appear along the ecliptic. C) The Celestial Sphere carries them around the Sun once per year. D) They don't! They follow paths around the Earth augmented by epicycles.

A) The Sun's gravitational attraction keeps them in elliptical orbits.

An incandescent light bulb (the old-fashioned kind with a hot wire inside) glows yellow-white. The burner on an electric stove glows red hot. Which has the higher temperature? A) The light bulb's filament is hotter. B) There is not enough information to answer the question. C) The burner on the electric stove is hotter.

A) The light bulb's filament is hotter.

The celestial sphere turns once around each day because... A) The planet on which we live is rotating B) The Earth is going around the Sun C) The phases of the Moon D) Precession

A) The planet on which we live is rotating

Stars with larger parallax angle are __________ stars with smaller parallax angle A) closer than B) the same distance as C) farther than

A) closer than

The inward crushing force of the Sun's mass under its own gravity is balanced by the outward explosive pressure from heat released by fusion in the core in an example of A) equilibrium. B) nuclear fission. C) convection. D) a solar prominence.

A) equilibrium

Absolute magnitude is a measure of... A) luminosity B) distance C) how bright a star looks to us

A) luminosity

Gravity is an extremely important force in astronomy because... A) some objects in the universe have incredibly large masses. B) gravity is always attractive. C) gravity only acts on nearby objects like those near planets and stars. D) gravity causes a force that is independent of mass. E) gravity extends forever in distance. F) gravity both attracts and repels.

A, B and E some objects in the universe have incredibly large masses, gravity is always attractive and gravity extends forever in distance.

From Syracuse, which part or parts of the celestial sphere can be seen? (select all that apply) A) the north celestial pole B) the celestial equator C) the north celestial pole D) the celestial equator

A, B, C & D the north celestial pole, the celestial equator, the north celestial pole and the celestial equator

The positions of the Sun, Moon, and planets among the stars of the zodiac (select all that apply) A) were once thought to determine what we can expect from life. B) can remind you what time of year it is. C) were once thought to determine what we can expect from life. D) can physically influence day-to-day events on Earth. E) can remind you what time of year it is.

A, B, C and E were once thought to determine what we can expect from life, can remind you what time of year it is, were once thought to determine what we can expect from life, and can remind you what time of year it is.

A graduate student in geology who grew up in Florida (near the southernmost tip of the United States) gets to accompany her research professor to the North Pole. What view or views of the sky will be different at the North Pole from the way she remembers the sky in Florida? (Select all that apply.) A) The North Celestial Pole is overhead. B) The Celestial equator is on the horizon. C) The way (and whether) the stars rise or set. D) The North Celestial Pole is overhead. E) The Celestial equator is on the horizon. F) The way (and whether) the stars rise or set.

A, B, C, D, E & F The North Celestial Pole is overhead, The Celestial equator is on the horizon, The way (and whether) the stars rise or set, The North Celestial Pole is overhead, The Celestial equator is on the horizon and The way (and whether) the stars rise or set.

Which of the following statements about electromagnetic radiation is/are TRUE? (Select all that apply.) A) It is given off by all objects that are not at a temperature of absolute zero. B) It always travels through empty space at the speed of light. C) It cannot travel through the empty vacuum of space. D) Different types of electromagnetic radiation differ in their wavelength. E) It is always detectable by the human eye. F) It is given off by all objects that are not at a temperature of absolute zero. G) It always travels through empty space at the speed of light.

A, B, D, F, and G It is given off by all objects that are not at a temperature of absolute zero, It always travels through empty space at the speed of light, Different types of electromagnetic radiation differ in their wavelength, It is given off by all objects that are not at a temperature of absolute zero, It always travels through empty space at the speed of light

Which of the following contribute in a meaningful way to seasons at a location on Earth? (Select all that apply.) A) the altitude of the sun's rays B) the proximity of the Earth to the Sun C) the amount of time that the sun is above the horizon D) the altitude of the sun's rays E) the phase of the moon

A, C and D the altitude of the sun's rays, the amount of time that the sun is above the horizon and the altitude of the sun's rays

Which of the following are true statements about the gravitational force between two masses labeled m and M? A) the mass m is being pulled toward mass M. B) the force decreases if the distance R between the two masses is decreased. C) the force increases if the mass of M were to be increased. D) the force decreases if the mass of m were to be decreased. E) the mass M is being pushed away from mass m.

