astronomy final 😵‍💫

The orbital velocity of stars in our galaxy follows the predictions of Newton's version of Kepler's Laws. T or F

false

The approximate upper limit of the corpse mass of a giant star that will result in a neutron star is more than (a) 10 times the mass of the Sun, (b) 2 times the mass of the Sun, (c) 3 times the mass of the Sun.

(c) 3 times the mass of the Sun.

What is the range of masses of stars?

0.1M sun to 60M sun

What is the approximate angular size of the moon in our sky?

0.5 degrees

State Kepler's laws of planetary motion. Define all terms if equations are used.

1. Each planet orbits the Sun is an eclipse with the sun at one focus. 2. As a planet orbits the Sun, it sweeps out equal areas in equal times. 3. More distant planets orbit the sun at slower speeds, obeying the precise math relationship p2=a3, where p is the period in Earth years and a is the average distance from the sun of the planets in astronomical units (AU)

Our fusion is a very energetic, violent process. How does the output of the sun remain steady, e.g. , describe the solar thermostat.

1. Equilibrium is established by balancing pressure from gravitational forces with the force of expanding gases from the nuclear process. 2. Energy balance of the energy radiated into space and the energy generated by the fusion process.

State Newtons, universal law of gravitation. define all terms used.

1. Every mass attracts every other mass. 2. Attraction is directly proportional to the product of their masses. 3. attraction is inversely proportional to the square of the distance between their centers. F= g(M1M2/d^2) Where F = force, G is the universal gradational constant, M1M2 are the masses of two objects, and D is the distance between their centers.

List the two most distinctive features of the orbits of the planets in our solar system.

1. all orbit the sun in nearly circular elliptical orbits 2. all orbit the sun in a counter clockwise direction (as seen looking down on the earth's north pole)

What are two common, defining characteristics of main sequence stars?

1. main sequence stars fuse hydrogen and helium in their cores 2. stars will spend most of their lifetime in the main sequence because this is the stage in their life where they are the most stable. gravitational equilibrium creates a balance of the inward crush of gravity and the outward pressure of fusion in the core

If there is going to be a total lunar eclipse tonight, then what two things must be true?

1. must be full moon 2. moon must be at one of the two nodes where its orbit interacts the plane of the earth's orbit

What is the range of masses (in terms of solar mass) of neutron stars?

1.4 M sun - 3.0 M sun

What is the approximate diameter of our galaxy's disc?

100,000 ly (50,000 pc)

What is the approximate range of luminosities of stars?

10^-5 solar units to 10^6 solar units

What is the range of stellar lifetimes?

10^7 years to 10^11 years

the radius of the observable universe is about ____ light years old.

14 billion

What is the approximate tilt of the Earth's axis relative to the ecliptic?

23.5 degrees

What is the approximate period of rotation of the sun about the center of the Milky Way?

230 million years

What is the range of temperatures of stars?

3,000 K to 30,000 K

Expressed in solar masses, what is the approximate lower limit of the mass of a corpse of a large star that will result in the formation of a black hole?

3.0 M sun (3 solar masses)

The angular size of your finger at arms length is about 1 degree. What is it in arcseconds?

60 x 60 = 3600 or 1 degree --> 3600 arcseconds

And asteroid orbits the sun at an average distance of a = 4 AU. How long does it take to orbit the sun? 4, 8, 16, or 64 years?

8

Approximately what percentage of the total mass of our solar system is contained in the Sun?

99.9%

When it is summer in Australia, the season in the United States is. A ) winter b) spring C ) summer.

A ) winter

what is a star

A large, glowing ball of gas that generates heat and light through nuclear fusion

The sun rises precisely due east. A) You must be at the earth's equator. B) It must be the day of either the March or the September equinox. C) It must be the day of the summer solstice.

B) It must be the day of either the March or the September equinox.

Why do sunspots appear darker than the surrounding areas of the sun?

Because their temperature is lower than the surrounding areas and the amount of power radiated depends on T^4

What is a Black Hole?

Black holes are corpses of extremely large stars; Mass left over after Supernova greater that 3x Sun's mass

Mercury has the highest surface temperature of the eight major planets. T or F

false

The parallax of Star A is twice that of star B. This means that a ) the stars are the same distance from you b) Star B is twice as far away as star A, C ) star B is half the distance of star A.

C ) star B is half the distance of star A.

The sun's surface temperature is about. A) 10,000 K. b) 2,000 K. C) 6,000 K.

C) 6,000 K.

The moon always keeps the same side toward the earth. This is because the moon a) Does not rotate on its axis. B) The moon rotation about its axis is in the opposite direction as its orbital motion. C) The moon rotates on its axis at the same period as the period of its orbit around the earth.