A, C and D the mass m is being pulled toward mass M, the force increases if the mass of M were to be increased, the force decreases if the mass of m were to be decreased.

Of the following planets - Venus, Earth, Mars, Jupiter which has the largest... semi major axis A) Mars B) Earth C) Venus D) Jupiter

D) Jupiter

Microwave

Active galaxies

The Milky Way

Actually made up of a multitude of individual stars

Where does the energy released by fusion of hydrogen into helium come from? A) Convection of hydrogen under the surface of a star mixes it with oxygen to form helium. B) The difference in mass of the hydrogen and helium is converted to energy in the form of heat. C) The light emitted by the hydrogen is absorbed by the helium. D) Intense magnetic fields lift hydrogen and burns with oxygen it to release heat.

B) The difference in mass of the hydrogen and helium is converted to energy in the form of heat.

Why are astronomers much more interested in the luminosity of a star than its apparent brightness? A) The luminosity also tells us what elements the star is made of, while apparent brightness cannot. B) The luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth. C) There is no difference between luminosity and apparent brightness. They are merely different terms for the same property of a star.

B) The luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth.

An astronomer discovers a new star and wants to measure its temperature. She would typically do this by... A) measuring how much light the star reflects. B) matching its spectrum to a blackbody curve and finding the wavelength of the peak. C) measuring the intensity of radio waves the star gives off. D) measuring the Doppler shift of its spectral lines. E) sending a graduate student with a very long (and durable) thermometer to the star's vicinity.

B) matching its spectrum to a blackbody curve and finding the wavelength of the peak.

Where can the other planets in our solar system generally be found on the sky? A) along the band of the Milky Way B) near the ecliptic C) near the celestial equator D) near the Earth's perihelion E) near the local zenith

B) near the ecliptic

What process is primarily responsible for powering the light emitted by most stars? A) nuclear fission of uranium into lighter elements B) nuclear fusion of hydrogen into helium C) hot gas lifted over the star's surface by intense magnetic fields D) combustion of hydrogen with oxygen

B) nuclear fusion of hydrogen into helium

What is the approximate angular size of a fist held at arm's length? A) 10 arcmin B) 10 arcsec C) 10 degrees D) 10 radians

C) 10 degrees

What was the surprising finding of Cecilia Payne's 1925 doctoral thesis on the elemental composition of stars? A) All stars contain elements in similar amounts to those found on Earth. B) All stars contain only helium (hence its name). C) All stars are composed of mostly hydrogen and some helium, with only traces of other elements. D) Stars are made up mostly of nitrogen, oxygen, and argon like the Earth's atmosphere.

C) All stars are composed of mostly hydrogen and some helium, with only traces of other elements.

We shine the light of an incandescent lamp through a cloud of cooler gas. What is the form of the spectrum we observe? A) All wavelengths are present in the spectrum. B) Just a few wavelengths are present in the spectrum. C) Almost all wavelengths are present in the spectrum, but a few special wavelengths are missing.

C) Almost all wavelengths are present in the spectrum, but a few special wavelengths are missing.

The familiar collection of stars known as "The Big Dipper" is... A) A Constellation B) A Solar System C) An Asterism D) A Star Cluster

C) An Asterism

Which star is currently closest to the North Celestial Pole? A) Arcturus B) Betelgeuse C) Polaris D) Rigel

C) Polaris

What was Annie Jump Cannon's insight into spectral classes? A) Spectral classes should be ordered by hydrogen absorption from strongest to weakest. B) Spectral classes with lots of heavy element absorption lines should be excluded. C) Spectral classes should be ordered by temperature from hottest to coolest. D) Spectral classes should be divided into 10 subclasses.

C) Spectral classes should be ordered by temperature from hottest to coolest.

Why do stars appear at different positions on the sky at the same time each night? (Select the best answer.) A) The Earth is rotating on its axis once per day. B) The distance between the Earth and the stars is chaning from day to day. C) The Earth's position around the sun is changing each day. D) The Earth's rotational axis is precessing over time. E) The Celestial Sphere is slowly rotating around the Earth once per year.

C) The Earth's position around the sun is changing each day.

One reason that human eyes evolved to detect visible light is... A) it is the band of the electromagnetic spectrum with the lowest possible energy and thus easiest to detect. B) it is the only band of the spectrum that can travel through a vacuum. C) it is a band of the spectrum where the Sun puts out a great deal of energy. D) it is the band of the spectrum where the warm Earth glows the most effectively at night.

C) it is a band of the spectrum where the Sun puts out a great deal of energy.

Radio

Cold gas

Infrared

Cool clouds of dust and gas

The Moon

Craters, mountain ranges, valleys, and flat, dark areas

About how large is the constellation Orion in angular size? A) 1 degree B) 2 degrees C) 8 degrees D) 20 degrees

D) 20 degrees

A star is 230 light-years away. The light we see tonight from that star left it... A) One year ago B) 2.3 years Ago C) 23 years ago D) 230 years ago

D) 230 years ago

From a city in the U.S., where in the sky would you look to see a star that is not turning with the motion of the sky in the course of a night? A) On your horizon B) At your zenith C) On the celestial equator D) At the north celestial pole

D) At the north celestial pole

Of the following planets - Venus, Earth, Mars, Jupiter which has the largest... orbital period around the sun A) Mars B) Earth C) Venus D) Jupiter

D) Jupiter

Two stars have the same diameter and are at the same distance from us (but in different parts of the sky.) Star A has a temperature of 4000 K, while star B has a temperature of 8000K. Which of the following statements is true? A) The two stars have the same total luminosity. B) Star B has twice the luminosity that Star A has. C) Star B has one half the luminosity that Star A has. D) Star B has 16 times the luminosity that Star A has.

D) Star B has 16 times the luminosity that Star A has.

Which constellation of stars is directly behind the Sun from Earth's perspective during the month of June? A) Sagittarius B) Pisces C) Cancer D) Taurus

D) Taurus

The south celestial pole and the north celestial pole lie in the sky directly along... A) The Earth's Equator B) The Oberver's Zenith C) The Ecliptic D) The Earth's Axis

D) The Earth's Axis

The point on the sky directly overhead is called A) A Celestial Pole B) The Local Meridian C) The Nadir D) The Zenith

D) The Zenith

Which of the following stars would be the brightest, as seen in our sky? A) apparent magnitude m = 10 B) apparent magnitude m = 1 C) apparent magnitude m = 6 D) apparent magnitude m = -1

D) apparent magnitude m = -1

When an astronomer rambles on and on about the luminosity of a star they are studying, they are talking about... A) the star's color. B) the total amount of mass in the star. C) the star's apparent size (the size seen from Earth). D) how much energy the star gives off each second.

D) how much energy the star gives off each second.

As astronomers use the term, the parallax of a star is A) always equal to 1 AU. B) always equal to 1 arcsec. C) the time it takes for a star to move one second of arc of proper motion. D) one half of the angle that a star shifts when see from opposite sides of the Earth's orbit.

D) one half of the angle that a star shifts when see from opposite sides of the Earth's orbit.

Syracuse is at a latitude of 43 degrees north. In our sky, we can see... A) only stars in the Northern Celestial Hemisphere. B) only stars with right ascension greater than 43 hours. C) only stars with magnitude larger than 43. D) some stars in both the Northern and Southern Celestial Hemsipheres.

D) some stars in both the Northern and Southern Celestial Hemsipheres.

The ecliptic is... A) the ratio of the distance between the foci to the major axis of an ellipse. B) the point in its orbit where a planet (or other orbiting object) is nearest to the Sun. C) a great circle on the celestial sphere 90° from the celestial poles; where the celestial sphere intersects the plane of Earth's equator. D) the apparent annual path of the Sun on the celestial sphere.