C) The moon rotates on its axis at the same period as the period of its orbit around the earth.

Why do the stars rise and set?

Earth rotates west to east, so stars appear to circle from east to west

What is the end product of an interstellar gas and dust cloud with mass less than 0.08 times the mass of the Sun?

Electron degeneracy prevents the gravitational collapsed to high enough density and temperature for hydrogen fusion to take place. It becomes a Brown Dwarf star.

State Newtons laws of motion. define all terms if equations are used.

First law: an object moves at a constant velocity unless a net force acts to change its speed or direction. Second law: force equals mass times acceleration. Or force = Rate of change in momentum. (p=mv) Third law: For every force, there is always an equal and opposite reaction force.

What are the two elements that make up 98% of the sun's mass?

Helium and hydrogen.

How is mass different from weight?

Mass = quantity of matter in an object. Weight = force acting on mass.

List the 8-major planets of our solar system in order of their distance from the Sun.

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

Define momentum.

P=mv P=momentum M=mass V=velocity

What is the Star-Gas-Star Cycle?

Stars through stellar wind and material (star stuff) as they nova and super nova. This gas and dust form huge clouds that cool and are compacted by gravity. Gravity continues to compact and heat the material to form new stars.

What is a White Dwarf star?

The corpse of a low to medium mass star that no longer supports fusion.

What is the proton-proton process?

The nuclear fusion process by which four hydrogen nuclei are fused to form one helium nucleus plus energy: 4 H^1 ==== 1 He^4 + gamma rays and neutrinos (energy)

Luminosity is defined as.

Total power (rate of energy emission) radiated by a body (star)

How do we determine the sun's temperature?

We measure the peak of its Spectra and use weins law.

In the winter, Earths axis point towards Polaris. In the spring, the access points toward a ) Polaris b) Vega C ) the Sun.

a ) Polaris

What is Sgr A*?

a supermassive black hole at the center of the milky way approximately 4 million solar mass black hole

Saturn orbital radius about the Sun is about a) 10 AU b) 20 AU c) 30 AU

a) 10 AU

The north celestial pole is 35 degrees above your northern horizon. This tells you that you are at a) latitude 35 degrees north. B) longitude 35 degrees East. C) Latitude 35 degrees South.

a) latitude 35 degrees north.

The balance between pressure in higher mass stars result in lower core temperature, slower fusion rates, and longer lifetimes. (T or F)

false

Today the Sun will rise and set about a) less than 10-degrees south of the E-W line b) less than 10-degrees north of the E-W line c) about 20-degrees south of the E-W line d) about 20-degrees north of the E-W line.

a) less than 10-degrees south of the E-W line

Beijing and Philadelphia have about the same latitude but different longitudes. Therefore, tonight's Sky in these two places will a) look about the same. B) have completely different sets of constellations. C) have partially different sets of constellations.

a) look about the same.

The main ingredients of most moons of the jovian planets are a) rocky ore and an outer layer of ices b) frozen hydrogen compounds c) hydrogen and helium.

a) rocky ore and an outer layer of ices

the age of our solar system is about a. 1/3 the age of the universe. b. 3/4 the age of our universe. c. 2 billion years younger than our universe.

a. 1/3 the age of the universe.

What approximate altitude is the North Star viewed from Orlando?

about 29 degrees (our latitude)

What is the celestial sphere

an imaginary sphere encompassing the earth upon which we visualize or imagine the stars attached to

The upper limit of the mass of a white dwarf star is (a) one solar mass, b) 1.4 solar masses, (c) three solar masses.

b) 1.4 solar masses

The approximate temperature required for hydrogen to fuse into helium is. A) 1,000,000 K. b) 10,000,000 K. c) 5772 K

b) 10,000,000 K.

The sunspot cycle is a) 110 years b) 11 years. C ) 6 months

b) 11 years

The week after the full moon, the moons phase is a) First quarter b) Third quarter. C) New Moon

b) Third quarter.

Jupiter is denser than Saturn because a) it has a larger proportion rock and metal content b) it has a larger proportion of hydrogen c) its greater mass and gravity compresses its interior.

c) its greater mass and gravity compresses its interior.

The largest mass of a Brown Dwarf Star is a) equal to that of the Sun b) twice that of the Sun c) less than a tenth that of the Sun d) half that of the Sun

c) less than a tenth that of the Sun

Most stars have mass a) Much greater than our Sun b) Are about the same of our Sun, c) less than half the mass of our Sun.

c) less than half the mass of our Sun.

Two stars are in the same constellation. A ) must be a part of the same star cluster in space. B) must have been discovered about the same time. c) may actually be far away from each other.

c) may actually be far away from each other.