D) the apparent annual path of the Sun on the celestial sphere.

Using a good pair of binoculars, you observe a section of the sky where there are stars of many different apparent brightnesses. You find one star this appears especially dim. This star looks dim because it is A) very far away. B) very low luminosity. C) radiating most of its energy in the infrared region of the spectrum. D) partly obscured by a cloud. E) It could be more than one of the above. There is no way to tell which answer is right just by its apparent brightness.

E) It could be more than one of the above. There is no way to tell which answer is right just by its apparent brightness.

Venus

It goes through phases in an order that agreed with the Copernican theory and not Ptolemy's model

Gamma rays

Nuclear reactions

Rank the following stars from dimmest to brightest in the sky. Spica (m = 0.97) Sirius (m = -1.46) Deneb (m = 1.25) Saiph (m = 2.06)

Saiph (m = 2.06) Deneb (m = 1.25) Spica (m = 0.97) Sirius (m = -1.46)

X-rays

Solar corona

Visible

Typical stars

Ultraviolet

Very hot stars

Define The Universe

everything that we can observe

Planets

nearly circular

see blackboard (HW1, Q19) "Use planetarium software like Stellarium"

see blackboard (HW1, Q19)

see blackboard (HW1, Q20) "Use planetarium software like Stellarium"

see blackboard (HW1, Q20)

see blackboard (HW1, Q21) "Use planetarium software like Stellarium"

see blackboard (HW1, Q21)

see blackboard (HW1, Q22) "Use planetarium software like Stellarium"

see blackboard (HW1, Q22)

see blackboard (HW1, Q23) "Use planetarium software like Stellarium"

see blackboard (HW1, Q23)

see blackboard (HW1, Q24) "Use planetarium software like Stellarium"

see blackboard (HW1, Q24)

see blackboard (HW1, Q25) "Use planetarium software like Stellarium"

see blackboard (HW1, Q25)

see blackboard (HW2, Q11) "Match each hemisphere with the season it is experiencing in the above image."

see blackboard (HW2, Q11)

see blackboard (HW2, Q14) "Examine the following image of the Moon at different points along part of its orbit around the Earth. The sun is illuminating the Earth and the Moon from the left. Match each of the following pictures of the moon to the appropriate location(s) in the Moon's orbit where it would be seen in the phase depicted in the picture."

see blackboard (HW2, Q14)

see blackboard (HW2, Q21) "Use the following table of planetary orbit data to order the following planets by orbital period P from shortest (1) to longest (6)."

see blackboard (HW2, Q21)

see blackboard (HW2, Q25) "Match the following deep sky objects with the type of object each represents."

see blackboard (HW2, Q25)

see blackboard (HW3, Q1) "Rank the following types of light from LOWEST ENERGY (1) to HIGHEST ENERGY (7)."

see blackboard (HW3, Q1)

see blackboard (HW3, Q15) "The blackbody curves for three stars of the same size are shown below. Which of these stars emits the most red light?"

see blackboard (HW3, Q15)

see blackboard (HW3, Q16) "The blackbody curves for three stars of the same size are shown below. Which of these stars appears the reddest color to human eyes?"

see blackboard (HW3, Q16)

see blackboard (HW3, Q17) "The image above shows the total energy radiated at different wavelengths by three different stars. Each star has a different size and temperature. Which of the following statements is/are true? (Select all that apply.)"

see blackboard (HW3, Q17) (The more narrow the wavelength, the higher the temperature is) (So on this graph, A is hottest and C is coolest)

see blackboard (HW3, Q23) "Below is a snapshot of a discharge lamp containing a low-pressure element in gas form and its emission spectrum spread out by a diffraction grating." "Use the following chart of example emission spectra to identify the element above."

see blackboard (HW3, Q23)

Define The Local Group.

the collection of several dozen galaxies, of which the Milky Way is one

Define The Milky Way Galaxy

the system of 200 to 400 billion stars, of which the Sun is one

Define The Solar System

the system of the Sun, its planets and moons, and small pieces of debris that surround it

Interstellar Objects

unbound hyperbolic orbits