The brightest stars in a constellation are a ). All belong to the same star cluster B ) all lie at about the same distance from Earth. c) may be quite far away from each other.

c) may be quite far away from each other.

Astronomers have determined that the universe is. a. 14 million years old. b. 10,000 years old. c. 14 billion years old. d. 140 billion years old.

c. 14 billion years old.

The nuclear fusion converts hydrogen to helium plus energy (according to Einstein's famous equation). the percent of mass converted to energy in this process is about a) 20% of the starting mass b) 10% of the starting mass c) 1.5% of the starting mass d) 0.7% of the starting mass

d) 0.7% of the starting mass

In the 1-to-10 billion scale, the sun is the size of a grapefruit, and the distance to the nearest star (Alpha Centuri, 4.5 light years away) is: a. 1 mile b. 10 miles c. 100 miles d. The distance from Washington DC to San Francisco.

d. The distance from Washington DC to San Francisco.

What are the three key components of our galaxy?

disk, center bulge, halo

What prevents the collapse of a low mass star corpse into a neutron star or black hole?

electron degeneracy pressure

t/f The earth is closer to the sun in our winter. According to Kepler's laws, the Earth is travelling slower than it is in our summer.

false

t/f With the unaided eye, we can see over one million stars in our sky

false

What is this plot?

h-r diagram

What are the primary composition of Jupiter and Saturn?

hydrogen and helium

List jovian planets in order of their distance from the Sun.

jupiter, saturn, uranus, and neptune

Which planet in our solar system has the largest magnetic field and why?

jupiter. much of its interior is metallic hydrogen, which means free electrons. it spins rapidly on its axis, including current in the metallic hydrogen which in turn produces a large magnetic field.

What are globular clusters and where are they found?

large clusters (as many as a million stars) of older stars that are located mostly in the milky way halo

How does one calculate the luminosity of a star having measured its apparent brightness and distance?

luminosity = (4pi) x (distance^2) x (apparent brightness)

What are the "Terrestrial Worlds?"

mercury, venus, earth, and mars

What limits the collapse of a neutron star?

neutron degeneracy

Mnemonic for OBAFGKM

only bad astronomers forget generally known mnemonics

What is the approximate size of a White Dwarf star?

radii are about the size of earth

Who was Vera Rubin?

she was the astronomer who first suggested that dark matter existed to explain the rotation curve of stars in our galaxy

Define speed, velocity, and acceleration. (include units)

speed = distance/time (M/S ). Velocity = speed and direction. EX. 10m/s due east acceleration = rate of change in velocity. (m/s2)

write the definition of a light year

the distance light travels in a year

What is the main characteristic of a star that defines its lifetime, temperature, and luminosity?

the star's mass

Degeneracy pressure prevents very low mass stars (less than 0.08 time the Sun's mass) from producing pressures and temperatures needed for the fusion of hydrogen into helium. (T or F)

true

Saturn contains more mass than the total of all bodies in the solar system except the Sun and Jupiter. T or F

true

Some moons of jovian planets are about the size of some terrestrial planets. T or F

true

Tatian, the largest moon of Saturn has an atmosphere of nitrogen, methane, and complex hydrocarbons. T or F

true

The Milky Way is a dynamic system of stars, continually giving birth to new stars and planetary systems. T or F

true

The Sun is made mostly of hydrogen and helium gas. T or F

true

The center of our galaxy is hidden from view in the visible spectrum range by gas and dust in the galactic plane. T or F.

true

The densities (grams per cubic centimeter) of the Terrestrial Worlds are between 4 and 5.5g/cm3. T or F

true

The sun's corona is much, much hotter than the photosphere (The surface we see in a telescope) True or false?

true

jupiter contains more mass that the total of all bodies in the solar system except the Sun. T or F

true

t/f In general, planets advance from West to East with respect to the distant stars.

true

t/f Neutron star radii are about the size of the distance from UCF to downtown Orlando.

true

t/f Occasionally, planets show retrograde motion (seems to reverse direction)

true

t/f The Milky Way, our home Galaxy, is one of billions of galaxies in the observable universe.

true

t/f The earth spins on its axis and rotates around the sun in the counterclockwise direction.

true

t/f all the elements used to makeup our bodies were produced in the big bang, 14 million years ago

true

Which of the major planets has an extreme tilt in its rotation axis?

uranus

What are the primary components of Uranus and Neptune?

various hydrogen compounds, rocks and hydrogen and helium

Which of the major planets is most like the Earth in terms of size and composition?

venus

List the Terrestrial Worlds that have an atmosphere.

venus, earth, and mars

Define the zenith, horizon, and Meridian.

zenith - point directly overhead horizon - circle 90 degrees from the the zenith meridian - circle from the north pole to the south pole